Rochester Institute of Technology The development of the brain and the development of the human society occurred in relative parallel. While people were learning to live together cooperatively, they were also adapting to the new non-physical environment they found themselves in. A review of literature concerning human society and culture, as well as certain psychological adaptations is presented. The author intends to demonstrate key ways in which society influenced psychological development, and likewise ways in which the human mind steered the growth of the cultures we see in the world today.
Freeman and Gwyn A. The Plant Health Instructor. Although lacking an immune system comparable to animals, plants have developed a stunning array of structural, chemical, and protein-based defenses designed to detect invading organisms and stop them before they are able to cause extensive damage.
Humans depend almost exclusively on plants for food, and plants provide many important non-food products including wood, dyes, textiles, medicines, cosmetics, soaps, rubber, plastics, inks, and industrial chemicals.
Understanding how plants defend themselves from pathogens and herbivores is essential in order to protect our food supply and develop highly disease-resistant plant species. This article introduces the concept of plant disease and provides an overview of some defense mechanisms common among higher plants.
A close examination of plant anatomy is presented, as well as some of the ecological relationships that contribute to plant defense and disease resistance.
Special care has been taken to illustrate how products used in everyday life are derived from substances produced by plants during defense responses. Disease can be caused by living biotic agents, including fungi and bacteria, or by environmental abiotic factors such as nutrient deficiency, drought, lack of oxygen, excessive temperature, ultraviolet radiation, or pollution.
In order to protect themselves from damage, plants have developed a wide variety of constitutive and inducible defenses. Constitutive continuous defenses include many preformed barriers such as cell walls, waxy epidermal cuticles, and bark.
These substances not only protect the plant from invasion, they also give the plant strength and rigidity. In addition to preformed barriers, virtually all living plant cells have the ability to detect invading pathogens and respond with inducible defenses including the production of toxic chemicals, pathogen-degrading enzymes, and deliberate cell suicide.
Plants often wait until pathogens are detected before producing toxic chemicals or defense-related proteins because of the high energy costs and nutrient requirements associated with their production and maintenance.
In a similar way, many pathogens establish intimate connections with their hosts in order to suppress plant defenses and promote the release of nutrients. Pathogens that keep their host alive and feed on living plant tissue are called biotrophs. Examples of biotrophic pathogens include the powdery mildew fungus Blumeria graminis and the bacterial rice pathogen Xanthomonas oryzae.
Other pathogens resort to brute force like thieves who blast open a bank vault with explosives. These pathogens often produce toxins or tissue-degrading enzymes that overwhelm plant defenses and promote the quick release of nutrients. These pathogens are called necrotrophs, and examples include the gray mold fungus Botrytis cinerea and the bacterial soft-rot pathogen Erwinia carotovora.
Some pathogens are biotrophic during the early stages of infection but become necrotrophic during the latter stages of disease.
These pathogens are called hemibiotrophs and include the fungus Magnaporthe grisea, the causative agent of rice blast disease. Powdery mildew on a maple leaf Figure 2. Rice blast disease on rice leaves Figure 3. Blackleg soft-rot on a potato tuber Most biotrophic and hemibiotrophic pathogens can only cause disease on a relatively small group of host plants because of the slightly different set of specialized genes and molecular mechanisms required for each host-pathogen interaction.
The host range refers to the plant species on which a pathogen is capable of causing disease. For example, brome mosaic virus BMV infects grasses such as barley but not legumes. A plant species that does not show disease when infected with a pathogen is referred to as a non-host plant species for that pathogen.
Organisms that do not cause disease on any plant species, such as the saprophytic bacterial species Pseudomonas putida, are referred to as non-pathogens.
When a pathogen is capable of causing disease on a particular host species, two outcomes are possible: A compatible response is an interaction that results in disease, while an incompatible response is an interaction that results in little or no disease at all.
