GA3 Producing Fusarium and its Impact on Growth

GA3 Producing Fusarium and its Impact on Growth Isolation and characterization of Gibberellic acid 3 producing Fusarium sp. from Belgaum agriculture land and its impact on green pea and rice growth promotion Abstract Worldwide ultimate aim of any agriculture sector or farmer is to take maximum yield. Sufficient supply of nutrients and fertilizer are not able to give maximum yield. There are numerous factors which are responsible for low yield, among that one is the environment stress or the unstable climate conditions. To increase the yield there are numerous approaches like use of genetically modified crops, but in India it is controversial approach and another approach is the use of multifunctional plant hormone like Gibberellic acid 3 (GA3). This research mainly involves the production of GA3 from fungal species and to apply it on crop plants. Fusarium species were isolated from Belgaum agriculture soil and screened for GA3 production under submerged fermentation. Strain showing maximum GA3 yield (strain M104) was taken to study the effect of various parameters on GA3 production, like incubation time (1 – 12 days), initial pH (5.0 -8.0), incubation temperature (20 – 40  °C), pH (5.0 -8.0), and carbon and nitrogen sources. The maximum production of GA3 was observed on day 8 at 30  °C, and pH 5.5 with glucose and ammonium chloride as good carbon and nitrogen sources, respectively. After optimization, a 6.56-increase in GA3 production was observed. The GA3 production was confirmed by thin layer chromatography. The GA3 crude extract obtained using submerged fermentation was then used to study its effect on germination and growth of green pea plant and paddy crops. It was observed that GA3 treated crops showed uniform growth and they were taller than non-treated plants, suggesting its application in increasing the crop plant harvests. Key words: Fusarium sp, isolation, gibberellic acid, optimization, submerged fermentation, crop plants. Introduction Gibberellic acids, also known as gibberellins, are the complex organic molecules acting as plant growth hormones. They are chemically known as diterpenoid acids having molecular formula C19H22O6. They regulate the functions like cell division, cell elongation, sex expression, seed germination, breakdown of seed dormancy and flowering etc. In microorganisms such as bacteria and fungi, gibberellic acid 3 is the principal product of gibberellins, act as secondary metabolite (Bruckner and Blecschmidt, 1991; Karakoc and Aksoz, 2006). Till now, 136 gibberellins were isolated from various plants, and among that gibberellic acid 3 shows maximum biological activity (Rodrigues et al., 2011). The use of GA3 has been approved by food and drug administration (FDA) because of its tremendous application and nontoxic properties, and its safety for environment and human was confirmed by Material Safety Data Sheet (MSDS) (Rodrigues et al., 2011). In counties under development where mainly the economy relies on agriculture, the farmers have to use fertilizers and plant hormones to increase production. As most of fertilizers are associated with environmental pollution, plant growth hormones like gibberellic acid 3 have to be produced cost-effectively in huge amounts in order to enhance the quantity of agricultural products (Bilkay et al., 2010). Three routes to obtain GA3 have been reported, viz. extraction from plants, chemical synthesis and microbial fermentation. Among this the third method is the most common method to produce GA3 (Rios-Iribe et al., 2011). GA3 is industrially produced by Gibberella fujikuroi / Fusarium moniliforme under submerged (Santos et al., 2003; Karakoc and Aksoz, 2006). It is also produced by several other fungal species such as Aspergillus niger and Fusarium species and some bacteria such as Pseudomonas, Rhizobium, Azobactor, and Azospirillu species (Rademacher, 1994). All above species produced ver y low yield of GA3 except Fusarium species in which most of the strains show the highest yield of GA3 than any other microbes (Rangaswamy, 2012). The search for new fungal species like Fusarium species capable of producing an important amount of GA3 is