Rockefeller University

About: Rockefeller University is a education organization based out in New York, New York, United States. It is known for research contribution in the topics: Population & Gene. The organization has 15867 authors who have published 32938 publications receiving 2940261 citations. The organization is also known as: Rockefeller University & Rockefeller Institute.

Ecological community description using the food web, species abundance, and body size

Abstract: Measuring the numerical abundance and average body size of individuals of each species in an ecological community's food web reveals new patterns and illuminates old ones This approach is illustrated using data from the pelagic community of a small lake: Tuesday Lake, Michigan, United States Body mass varies almost 12 orders of magnitude Numerical abundance varies almost 10 orders of magnitude Biomass abundance (average body mass times numerical abundance) varies only 5 orders of magnitude A new food web graph, which plots species and trophic links in the plane spanned by body mass and numerical abundance, illustrates the nearly inverse relationship between body mass and numerical abundance, as well as the pattern of energy flow in the community Species with small average body mass occur low in the food web of Tuesday Lake and are numerically abundant Larger-bodied species occur higher in the food web and are numerically rarer Average body size explains more of the variation in numerical abundance than does trophic height The trivariate description of an ecological community by using the food web, average body sizes, and numerical abundance includes many well studied bivariate and univariate relationships based on subsets of these three variables We are not aware of any single community for which all of these relationships have been analyzed simultaneously Our approach demonstrates the connectedness of ecological patterns traditionally treated as independent Moreover, knowing the food web gives new insight into the disputed form of the allometric relationship between body mass and abundance

The light and dark sides of intestinal intraepithelial lymphocytes

Abstract: The intraepithelial lymphocytes (IELs) that reside within the epithelium of the intestine form one of the main branches of the immune system. As IELs are located at this critical interface between the core of the body and the outside environment, they must balance protective immunity with an ability to safeguard the integrity of the epithelial barrier: failure to do so would compromise homeostasis of the organism. In this Review, we address how the unique development and functions of intestinal IELs allow them to achieve this balance.

Influence of Matrix Solution Conditions on the MALDI-MS Analysis of Peptides and Proteins

Abstract: Sample−matrix preparation procedures are shown to greatly influence the quality of the matrix-assisted laser desorption/ionization (MALDI) mass spectra of peptides and proteins. In particular, dramatic mass discrimination effects are observed when the matrix 4-hydroxy-α-cyanocinnamic acid is used for analyzing complex mixtures of peptides and proteins. The discrimination effects are found to be strongly dependent on the sample−matrix solution composition, pH, and the rates at which the sample−matrix cocrystals are grown. These findings demonstrate the need to exercise great care in performing and interpreting the MALDI analysis of biological samples. The results also indicate that there is a reverse-phase chromatographic-like dimension in the sample−matrix preparation procedures that can be exploited to optimize the analysis. The present work describes the conditions under which the majority of components of a complex mixture of peptides and proteins can be successfully measured.

Synaptic physiology of horizontal connections in the cat's visual cortex

Abstract: Horizontal connections are a principal component of intrinsic cortical circuitry. They arise mainly from pyramidal cells and course parallel to the brain9s surface for distances as long as 8 mm, linking columns with shared orientation preference and allowing cells to integrate visual information from outside their receptive fields. We examined the synaptic physiology of the horizontal pathway in slices of the cat9s striate cortex and found that activating lateral fibers produced both excitation and inhibition. We recorded the postsynaptic responses of identified pyramidal cells in layer 2 + 3 of area 17 to electrical shocks applied at three sites: in the home column of the impaled neuron either in layer 2 + 3 or 4, or at a lateral distance of 0.9–3 mm in layer 2 + 3. Within the home column, suprathreshold stimuli produced compound EPSPs with action potentials, followed by fast, GABAAergic IPSPs and a slower, GABABergic IPSP. For the distant stimulating site, the threshold response was an EPSP. Stronger shocks frequently evoked a disynaptic, GABAAergic IPSP that truncated the EPSP and could dominate the postsynaptic response. At the resting potential, the horizontally evoked EPSP was too small to elicit spikes. With depolarization of the membrane, however, it grew several hundred-fold. This amplification was blocked by N-(2,6-dimethylphenylcarbamoylmethyl)triethylammonium bromide (QX-314), but not by 2-amino-5-phosphonovalerate (APV), indicating that it was mediated by Na+ channels, rather than by NMDA receptors. We propose that the horizontal connections provide the means for stimuli outside the receptive field to modulate activity elicited within its confines. The voltage-dependent enhancement of the laterally evoked EPSP may explain why stimulating the surround by itself fails to drive cells but can facilitate their response to stimuli within the receptive field. The ability to initiate disynaptic inhibition from lateral sites shows that recruiting appropriate groups of horizontal fibers can also have a suppressive effect. Thus, the effect of horizontal input is state dependent, with the size and sign of the laterally evoked response changing according to the balance of converging inputs.