Although a particular plant species may be a susceptible host for a particular pathogen, some individuals may harbor genes that help recognize the presence of the pathogen and activate defenses. For example, some tomato cultivars show disease when infected with the bacterial pathogen Pseudomonas syringae a compatible responsebut others cultivar Rio Grande, for example are capable of recognizing the bacteria and limiting disease via resistance an incompatible response.
Disease resistance exists as a continuum of responses ranging from immunity the complete lack of any disease symptoms to highly resistant some disease symptoms to highly susceptible significant disease symptoms. Tomato leaves exposed to the bacterial pathogen P.
The leaf on the left is diseased, and the leaf on the right is resistant. Surveillance and Detection of Microbial Pathogens Figure 5. Bacterial flagella are often recognized by plants during basal resistance.
Plants have developed multiple layers of sophisticated surveillance mechanisms that recognize potentially dangerous pathogens and rapidly respond before those organisms have a chance to cause serious damage.
These surveillance systems are linked to specific pre-programmed defense responses. Basal resistance, also called innate immunity, is the first line of pre-formed and inducible defenses that protect plants against entire groups of pathogens.
Basal resistance can be triggered when plant cells recognize microbe-associated molecular patterns MAMPs including specific proteins, lipopolysaccharides, and cell wall components commonly found in microbes.
The result is that living plant cells become fortified against attack. Non-pathogens as well as pathogens are capable of triggering basal resistance in plants due to the widespread presence of these molecular components in their cells.
|Subclasses of Mammals||The Functionality and Evolution of Aposematic Coloration Thomas Sterling In the realm of predator and prey, the preys are at a continual disadvantage, where they must always be on alert, in preparation for an attack. In many cases, natural selection has aided in alleviating this necessity for persistent alertness with mechanisms that provide for various degrees of defense.|
|The Emergence of Society and Culture||No one quite knows how the sleek feline made its way to American shores during the late 19th century. However, thanks to its sociable nature, lithe body, and dark-tipped creamy coat, the Siamese became one of the country's most beloved cat breeds.|
|The Polyvagal Theory||The process of coevolution describes interactions involving reciprocal evolutionary adaptations in two species, in which a change in one species acts as a selective force on another species, and counteradaptation by the second species, in turn, is a selective force on individuals in the first species Rausher|
|THE EVOLUTION OF MAMMALS||Precursors can be found in Freud's earlier publications:|
|Cite This Essay:||Functional and histological studies of the vagus nerve and its branches to the heart, lungs and abdominal viscera in the cat. Journal of Physiology - London,|
Pathogens have developed countermeasures that are able to suppress basal resistance in certain plant species.The Evolution of Ichthyosaurs- Large Aquatic Reptiles Essay - The Evolution of Ichthyosaurs- Large Aquatic Reptiles In the early ’s, a new discovery that left paleontologists in awe was the fossil finding of the immeasurable amount of species of reptiles, Ichthyosaurs.
Start studying Mechanisms of Evolution I. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Greene HW () Antipredator mechanisms in reptiles. In: Gans C, Huey RB (eds) Biology of the Reptilia, vol Alan R.
Liss, New York, pp 1– Google Scholar. The Evolution of Reptiles Words Feb 18th, 5 Pages The first fossilized amniotes discovered were dated to the early Pennsylvanian sub-period of the Carboniferous period, about to million years ago, in the stumps of the oldest extant vascular plant division, the lycopods, in Nova Scotia.
Evolution of Human Mate Choice David C. Geary, Jacob Vigil, and Jennifer Byrd-Craven University of Missouri – Columbia mechanisms that operate within species and are principle reptile, and mammal (Andersson, ; Sargent, Rush, Wisenden, & Yan, ).
One result of female choice is the evolution of exaggerated male traits. An example. A molecular mechanism for the origin of a key evolutionary innovation, the bird beak and palate, revealed by an integrative approach to major transitions in vertebrate history Search for more papers by this author.
Zachary S. Morris. The skull roof tracks the brain during the evolution and development of reptiles including birds, Nature.