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.

Effects of Varying the Vehicle for OsO4 in Tissue Fixation

Abstract: I t is well known that the quality of OsO4 fixation of tissue cells obtained with any one of the several recommended mixtures (1-3) may vary considerably in the same block or from one tissue to another. In some cells of a sample, the material of the cytoplasmic matrix may appear as an even distribution of partides and finely fibrous elements, in which case it is regarded as well fixed. In other cells in the same sample the matrix components may be condensed into clumps of variable size and density, separated by areas of lesser density devoid of any resolvable structure. Such clumping is usually taken as descriptive of relatively poor fixation, since little or no evidence of it can be detected in equivalent living cells (4). I t has been noted also that in images of what one considers to be well fixed ceils, the contours of the membrane-limited elements of the endoplasmic reticulum are smooth, whereas in another part of the same preparation equivalent structures may appear angular or irregular and vesiculate& In some images the nucleoplasm is homogeneous and relatively uniform in density, whereas in others it is obviously uneven and coagulated. Some of these differences may be referable to structural or compositional variations associated with functional changes, but in most instances the differences seem more properly considered as products of fixation. Especially is this true in frequent

Multivalent engagement of chromatin modifications by linked binding modules.

Abstract: Various chemical modifications on histones and regions of associated DNA play crucial roles in genome management by binding specific factors that, in turn, serve to alter the structural properties of chromatin. These so-called effector proteins have typically been studied with the biochemist's paring knife--the capacity to recognize specific chromatin modifications has been mapped to an increasing number of domains that frequently appear in the nuclear subset of the proteome, often present in large, multisubunit complexes that bristle with modification-dependent binding potential. We propose that multivalent interactions on a single histone tail and beyond may have a significant, if not dominant, role in chromatin transactions.

Liver-enriched transcription factor HNF-4 is a novel member of the steroid hormone receptor superfamily.

Abstract: HNF-4 (hepatocyte nuclear factor 4) is a protein enriched in liver extracts that binds to sites required for the transcription of the genes for transthyretin (TTR), the carrier protein in the serum for vitamin A and thyroid hormone, and for apolipoprotein CIII (apoCIII), a major constituent of chylomicrons and very low-density lipoproteins (VLDL) Synthetic oligonucleotides derived from amino acid sequence of affinity-purified HNF-4 protein (54 kD) were used in the polymerase chain reaction (PCR) to isolate a cDNA clone encoding the protein HNF-4 is a member of the steroid hormone receptor superfamily with an unusual amino acid in the conserved "knuckle" of the first zinc finger (DGCKG) Studies with in vitro-translated HNF-4 protein show that it binds to its recognition site as a dimer, and cotransfection assays indicate that it activates transcription in a sequence-specific fashion in nonhepatic (HeLa) cells Northern blot analysis reveals that HNF-4 mRNA is present in kidney and intestine, as well as liver, but is absent in other tissues DNA-binding and antisera reactivity data suggest that HNF-4 could be identical to liver factor A1 (LF-A1), a DNA-binding activity implicated in the regulation of transcription of the alpha 1-antitrypsin, apolipoprotein A1, and pyruvate kinase genes The similarity between HNF-4 and other ligand-dependent transcription factors raises the possibility that HNF-4 and the genes it regulates respond to an as yet unidentified ligand

Human dendritic cells activate resting natural killer (NK) cells and are recognized via the NKp30 receptor by activated NK cells.

Abstract: During the innate response to many inflammatory and infectious stimuli, dendritic cells (DCs) undergo a differentiation process termed maturation. Mature DCs activate antigen-specific naive T cells. Here we show that both immature and mature DCs activate resting human natural killer (NK) cells. Within 1 wk the NK cells increase two– to fourfold in numbers, start secreting interferon (IFN)-γ, and acquire cytolytic activity against the classical NK target LCL721.221. The DC-activated NK cells then kill immature DCs efficiently, even though the latter express substantial levels of major histocompatibility complex (MHC) class I. Similar results are seen with interleukin (IL)-2–activated NK cell lines and clones, i.e., these NK cells kill and secrete IFN-γ in response to immature DCs. Mature DCs are protected from activated NK lysis, but lysis takes place if the NK inhibitory signal is blocked by a human histocompatibility leukocyte antigen (HLA)-A,B,C–specific antibody. The NK activating signal mainly involves the NKp30 natural cytotoxicity receptor, and not the NKp46 or NKp44 receptor. However, both immature and mature DCs seem to use a NKp30 independent mechanism to act as potent stimulators for resting NK cells. We suggest that DCs are able to control directly the expansion of NK cells and that the lysis of immature DCs can regulate the afferent limb of innate and adaptive immunity.