a continuous exercise. The aim of the present study was therefore to isolate and characterize a GA3 producing Fusarium sp. from soil, optimize the culture conditions for maximum GA3 production, and to evaluate its effect on green pea and rice growth promotion. Materials and Methods Soil sample selection To isolate strains of Fusarium, the soil sample was taken from Belgaum agriculture area (Karnataka state, India). This soil was black coloured having high water holding capacity, good fertility and also best soil for crops like paddy, all types of beans, sugarcane and all types of vegetables. Isolation of Fusarium species The soil sample collected from Belgaum agriculture land was taken, serially diluted in distilled water and inoculated in a Malachite green agar (MGA). Petri plates containing 15 g of peptone, 0.01 g of Malachite Green (triaryl methane dye), 1 g of potassium dihydrogen phosphate, 0.5 g of magnesium sulphate, and 20 g of agar per 1000 ml of distilled water were prepared. The incubation was carried out at 30  °C for 5 days (Castellà ¡ et al., 1977). The resulted various colonies were picked up and further inoculated in a potato dextrose agar (PDA) plate and incubated for a week for secondary pigmentation. The colony with different morphology and colour pigmentation were sub cultured on PDA slants and labelled (Avinash et al., 2003). The lactophenol cotton blue technique was used to study the characteristics of the fungal isolate (William and Cross, 1971). Screening of the isolates for GA3 production under submerged fermentation The Czapack Dox media (CD broth) containing sucrose (30 g), sodium nitrate (3 g), dipotassium hydrogen phosphate (1 g), potassium dihydrogen phosphate (0.5 g), magnesium sulphate (0.5 g), potassium chloride (0.5 g) and ferrous sulphate (0.1 g) per 1000 ml of distilled water was used. The CD broth was prepared in conical flask and adjusted the pH to 7.0, and sterilised in an autoclave for 20 min at 15 psi. After cooling the medium, it was aseptically inoculated (1 Ãâ€" 108 spores / ml) with individual isolated strains. The fermentation flasks were kept on a rotary shaker (100 rpm) at 30  °C for 12 days (Kahlon et al., 1986; Karakoc et al., 2006; Rangaswamy, 2012). GA3 pre-treatment, extraction and estimation The fermented broth was taken and centrifuged at 13200 rpm for 10 min and the supernatant was taken and acidified to pH 2-2.5 using 1N HCl. GA3 was extracted trice using equal amount of ethyl acetate/NaHCO3 (Cho et al., 1979). The ethyl extract was kept on hot air oven at 50  °C overnight to remove ethyl acetate and obtain crystals of GA3 (Kahlon et al., 1986; Karakoc and Aksoz, 2006; Karakoc et al., 2006; Bilkay et al., 2010; Rangaswamy, 2012). It was estimated by Berrios et al. (2004) spectrophotometric method and absorption was read at 254 nm in UV-VIS spectrophotometer (Elico, SL-159 model, India). Confirmation of GA3 by thin layer chromatography (TLC) The slurry of silica gel was poured on a TLC plates, air dried, and the matrix was activated by keeping the plates on hot air oven at 80  °C for 1 h. GA3 dissolved in ethanol was added as a spot and plates were run using mobile phase containing isopropanol : ammonia : water (10:1:1) for 2 h. The plates were removed, sprayed with 3% sulphuric acid containing 50 mg FeCl3 and heated in oven at 80  °C for 10 min. The GA3 appeared as greenish black/spot fluorescence under UV light (Cavell et al., 1967; Srivastava et al., 2003). Optimization of culture conditions for maximum GA3 production by Fusarium sp. (isolate M-104). The incubation time for GA3 production by the fungal isolate under submerged fermentation at 30  °C and at initial pH 7.0 was analysed by inoculating CD broth with 1 ml of fungal spores and incubating on a rotary shaker (100 rpm) for 12 days. The sample was taken every day as the fermentation proceeds in order to find the most suitable incubation time for GA3 production. The effect of pH on GA3 production was studied by adjusting CD broth at different pH, viz. 