Kenneth Mellanby

Bio: Kenneth Mellanby is an academic researcher from University of London. The author has contributed to research in topics: Pollution & Humidity. The author has an hindex of 20, co-authored 57 publications receiving 1120 citations.

Man's Reaction to Mosquito Bites.

Abstract: IT is widely known that different individuals give very different reactions to the bites of insects, and also that repeated exposure may a ter the reactions of one individual (Boycott1, Hecht2), but surprisingly little work has been done on this subject. The availability of a group of human volunteer subjects for medical research made it possible to investigate the effect of the bites of various species on individuals who could be kept under observation for long periods.

Ecology of human skin

Abstract: Do you ever know the book? Yeah, this is a very interesting book to read. As we told previously, reading is not kind of obligation activity to do when we have to obligate. Reading should be a habit, a good habit. By reading, you can open the new world and get the power from the world. Everything can be gained through the book. Well in brief, book is very powerful. As what we offer you right here, this ecology of the human skin is as one of reading book for you.

Acclimatization and the Thermal Death Point in Insects

Abstract: INSECTS, like other cold-blooded animals, are active over a range of temperature, limited below by the chill coma point, and above by the heat coma point (closely related to the thermal death point, that is, the upper lethal temperature, for they cannot recover from long periods of heat coma). On the whole, the heat coma point is higher for insects from warm regions, and the chill coma point is lower in those from cool regions.

The Site of Loss of Water from Insects

Abstract: A considerable amount of work has been done with regard to the water-balance of insects (recently summarized by Buxton, 1932), and on the physical laws governing the water loss from insects, but as yet no one has determined exactly from what part of the insect’s body water is lost. It has been found that when insects are not excreting at all, considerable amounts of water are evaporated from their bodies—quantities frequently sufficient to cause death from desiccation. There are three possible ways in which an insect might lose this water (apart from the alimentary canal) : (i) through the general surface of the body wall; (ii) through the spiracular system; and (iii) partly from the body surface and partly through the spiracular system. The fact that carbon dioxide passes readily through chitin (Dewitz, 1890), and that insects get rid of some of that gas through their integument (v. Buddenbrock and Rohr, 1922), suggests that watervapour may also pass from the insect's body in a similar manner. However, Hazelhoff (1927) states that resting insects keep their spiracles closed most of the time, only opening them sufficiently often to obtain enough oxygen, in order to conserve water. He believes that most of the water is lost through the tracheal system. The observations of Gunn (1933) on the cockroach and Mellanby (1932, b ) on the mealworm also suggest that a high proportion of the water evaporated from those insects is lost through the spiracles. The experiments described in this paper show how spiracular opening affects the rate at which insects lose water by evaporation, and the results obtained make it possible to say from what parts of the body this loss takes place.

Prokaryotes: The unseen majority

Abstract: The number of prokaryotes and the total amount of their cellular carbon on earth are estimated to be 4-6 3 10 30 cells and 350-550 Pg of C (1 Pg 5 10 15 g), respectively. Thus, the total amount of prokaryotic carbon is 60-100% of the estimated total carbon in plants, and inclusion of prokaryotic carbon in global models will almost double estimates of the amount of carbon stored in living organisms. In addition, the earth's prokaryotes contain 85-130 Pg of N and 9-14 Pg of P, or about 10-fold more of these nutrients than do plants, and represent the largest pool of these nutrients in living organisms. Most of the earth's prokaryotes occur in the open ocean, in soil, and in oceanic and terrestrial subsurfaces, where the numbers of cells are 1.2 3 10 29 , 2.6 3 10 29 , 3.5 3 10 30 , and 0.25-2.5 3 10 30 , respectively. The numbers of het- erotrophic prokaryotes in the upper 200 m of the open ocean, the ocean below 200 m, and soil are consistent with average turnover times of 6-25 days, 0.8 yr, and 2.5 yr, respectively. Although subject to a great deal of uncertainty, the estimate for the average turnover time of prokaryotes in the subsurface is on the order of 1-2 3 10 3 yr. The cellular production rate for all prokaryotes on earth is estimated at 1.7 3 10 30 cellsyyr and is highest in the open ocean. The large population size and rapid growth of prokaryotes provides an enormous capacity for genetic diversity. Although invisible to the naked eye, prokaryotes are an essential component of the earth's biota. They catalyze unique and indispensable transformations in the biogeochemical cy- cles of the biosphere, produce important components of the earth's atmosphere, and represent a large portion of life's genetic diversity. Although the abundance of prokaryotes has been estimated indirectly (1, 2), the actual number of pro- karyotes and the total amount of their cellular carbon on earth have never been directly assessed. Presumably, prokaryotes' very ubiquity has discouraged investigators, because an esti- mation of the number of prokaryotes would seem to require endless cataloging of numerous habitats. To estimate the number and total carbon of prokaryotes on earth, several representative habitats were first examined. This analysis indicated that most of the prokaryotes reside in three large habitats: seawater, soil, and the sedimentysoil subsur- face. Although many other habitats contain dense populations, their numerical contribution to the total number of pro- karyotes is small. Thus, evaluating the total number and total carbon of prokaryotes on earth becomes a solvable problem. Aquatic Environments. Numerous estimates of cell density, volume, and carbon indicate that prokaryotes are ubiquitous in marine and fresh water (e.g., 3-5). Although a large range of cellular densities has been reported (10 4 -10 7 cellsyml), the

