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CD4 is found on the surface of immune cells such as helper T cells, monocytes, macrophages, and dendritic cells. It was discovered in the late 1970s and was originally known as leu-3 and T4 (after the OKT4 monoclonal antibody that reacted with it) before being named CD4 in 1984. [5] In humans, the CD4 protein is encoded by the CD4 gene. [6] [7]
Perhaps the best example of the importance of CD4 + T cells is demonstrated with human immunodeficiency virus (HIV) infection. HIV mainly targets lymphoid CD4 + T cells, but can infect other cells that express CD4 such as macrophages and dendritic cells (both groups express CD4 at low levels). [citation needed]
Evolution of angiosperms shown in diagram format, per APG IV. The APG IV system of flowering plant classification is the fourth version of a modern, mostly molecular-based, system of plant taxonomy for flowering plants (angiosperms) being developed by the Angiosperm Phylogeny Group (APG).
A germination rate experiment. Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants. [1]Plant physiologists study fundamental processes of plants, such as photosynthesis, respiration, plant nutrition, plant hormone functions, tropisms, nastic movements, photoperiodism, photomorphogenesis, circadian rhythms, environmental stress physiology, seed ...
Maize (Zea mays, Poaceae) is the most widely cultivated C 4 plant.[1]In botany, C 4 carbon fixation is one of three known methods of photosynthesis used by plants. C 4 plants increase their photosynthetic efficiency by reducing or suppressing photorespiration, which mainly occurs under low atmospheric CO 2 concentration, high light, high temperature, drought, and salinity.
A floral diagram is a graphic representation of the structure of a flower. It shows the number of floral organs, their arrangement and fusion. Different parts of the flower are represented by their respective symbols. Floral diagrams are useful for flower identification or can help in understanding angiosperm evolution.
Plant hormones (or phytohormones) are signal molecules, produced within plants, that occur in extremely low concentrations. Plant hormones control all aspects of plant growth and development, including embryogenesis, [1] the regulation of organ size, pathogen defense, [2] [3] stress tolerance [4] [5] and reproductive development. [6]
The primary function of pigments in plants is photosynthesis, which uses the green pigment chlorophyll along with several red and yellow pigments that help to capture as much light energy as possible the other pigments ic carotenoids'. Pigments are also an important factor in attracting insects to flowers to encourage pollination.