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, and 8.0. The cultivation flasks were inoculated with 1.5% (v/v) inoculum, and incubated for 8 days on rotary shaker (100 rpm) at 30  °C. The effect of temperature on GA3 production was investigated by inoculating the fungal spores in CD broth of pH 7.0 and by incubating at three different temperatures 20, 30, 40, and 50  °C with other conditions remained same. The effect of carbon sources on GA3 secretion was analysed by replacing the sucrose in the CD broth of pH 5.5 by dextrose, glucose, ma nnitol, and starch, and by incubating at 30  °C for 8 days. The effect of nitrogen sources on GA3 secretion was analysed by replacing the sodium nitrate in the CD broth of pH 5.5 by glycine, ammonium chloride and ammonium sulfate at 30  °C for 8 days. Effect of GA3 on pea plant and paddy crops Seeds of pea plants were soaked in 200 ppm of GA3 fermented filtrate for 12 h and then sown in autoclaved soil. After a period of 8 days, 100 ppm of GA3 was sprayed on the plant for each alternative day for another 8 days. The control was soaked in water and sown in autoclaved soil and sprayed with distilled water only. The growth of both the control and test pea plants was monitored over a period of 15 days. 10 paddy seeds were soaked in 300 ppm of GA3 solution for about 2 days and sown in soil. They were sprayed with 200 ppm of GA3 after growth. The control seeds were soaked in water for the same period and sprayed with only water. The observation was carried out for 25 days (Tiwari et al., 2011; Susilawati et al., 2014). Statistical analysis The experiments were carried out in triplicate. ANOVA and DMRT at 5% significance level were used to give the differences between mean values, using SPSS statistical software. Results and Discussion Isolation of Fusarium species Four strains of Fusarium species were isolated from agriculture soil sample and labelled as M101, M102, M104 and M110. The present labelling was based on following pigmentation black, grey, blue and red, respectively. All strains had cottony growth appearance which is one of the important morphological characteristic of the Fusarium species. By staining the fungi with lactophenol cotton blue dye, it was observed that they had non septate hyaline mycelium/ hyphae as shown in figure 1a. The macrospores of banana shape were reseptated which is a unique microscopic feature of Fusarium species as shown in the figure1b. The isolation medium containing malachite green was chosen since malachite green inhibits the radial colony growth of the saprophytes and allows only growth of Fusarium species (Castellà ¡ et al., 1997). Screening for isolates for GA3 production GA3 can be commercially produced by submerged fermentation using different media but the most common synthetic medium is the Czapack Dox medium (CD broth) (Rangaswamy, 2012). The isolated strains M101, M102, M104 and M110 were subjected to submerged fermentation to check their ability for GA3 production. The different amounts of GA3 produced are given in the table 1 and Figure 2, and the strain M104 was the highest producer of GA3 among the four isolates. Similarly, Aspergillus niger strains produced different amounts of GA3 with the highest of 150.35 mg/l for A. niger Fursan (Cihangir and Aksoz, 1993). Likewise, various amounts of GA3 were produced by Lentinus tigrinus and Laetiporus (Ozcan, 2001). Optimization of culture conditions for maximum GA3 production by Fusarium isolate M104 The optimization of cultural parameters like incubation time, temperature, and pH, and nutritional conditions like nitrogen and carbon sources, is necessary to produce GA3 in a significant amount. Time course for GA3 production by the isolate M104 was studied. GA3 production started on day 3 and maximum production was observed at day 8, although statistically at par with day 9 and 10 (Table 2). Similar incubation time was noted for GA3 production by Fusarium monilifome (Rangaswamy, 2012). 