Iron deficiency limits phytoplankton growth in the north-east Pacific subarctic

Abstract: An interesting oceanographic problem concerns the excess major plant nutrients (PO4, NO3, SiO3) occurring in offshore surface waters of the Antarctic1–3 and north-east Pacific subarctic Oceans4 In a previous study5, we presented indirect evidence suggesting that inadequate Fe input was responsible for this limitation of growth; recently we had the opportunity to seek direct evidence for this hypothesis in the north-east Pacific subarctic We report here that the addition of nmol amounts of dissolved iron resulted in the nearly complete utilization of excess NO3, whereas in the controls—without added Fe—only 25% of the available NO3 was used We also observed that the amounts of chlorophyll in the phytoplankton increased in proportion to the Fe added We conclude that Fe deficiency is limiting phytoplankton growth in these major-nutrient-rich waters

glacial-interglacial Co2 change : the iron hypothesis

Abstract: Several explanations for the 200 to 280 ppm glacial/interglacial change in atmospheric CO2 concentrations deal with variations in southern ocean phytoplankton productivity and the related use or nonuse of major plant nutrients. An hypothesis is presented herein in which arguments are made that new productivity in today's southern ocean (7.4 × 1013g yr−1) is limited by iron deficiency, and hence the phytoplankton are unable to take advantage of the excess surface nitrate/phosphate that, if used, could result in total southern ocean new production of 2−3 × 1015 g C yr−1. As a consequence of Fe-limited new productivity, Holocene interglacial CO2 levels (preindustrial) are as high as they were during the last interglacial (≈ 280 ppm). In contrast, atmospheric dust Fe supplies were 50 times higher during the last glacial maximum (LGM). Because of this Fe enrichment, phytoplankton growth may have been greatly enhanced, larger amounts of upwelled nutrients may have been used, and the resulting stimulation of new productivity may have contributed to the LGM drawdown of atmospheric CO2 to levels of less than 200 ppm. Background information and arguments in support of this hypothesis are presented.

Acidic extracellular microenvironment and cancer

Abstract: Acidic extracellular pH is a major feature of tumor tissue, extracellular acidification being primarily considered to be due to lactate secretion from anaerobic glycolysis. Clinicopathological evidence shows that transporters and pumps contribute to H+ secretion, such as the Na+/H+ exchanger, the H+-lactate co-transporter, monocarboxylate transporters, and the proton pump (H+-ATPase); these may also be associated with tumor metastasis. An acidic extracellular pH not only activates secreted lysosomal enzymes that have an optimal pH in the acidic range, but induces the expression of certain genes of pro-metastatic factors through an intracellular signaling cascade that is different from hypoxia. In addition to lactate, CO2 from the pentose phosphate pathway is an alternative source of acidity, showing that hypoxia and extracellular acidity are, while being independent from each other, deeply associated with the cellular microenvironment. In this article, the importance of an acidic extracellular pH as a microenvironmental factor participating in tumor progression is reviewed.

A diversity profile of the human skin microbiota

Abstract: The many layers and structures of the skin serve as elaborate hosts to microbes, including a diversity of commensal and pathogenic bacteria that contribute to both human health and disease. To determine the complexity and identity of the microbes inhabiting the skin, we sequenced bacterial 16S small-subunit ribosomal RNA genes isolated from the inner elbow of five healthy human subjects. This analysis revealed 113 operational taxonomic units (OTUs; "phylotypes") at the level of 97% similarity that belong to six bacterial divisions. To survey all depths of the skin, we sampled using three methods: swab, scrape, and punch biopsy. Proteobacteria dominated the skin microbiota at all depths of sampling. Interpersonal variation is approximately equal to intrapersonal variation when considering bacterial community membership and structure. Finally, we report strong similarities in the complexity and identity of mouse and human skin microbiota. This study of healthy human skin microbiota will serve to direct future research addressing the role of skin microbiota in health and disease, and metagenomic projects addressing the complex physiological interactions between the skin and the microbes that inhabit this environment.