In addition to growth by cell division, a plant may grow through cell elongation.
This occurs when individual cells or groups of cells grow longer. Not all plant cells will grow to the same length. When cells on one side of a stem grow longer and faster than cells on the other side, the stem will bend to the side of the slower growing cells as a result.
This directional growth can occur via a plant's response to a particular stimulus, such as light phototropism , gravity gravitropism , water, hydrotropism , and physical contact thigmotropism. Plant growth and development are mediated by specific plant hormones and plant growth regulators PGRs Ross et al. Plants exhibit natural variation in their form and structure. While all organisms vary from individual to individual, plants exhibit an additional type of variation. Within a single individual, parts are repeated which may differ in form and structure from other similar parts.
This variation is most easily seen in the leaves of a plant, though other organs such as stems and flowers may show similar variation. There are three primary causes of this variation: Transcription factors and transcriptional regulatory networks play key roles in plant morphogenesis and their evolution.
During plant landing, many novel transcription factor families emerged and are preferentially wired into the networks of multicellular development, reproduction, and organ development, contributing to more complex morphogenesis of land plants. Much of developmental biology research in recent decades has focused on the use of a small number of model organisms. It has turned out that there is much conservation of developmental mechanisms across the animal kingdom. In early development different vertebrate species all use essentially the same inductive signals and the same genes encoding regional identity.
Even invertebrates use a similar repertoire of signals and genes although the body parts formed are significantly different. Model organisms each have some particular experimental advantages which have enabled them to become popular among researchers. In one sense they are "models" for the whole animal kingdom, and in another sense they are "models" for human development, which is difficult to study directly for both ethical and practical reasons.
Model organisms have been most useful for elucidating the broad nature of developmental mechanisms. The more detail is sought, the more they differ from each other and from humans. Also popular for some purposes have been sea urchins  and ascidians. From Wikipedia, the free encyclopedia.
Purchase Current Topics in Developmental Biology, Volume 50 - 1st Edition. Print Book & E-Book. ISBN , The series is approaching its 50th anniversary in , making it the longest running forum for contemporary issues in developmental biology. Each volume of .
For the journal, see Developmental Biology journal. Blastocyst Body plan Cell signaling Cell signaling networks Embryology Enhancer Fish development Gene regulatory network Ontogeny Plant evolutionary developmental biology Promoter biology Signal transduction Teratology. Archived PDF from the original on Academic Press, Burlington MA. Towards a cellular and molecular framework for Hydra regeneration".
Annual Review of Cell and Developmental Biology. Cellular and Molecular Life Sciences. Wiley Interdisciplinary Reviews-Developmental Biology. Trends in Biochemical Sciences. From Generation to Interpretation". How metazoans reach their full size: Control of Cell Size, ed. In Bate and Martinez-Arias eds. The plant's fountain of youth". Plant Growth and Development , page The secondary phloem of trees". Growth regulators and conifers: Molecular Biology and Evolution.
Archived from the original on Explicit use of et al. A Laboratory Manual, Fourth Edition. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press. Current Opinion in Cell Biology. Human embryogenesis in the first three weeks. Surface ectoderm Neuroectoderm Somatopleuric mesenchyme Neurulation Neural crest. A differential requirement for SUMOylation in proliferating and non-proliferating cells during Drosophila development. Interkinetic nuclear migration is a broadly conserved feature of cell division in pseudostratified epithelia.
Identification and in vivo characterization of NvFP-7R, a developmentally regulated red fluorescent protein of Nematostella vectensis. Cell topology, geometry, and morphogenesis in proliferating epithelia. Current Topics in Developmental Biology. Bicoid by the numbers: The emergence of geometric order in proliferating metazoan epithelia.
Current Opinion in Cell Biology. Lumenal transmission of decapentaplegic in Drosophila imaginal discs. Scientists have researched model organisms such as C. Elegans, and observed reduced senescence in the event of selective mutations in specific genes. However the same result is yet to be reproduced in higher and more complex organisms, hence the elucidation of the exact process remains a mystery.