9 days was optimal time for GA3 secretion by Fusarium fujikuroi SG2 (Uthandi et al., 2010) and Fusarium monilifome (Kobomoje et al., 2013). In contrast, a higher incubation time of 12 days was observed by for Fusarium moniliforme(Kahlon and Malhotra, 1986) and Aspergillus niger (Bilkay et al., 2010). The optimum incubation time for GA3 production by various fungal species depend therefore on the strain used. The short incubation period observed for GA3 production by fungal isolate M104 makes the fer mentation cost-effective. Among all pH investigated, the pH 5.5 showed the maximum production of GA3 which was 1478.2 mg/L (Table 2). pH 5.5 was also optimum for GA3 production by Fusarium monilifome (Kahlon and Malhotra, 1986; Kobomoje et al., 2013) and Fusarium fujikuroi SG2 (Uthandi et al., 2010). Bilkay et al. (2010) reported pH 5.0 as optimal time for GA3 production by Aspergillus niger, whereas pH 7.0 was optimum for GA3 production by Fusarium monilifome (Rangaswamy, 2012). The effect of temperature on GA3 production was analysed, and maximum production was observed at 30  °C (Table 3). The production of GA3 by various fungal species was also seen at an optimum temperature of 30  °C (Bilkay et al., 2010, Uthandi et al., 2010; Rangaswamy, 2012; Kobomoje et al., 2013). 25  °C was also optimum for GA3 production by Gibberella fujikuroi (Gelmi et al., 2002). A low GA3 yield at higher temperature was also recorded for GA3 production by Aspergillus niger (Bilkay et al., 2010). A low GA3 production was observed at higher temperatures because metabolic activities get stopped due to enzyme denaturation. The decrease in GA3 secretion by microbial species was ascribed to the variation in enzyme activity or thermal denaturation (Karakoc and Aksoz, 2006). The effect of carbon sources on GA3 production was investigated. Maximum GA3 production was seen when glucose was used as carbon source (Table 2). Similarly, glucose was best carbon source for GA3 production by Fusarium moniliforme (Rangaswamy, 2012; Kobomoje et al., 2013). However, a mixture of glucose and rice flour was necessary to get GA3 production by Fusarium fujikuroi SG2 (Uthandi et al., 2010). When the concentration of glucose was increased, a decrease in enzyme production is observed due to catabolite repression (Tudzynski, 1999). After analysing the effect of nitrogen sources on GA3 production, a significant yield was observed with ammonium chloride (Table 2). Similarly, an important yield was seen when ammonium chloride was used as nitrogen source for GA3 production by Fusarium fujikuroi SG2 (Uthandi et al., 2010). A low amount was seen when glycine was used as nitrogen source (Table 2). This can be attributed to the fact that glycine is a slowly consumed organic nitrogen source (Rodrigues et al., 2011). After exhaustion of nitrogen source, GA3 secretion starts and an important amount of carbon source is consumed (Tudzynski, 1999; Rodrigues et al., 2011). The submerged fermentation for GA3 production by the isolate M104 was carried out under shaking conditions (100 rpm) to allow proper mixing of nutrients, favouring oxygen circulation and GA3 production. A 3-fold increase was recorded for GA3 production by Aspergillus niger when the culture flasks were agitated (Bilkay et al., 2010). Rodrigues et al. (2011) reported that GA3 production has to be carried with aeration since GA3 biosynthesis requires various oxidative steps catalysed by different oxygenases. After optimization, a 6.56-enhancement in GA3 secretion was observed Thin layer chromatography (TLC) After GA3 extraction, crystals of GA3 were obtained as shown on the figure 3. After carrying TLC, the value of resolution factor (Rf) of GA3 was calculated as follow: Rf = distance from origin to solvent peak / distance from origin to sample spot detected = 7.9 cm / 10.8 cm = 0.7315 (Figure 4). The value was closing approximate to the GA3 standard value. Similarly, an approximate Rf value was recorded for the GA3 extracted from Fusarium monilifome (Rangaswamy, 2012). The TLC was also used to confirm the GA3 produced by Fusarium solani (Bhalla et al., 2010). Effect of GA3 on pea plants It is was observed that the pea plants sprayed with GA3 was 7 cm taller than the pea plants without the GA3 within a period of two weeks (Fig. 5). Similarly, size of the lily plants was increased following exogenous GA3 treatment and this was attributable to the protein synthesis stimulation (Mahmoody and Noori, 2014). Likewise, the hybridized rice plant height was increased after GA3 extract application (Srivastava et al., 2003). Effect of GA3 on paddy crops All the 10 paddy seeds