Essay on Helping Others Essay on Helping Others People are selfish by nature, however we have demonstrated times of great sacrifice when such sacrifice is needed.
The ancestry of humans reflected in the genomic signature. A phylogenetic analysis of the human genes reveals the relative percentage of the genome that arose at a series of stages in biological evolution The intertwining of animal and bacterial genomes is not Computer friend or foe essay historical: For instance, many invertebrates have intracellular bacterial symbionts whose genes encode metabolic capabilities lacking in animals, such as the synthesis of essential amino acids 24photosynthesis 25or chemosynthesis Certain marine invertebrates that feed on algae maintain algal plastids as photosynthetically active symbionts, a behavior that allows the host to use photosynthate as a food source for extended periods These metabolic add-ons allow the animal to thrive by adapting to otherwise noncompetitive lifestyles e.
Further, such phenomena fit the definition of epigenetic features. Recent studies have revealed that bacterial pathogens 29 and other environmental factors 30 can alter the activities of epigenetic machinery. It is to be anticipated that such influences will extend to all types of animal—bacterial interactions, including those described above.
Microbial communities in the vertebrate gut respond to the host diet over both daily and evolutionary time scales, endowing animals with the flexibility to digest a wide variety of biomolecules and cope with and even flourish under conditions of diet change 15 For example, the gut microbiome of most people in the United States is adapted to digest a high-fat, high-protein diet, whereas populations in rural Malawi and the Amazonas of Venezuela have distinct microbial consortia and functional gene repertoires optimized for breaking down complex carbohydrates The gut microbiome adapts to changing diets and conditions not only by shifting community membership but also by changing gene content via horizontal gene transfer.
For instance, the gut bacterium Bacteroides plebeius, found in some Japanese people, bears a Computer friend or foe essay transferred horizontally from the marine bacterium Zobellia galactanivorans, giving the gut symbiont the capacity to degrade seaweed polysaccharides More generally, human-associated bacteria have a fold higher rate of gene transfer than do bacteria in other environments, highlighting the important role of gene transfer in host-associated bacterial communities Bioinformatic analyses have revealed that interactions with animals also influence the size and content of the genomes of their bacterial partners.
Recent studies have shown that genome reduction also occurs in segmented filamentous bacteria Candidatus Savagellamembers of the mammalian microbiota that are critical for the maturation of the immune system Conversely, in Bacteroides thetaiotaomicron, another member of the mammalian intestinal microbiota, adaptation to a gut habitat rich in complex carbohydrates has driven the expansion of at least two gene families: The genomic basis for other microbial adaptations among gut microbes is less clear.
One possible selection pressure is host temperature. In aquatic environments such as the deep sea, host fishes and invertebrates conform to the temperature of the environment, so temperature-driven coevolution would be unlikely in these habitats.
In contrast, terrestrial environments often have broad, short-term daily and long-term seasonal fluctuations in temperatures. It is in these habitats that endothermy maintaining a constant body temperature by metabolic means evolved as a shared character in birds and mammals.
The reciprocal may also be true, i. Constant high temperature speeds up bacterial fermentation, providing rapid and sustained energy input for the host.
These benefits are apparent when comparing conventional to germ-free mammals, which require one-third more food to maintain the same body mass Keeping their microbes working at optimum efficiency likely offered a strongly positive selection pressure for the evolution of genes associated with the trait of endothermy in birds and mammals.
Partners in Animal Development Animal development has traditionally been viewed as an autonomous process directed by the genome. Because it both originated and evolved in a microbe-rich environment, animal development deserves a reexamination, at least in part, as an orchestration of animal-encoded ontogeny and interdomain communication 40 Although relatively few studies have been reported until recently, these early data lead us to anticipate that microbes play a role in providing signals for multiple developmental steps.
From their earliest stages of development, animals use sophisticated mechanisms to manage their microbial environment. Physical barriers, such as capsules, chorions, and mucus, protect eggs by excluding microbes, and chemical barriers, including antimicrobial peptides AMPsshape the composition of the associated microbiota Conversely, several animals recruit specific bacteria to their embryonic surfaces to provide protection against potential pathogens For example, the shrimp Palaemon macrodactylus is protected from the fungus Lagenidium callinectes by 2,3-indolinedione that is produced by an Alteromonas sp.
Although many animals, including a wide variety of insects, have transovarial i. Whereas developmentally important symbioses have been documented throughout the postembryonic larval and juvenile stages of vertebrate and arthropod life cycles, the roles of symbiotic microbes during normal embryonic development are just beginning to be studied.
Unlike vertebrates whose embryos develop inside enclosures that physically block bacterial associations, many invertebrates acquire their symbionts through the female germ line. Here, we may expect to find regulatory signals being generated by microbes and interactions between host and symbiont development It is apparent that evolution has selected for anatomical, cellular, and molecular determinants that act during this period to prepare newborn animals for interactions with the microbial world.
Ample evidence shows that microbes act directly as agents of postembryonic development. For example, fucosyltransferases decorate the surface of the embryonic mammalian intestine with fucose residues that provide a nutrient source for gut microbes, including B.
In the squid-vibrio system, a complex organ forms during embryogenesis that facilitates subsequent colonization by the symbiotic bacterium Vibrio fischeri Intriguingly, the host regulatory pathways that control immune responses to microbes appear also to have central roles in animal development, underscoring the intimate relationships between development and host—microbe interactions 58 Perhaps the most pervasive example of microbial signaling in animal development is the induction of settlement and metamorphosis of many marine invertebrate larvae Marine invertebrate metamorphoses offer valuable models for exploring the basis of bacterial signaling in animal development in a setting where the very persistence of marine ecosystems depends on it.Batman is a fictional superhero appearing in American comic books published by DC yunusemremert.com character was created by artist Bob Kane and writer Bill Finger, and first appeared in Detective Comics #27, in Originally named the "Bat-Man", the character is also referred to by such epithets as the Caped Crusader, the Dark Knight, and the World's Greatest Detective.
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