As more studies are carried out, more theories are put forth to help explain the occurrence of this process, along with ways to prevent and reverse it. Relevant Research Topics Selective telomerase activation to delay senescence Inhibition of mTOR gene and gene products for longevity of life Effects of diet caloric restriction on lifespan Effect of altered energy generation capacity epigenetic changes on the process of aging Effect of reduced mRNA translation on senescence.
The ever-growing human population along with the recent population explosion has caused a dramatic increase in the demand for food crops. This coupled with the occurrence of natural disasters like earthquakes, floods, etc. Such a shortage increases the world's hunger problem, where most of the inhabiting people of developing nations are unable to feed themselves everyday.
To solve such a mammoth crisis, and to avert death of people on account of starvation, the yield of food has to be increased manifold.
One way to do this, can be by upgrading the agricultural practices of farmers; by giving them advanced know-how, better tools and implements, and to have precautions in place to protect the farmed yield from instances of natural disasters and pest populations. Another way to overcome this problem, is to research and produce newer varieties of these food crops that are resistant and even repellent towards pest populations, while at the same time produce a very high yield with minimum care.
Varieties of crops which produce food in more than one season, can also be produced. Relevant Research Topics Development of GMO food crops Development of high-yield varieties of wheat and corn Imparting viral, fungal, and bacterial resistance to crop plants, Study of salt and water stress on plants Inducing production of pest-repellent natural biochemicals e. With the advent of vaccines, anti-microbial, and anti-viral agents, numerous diseases have been eradicated, averted and contained.
Infections that would have proven fatal a few decades ago are now taken care of by a mere injection, tablet, or a capsule, helping in increasing the overall health of the human population. But with the excessive use of antimicrobial solutions, nature serves us a reminder of continuous evolution in the form of antibiotic resistant strains of micro-organisms. As the strength and efficiency of these antibiotics evolves due to medical research, the infectious organisms too evolve and adapt to overcome these substances.
Current Topics in Developmental Biology: Trends in Biochemical Sciences. Any disorder that occurs, is mainly due to a mutation or defect in the gene sequence. Passerines 2-Volume Set 2. Cellular and Molecular Life Sciences. Cell topology, geometry, and morphogenesis in proliferating epithelia.
An infection caused by such an organism is not only untreatable, but also proves to be fatal. To curb this evolution of "super-bugs", newer mechanisms and pathways have to be researched to prevent infections by these organisms. Also, targeted drugs have to be developed that halt the organism's internal processes, thereby rendering it unable to infect. Relevant Research Topics Mechanism of pathogenesis of antibiotic resistant agent Drug designing of molecules that hamper pathogenicity Development of a biomolecule that induces programmed cell death by caspase activation in resistant organism Development of new target models to produce more effective antibiotics Studying effects of probiotics in infection prevention.
Technology has brought the world closer and improved the quality of life considerably. Actions that took extended periods of time, can now be carried out easily and within a short time. There is year round availability of goods in all parts of the world. But such industrial advancement comes with its fair share of adverse consequences. The petroleum industry which provides fuel for so many purposes, has accidents which cause oil spills in oceans.
These affect the natural fauna and flora of the marine ecosystem. The smoke emissions from vehicles and industries cause air pollution, which in turn affects the health of animals and humans equally. The effluents from the factories pollute water bodies, that eventually affect anything and anyone that utilizes the water. These instances are not only hampering the health of organisms but also affecting the physical world in the form of climate change, global warming, and ozone depletion.
Scientists are now working on natural biological ways to rid the environment of such harmful pollutions, and are also devising ways in which the pollution is altered and reduced at their very source. Relevant Research Topics Development of GMO microbes that break down oil Development of eco-friendly fuel alternatives bio-diesel Practical use of bioluminescence in place of electricity Bio-films that absorb air pollution Studying plants water hyacinth and microbes that can absorb heavy and toxic elements from effluents of industries. Cancer is one of the major health concerns in humans.
It is the condition of uncontrolled and abnormal division of body cells. These cells have the potential to spread to other parts of the body, and spread the cancer. Cancer is characterized by the formation of a cell mass called the tumor. There are two types of tumors - benign and metastatic. The benign tumor is just a compact overgrowth of cells that can be easily removed by surgery.