treated with GA3 were able to germinate and have uniform growth, colour and height and average height was 9.5 cm within a total period of 25 days. The untreated seeds were able to germinate and had unequal growth and average height was 8.5 cm (Fig. 7). Similarly, the shoot and root heights, and the yield of chana and wheat crops were increased after GA3 extract application (Pandya and Desai, 2014). After GA3 application, an important productivity was seen for hybrid rice plant, following a better plant growth and physiological properties (Susilawati et al., 2014). The GA3 application also led to a significant yield for faba bean, compared to Ca2+ ion, and this was attributed to the improvement of growth and photosynthetic activity by the plant hormone (Al-Whaibi et al., 2010). Figure 7: Effect of GA3 on paddy crops: Uniform growth (left) and non-uniform growth (right). Paddy seeds were soaked in 300 ppm of GA3 solution for about 2 days and sown in soil. They were sprayed with 200 ppm of GA3 after growth. The control seeds were soaked in water for the same period and sprayed with only water. The observation was carried out for 25 days Conclusion Four strains of Fusarium were screened from Belgaum agriculture land by using a selective medium malachite green agar. They were confirmed as belonging to Fusarium species by lactophenol cotton blue spore staining method. The GA3 production depends on nutritional and physicochemical conditions. Strain M104 showed the highest GA3 production in CD broth. After optimization, a 5.56-increase in GA3 production was achieved. The pea plant sprayed with GA3 fungal extract was taller than unsprayed one. The effect of GA3 on paddy seeds showed uniform and more growth than control (without GA3). The isolate M104 can thus be used as a potent fungal species for GA3 production.   

The Hunters: Moonsong Chapter Twenty-Five

Dear Diary, I can't believe what a fool I am, what a faithless, worthless fool. I should never have kissed Damon, or let him kiss me. The look on Stefan's face when he found us was heartbreaking. His features were so stiff and pale, as if he was made of ice, and his eyes were shining with tears. And then it seemed like a light went out inside him, and he looked at me like he hated me. Like I was Katherine. No matter what happened between us, Stefan never looked at me like that before. I won't believe it. Stefan could never hate me. Every beat of my heart tells me that we belong together, that nothing can tear us apart. I've been such a fool, and I've hurt Stefan, although that was the one thing I never wanted to do. But this isn't the end for us. Once I apologize and explain what a moment of madness he witnessed, he'll forgive me. Once I can touch him again, he'll see how sorry I am. It was only the adrenaline from coming so close to death, from that car chasing after us. Neither Damon nor I really wanted the other one, that kiss was just us clinging hard to life. No. I can't lie. Not here. I have to be honest with myself, even if I pretend with everyone else. I wanted to kiss Damon. I wanted to touch Damon. I always have. But I don't have to. I can stop myself, and I will. I don't want to cause Stefan any more pain. Stefan will understand that, will understand that I'll do anything I can to make him happy again, and then he'll forgive me. This can't be the end. I won't let it be. Elena closed her journal and dialed Stefan's number once more, letting the phone ring until it went to voicemail and then hanging up. She'd cal ed him several times last night, then over and over again this morning. Stefan could see her cal ing, she knew. He always kept his phone on. He always answered, too; he seemed to feel some obligation to be available since he had the phone with him. The fact that he wasn't answering meant he was avoiding her on purpose. Elena shook her head fiercely and dialed again. Stefan was going to listen to her. She wasn't going to let him turn her away. Once she explained and he forgave her, everything could go back to normal. They could end this separation that was making them both so unhappy – clearly, it hadn't worked out the way she intended. Except, what exactly was she going to say? Elena sighed and flopped down backward onto her bed, her heart sinking. Adrenaline from the car's pursuit aside, al she could real y say was that she hadn't meant for the kiss with Damon to happen, that she didn't want him, not real y. She wanted Stefan. Al she could tel him was that it wasn't something she had expected or planned. That Damon wasn't the one she wanted. Not truly. That she would always choose Stefan. That would have to be enough. Elena dialed again. This time, Stefan picked up. â€Å"Elena,† he said flatly. â€Å"Stefan, please listen to me,† Elena said in a rush. â€Å"I'm so sorry. I never – † â€Å"I don't want to talk about this,† Stefan said, cutting her off. â€Å"Please stop cal ing me.† â€Å"But, please, Stefan – â€Å" â€Å"I love you, but†¦Ã¢â‚¬  Stefan's voice was soft but cold. â€Å"I don't think we can be together. Not if I can't trust you.† The line went dead. Elena pul ed the phone away from her ear and stared at it for a moment, puzzled, before she realized what had happened. Stefan, dear, darling Stefan who had always been there for her, who loved her no matter what she did, had hung up on her. Meredith pul ed one foot up behind her back, held it in both hands, breathed deep, and slowly pul ed the foot higher, stretching her quadriceps muscle. It felt good to stretch, to get a little blood flowing after her late night. She was looking forward to sparring with Samantha. There was a new move Meredith had figured out, a little something kickboxing inspired, that she thought Sam was going to love, once she got over the shock of being knocked down by Meredith once again. Samantha had been getting faster and more sure of herself as they kept working out together, and Meredith definitely wanted to keep her on her toes. That was, it would be terrific to spar with Samantha, if Samantha ever actual y arrived. Meredith glanced at her watch. Sam was almost twenty minutes late. Of course, they'd been out late the night before. But stil , it wasn't like Samantha not to show up when she said she was going to. Meredith turned on her phone to see if she had a message, then cal ed Samantha. No answer. Meredith left a quick voicemail, then hung up and went back to stretching, trying to ignore the faint quiver of unease running through her. She circled her shoulders, stretched her arms behind her back. Maybe Samantha just forgot and had her phone turned off. Maybe she overslept. Samantha was a hunter; she wasn't in danger from whoever – or whatever – was stalking the campus. Sighing, Meredith gave up on her workout routine. She wasn't going to be able to focus until she checked on Samantha, even though the other girl was probably fine. Undoubtedly fine. Scooping up her backpack, she headed for the door. She could get in a run on the way over. The sun was shining, the air was crisp, and Meredith's feet pounded the paths in a regular rhythm as she wove between people wandering around campus. By the time she reached Samantha's dorm, she was thinking that maybe Sam would want to go for a nice long run with her instead of sparring today. She tapped on Samantha's door, cal ing, â€Å"Rise and shine, sleepyhead!† The door, not latched, drifted open a little. â€Å"Samantha?† Meredith said, pushing it open farther. The smel hit her first. Like rust and salt, with an underlying odor of decay, it was so strong Meredith staggered backward, clapping a hand over her nose and mouth. Despite the smel , Meredith couldn't at first understand what was al over the wal s. Paint? she wondered, her brain feeling sluggish and slow. Why would Samantha be painting? It was so red. She walked through the door slowly, although something in her was starting to scream. No, no, get away. Blood. Bloodbloodbloodblood. Meredith wasn't feeling slow and sluggish anymore: her heart was pounding, her head was spinning, her breath was coming hard and fast. There was death in this room. She had to see. She had to see Samantha. Despite every nerve in her body urging her to run, to fight, Meredith kept moving forward. Samantha lay on her back, the bed beneath her soaked red with blood. She looked like she had been ripped apart. Her open eyes stared blankly at the ceiling, unblinking. She was dead.

The Metamorphosis By Franz Kafka - 1435 Words

In Franz Kafka’s The Metamorphosis, readers are thrown into a fictional setting in which the main character; Gregor Samsa, transforms into a cockroach. As a response to Gregor’s metamorphosis, his mother and his sister patiently attempt to take care of him and make him as comfortable as they can. However, Gregor’s father’s love is challenged by Gregor’s drastic change in appearance and becomes less patient, acting in complete hatred towards his son. The Metamorphosis is both a cruel and tragic story because of the multiple scenes that portrayed a failing relationship between Gregor and his family. In the following essay, I will explain three scenes in particular that proves why I believe this story is tragic. The first scene that was specifically tragic was when Gregor was describing his feelings about his job as a traveling salesman. Gregor only worked the job he despised to pay off his family’s debt to his manager, â€Å"If I didn’t hold back for my parents’ sake, I would have quit long ago†¦Ã¢â‚¬  (Kafka 4). He disliked traveling to so many places, eating meals at strange hours, the struggles he encountered with intimate relationships, and waking up early in the morning to avoid missing his train. Gregor was hardly recognized by his family for supporting them financially – after the failure of his father’s business – until he was incapable of contributing his paycheck to the family. He was expected to bring his earnings home without any consideration of spending it on anything heShow MoreRelatedThe Metamorphosis by Franz Kafka1052 Words   |  4 PagesFranz Kafka wrote one of his most popular books, The Metamorphosis, during the literary period and movement of existentialism. His novella stresses many existential ideals. 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In the novella â€Å"The metamorphosis†, â€Å"Kafka’s personal history† has been â€Å"artfully [expressed]† (Classon 82). The novella was written in 1916, before the World War 1 in German {Research}. When the novella was writte n, in the EuropeRead MoreThe Metamorphosis By Franz Kafka1380 Words   |  6 Pagesâ€Å"I cannot make anyone understand what is happening inside me. I cannot even explain it to myself†: A Psychoanalysis reading of â€Å"The Metamorphosis† by Kafka The Metamorphosis is known to be one of Franz Kafka’s best works of literature. It demonstrates the interconnection between his personal life and the protagonist, Gregor Samsa, of â€Å"The Metamorphosis.† Franz Kafka was born in 1883 and grew up in a financially stable Jewish family in Prague. 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When Gregor gets up in the morning to get ready for work and finds that he has been transformed into a cockroach, he ponders about how maybe he should just go in to work late and get fired, but then realizes that he cannot because â€Å"if [he] were not holdingRead MoreThe Metamorphosis By Franz Kafka947 Words   |  4 PagesThe Metamorphosis is a novella written by German author Franz Kafka which was first published in 1915. The novella tells the story of Gregor Samsa, a traveling salesman who one day awoke to discover he had transformed into an insect like monstrosity. Throughout the story, Gregor struggles with the horrible prospect of coming to terms with his situation, as well as copin g with the effects of his transformation, such as the fact that his family is repelled by his new form, and that he is no longerRead MoreThe Metamorphosis by Franz Kafka1021 Words   |  4 PagesFranz Kafka’s, The Metamorphosis, is a novella about Gregor Samsa, a man who devotes everything to fulfilling the needs of his family. Kafka’s existentialist perspective on the meaning of life is illustrated through the use of the protagonist of Gregor Samsa. Existentialism is a philosophy â€Å"concerned with finding self and the meaning of life through free will, choice, and personal responsibility† (Existentialism). Gregor is unable to fulfill the existentialist view of finding meaning in one’s life;Read MoreThe Metamorphosis By Franz Kafka1050 Words   |  5 PagesOn the surface, â€Å"The Metamorphosis† by Franz Kafka is an evocative story of a man transformed into a â€Å"monstrous vermin†. It seems to focus on the dark transformation of the story’s protagonist, Gregor, but there is an equal and opposing transformation that happens within Gregor’s family. Although Gregor has physically changed at the beginning of the story, he remains relatively unchanged as the novella progresses. The family, on the other hand, is forced to drastically change how they support themselves

Why Did Crocodiles Survive the K/T Extinction

You already know the story: at the end of the Cretaceous period, 65 million years ago, a comet or meteor struck the Yucatan peninsula in Mexico, triggering extreme changes in the global climate that resulted in what we call the  K/T Extinction. Within a short period of time—estimates range from a few hundred to a few thousand years—every last dinosaur, pterosaur, and marine reptile had disappeared off the face of the earth, but crocodiles, oddly enough, survived into the ensuing Cenozoic Era. Why should this be surprising? Well, the fact is that dinosaurs, pterosaurs, and crocodiles are all descended from archosaurs, the ruling lizards of the late Permian and early Triassic periods. Its easy to understand why the earliest mammals survived the Yucatan impact; they were small, tree-dwelling creatures that didnt require much in the way of food and were insulated by their fur against plunging temperatures. The same goes for birds (only substitute feathers for fur). But some Cretaceous crocodiles, like Deinosuchus, grew to respectable, even dinosaur-like sizes, and their lifestyles werent all that different from those of their dinosaur, pterosaur or marine reptile cousins. So how did crocodiles manage to survive into the Cenozoic Era? Theory #1: Crocodiles Were Exceptionally Well-Adapted Whereas dinosaurs came in all shapes and sizes—huge, elephant-legged sauropods, tiny, feathered dino-birds, towering, ravenous tyrannosaurs—crocodiles have stuck with pretty much the same body plan for the last 200 million years (with the exception of the very first Triassic crocodiles, like Erpotosuchus, which were bipedal and lived exclusively on land). Perhaps the stubby legs and low-slung posture of crocodiles allowed them to literally keep their heads down during the K/T upheaval, thrive in a wide variety of climatic conditions,  and avoid the fate of their dinosaur pals. Theory #2: Crocodiles Lived Near the Water As stated above, the K/T Extinction wiped out land-dwelling dinosaurs and pterosaurs, as well as sea-dwelling mosasaurs (the sleek, vicious marine reptiles that populated the worlds oceans toward the end of the Cretaceous period). Crocodiles, by contrast, pursued a more amphibious lifestyle, perched halfway between dry land and long, winding freshwater rivers and saltwater estuaries. For whatever reason, the Yucatan meteor impact had less of an impact on freshwater rivers and lakes than it did on saltwater oceans, thus sparing the crocodile lineage. Theory #3: Crocodiles Are Cold-Blooded Most paleontologists believe that theropod dinosaurs were warm-blooded and thus had to constantly eat to fuel their metabolisms—while the sheer mass of sauropods and hadrosaurs made them slow to both absorb and radiate heat, and thus able to maintain a steady temperature. Neither of these adaptations would have been very effective in the cold, dark conditions immediately following the Yucatan meteor impact. Crocodiles, by contrast, possess classically reptilian cold-blooded metabolisms, meaning they dont have to eat very much and can survive for extended periods in severe darkness and cold. Theory #4: Crocodiles Grew More Slowly Than Dinosaurs This is closely related to theory #3, above. Theres an increasing amount of evidence that dinosaurs of all types (including theropods, sauropods, and hadrosaurs) experienced a quick growth spurt early in their life cycles, an adaptation that better enabled them to avoid predation. Crocodiles, by contrast, grow steadily and slowly throughout their lives and would have better been able to adapt to the sudden scarcity of food after the K/T impact. (Imagine a teenaged Tyrannosaurus Rex experiencing a growth spurt suddenly needing to eat five times as much meat as before, and not being able to find it!) Theory #5: Crocodiles Were Smarter Than Dinosaurs This is probably the most controversial hypothesis on this list. Some people who work with crocodiles swear that theyre almost as smart as cats or dogs; not only can they recognize their owners and trainers, but they can also learn a limited array of tricks (like not biting their human trainer in half). Crocodiles and alligators are also fairly easy to tame, which may have allowed them to adapt more readily to the harsh conditions after the K/T impact. The problem with this theory is that some end-Cretaceous dinosaurs (like Velociraptor) were also fairly smart, and look what happened to them! Even today, when numerous mammal, reptile, and bird species have gone extinct or are seriously endangered, alligators and crocodiles around the world continue to thrive (except for those targeted by shoe-leather makers). Who knows—if things keep on going the way they have been, the dominant forms of life a thousand years from now may be cockroaches and caimans!