Hasil untuk "Biology"

Shenghong Ma, Z. Meng, Rui Chen et al.

The Hippo pathway was initially discovered in Drosophila melanogaster as a key regulator of tissue growth. It is an evolutionarily conserved signaling cascade regulating numerous biological processes, including cell growth and fate decision, organ size control, and regeneration. The core of the Hippo pathway in mammals consists of a kinase cascade, MST1/2 and LATS1/2, as well as downstream effectors, transcriptional coactivators YAP and TAZ. These core components of the Hippo pathway control transcriptional programs involved in cell proliferation, survival, mobility, stemness, and differentiation. The Hippo pathway is tightly regulated by both intrinsic and extrinsic signals, such as mechanical force, cell-cell contact, polarity, energy status, stress, and many diffusible hormonal factors, the majority of which act through G protein-coupled receptors. Here, we review the current understanding of molecular mechanisms by which signals regulate the Hippo pathway with an emphasis on mechanotransduction and the effects of this pathway on basic biology and human diseases.

M. Menezes

Normal cells make up tissues, and when these cells lose their ability to behave as a specified, controlled and coordinated unit (dedifferentiation) the defect leads to disarray amongst the cell population. When this occurs, a tumor is formed. (More about this later.) Cancer is a term describing a large variety of disorders of proliferation. The specific disorder may vary from tissue type to tissue type. A single tumor may even have different populations of cells within it with differing processes that have gone awry.

H. Sies

“Oxidative stress” as a concept in redox biology and medicine has been formulated in 1985; at the beginning of 2015, approx. 138,000 PubMed entries show for this term. This concept has its merits and its pitfalls. Among the merits is the notion, elicited by the combined two terms of (i) aerobic metabolism as a steady-state redox balance and (ii) the associated potential strains in the balance as denoted by the term, stress, evoking biological stress responses. Current research on molecular redox switches governing oxidative stress responses is in full bloom. The fundamental importance of linking redox shifts to phosphorylation/dephosphorylation signaling is being more fully appreciated, thanks to major advances in methodology. Among the pitfalls is the fact that the underlying molecular details are to be worked out in each particular case, which is bvious for a global concept, but which is sometimes overlooked. This can lead to indiscriminate use of the term, oxidative stress, without clear relation to redox chemistry. The major role in antioxidant defense is fulfilled by antioxidant enzymes, not by small-molecule antioxidant compounds. The field of oxidative stress research embraces chemistry, biochemistry, cell biology, physiology and pathophysiology, all the way to medicine and health and disease research.

A. Hyman, C. Weber, F. Jülicher

S. E. Andaloussi, Imre Mäger, X. Breakefield et al.

C. Conrath

The rôle of fsh in the ovine cycle is still uncertain because of the scarcity of information concerning plasma levels. The aim of this communication is to describe the development of a radioimmunoassay (RIA) for ovine fsh (ofsh) and to give an account of the technical difficulties associated with assays in ovine plasma. A solid phase radioimmunoassay similar to that described for ovine luteinizing hormone (lh) by Goding, Catt, Brown, Kaltenbach, Cumming & Mole (1969) has been developed for the measurement of ovine and bovine prolactin over the range 2 to 200 ng/ml in plasma. in standard When eight separate prolactin + 0-9, + 39-6 172 + 31-7, between-assay coefficient of variation 21 externa follicles functional rôle in The in vitro metabolism of glucose by preimplantation mouse embryos was studied by measuring the incorporation of [U-14C]glucose into the embryo during culture. Twice-washed eight-cell and morula stage embryos were cul¬ tured for 24 hr in medium containing 5-56 mM glucose (3 µ /µ ) as the sole energy substrate. The embryos were recovered after incubation, washed free from the culture medium and various biochemical components were ex¬ tracted using standard techniques. between two developmental stages studied. acid-soluble a substantial in the proportion of glucose incorporated into glycogen at the stage of development. the acid-insoluble that the glucose carbon was incorporated into the DNA, RNA, lipid and protein of the embryo. Incorporation into DNA represented 20 % of the total label in both the eight-cell and the morula. The RNA extract accounted for a greater propor¬ tion of the total uptake of label in morulae (16%) than in eight-cell embryos (13%), suggesting an increase in RNA synthesis with development. The accumulation of label into lipid material was shown to decrease in these de¬ velopmental stages from 5 % in the eight-cell embryo to 2 % in morulae. The lipid extract was separated into neutral and phospholipid classes by silicic acid chromatography. The majority of the labelled lipid was found to be neutral in character with phospholipid only accounting for 26 % of the label in this frac¬ tion. The accumulation of label in the protein fraction was also observed to decrease from 18% at the eight-cell stage to 12 % at the morula stage. The culture medium was recovered after incubation and an extracellular accumulation of labelled basic and acidic compounds was found. Lactate accounted for 66 to 87 % of the labelled carboxylic acids with the majority of the remainder consisting of pyruvate and acetate. Trace amounts ofmalate and citrate were also present. suggest Degenerative changes in the testis produced by acute and chronic heating have been frequently described but the recovery process is not well documented. Testicular degeneration was produced in the rat by heating the scrotal testis in water at 42° C for 30 min, or by abdominal retention (cryptorchism) of one testis for 2 weeks. The recovery period for acute heating (42° C) was arbitrarily taken from 1 week after heating, and for cryptorchism from release of the retained testis. Standard haematoxylin and eosin methods were used for histological assessment and enzyme staining, including acid phosphatase, was performed on frozen sections. Two-way selection for twin births in Merino ewes has resulted in flocks of low (S flock), medium (T flock) and high (B flock) fecundity. The ovarian response to exogenous gonadotrophin by these ewes was examined with a view to establishing the nature ofthe endocrine changes that have accompanied the divergence in fecundity. determine the effects of colchicine-induced embryonic death in early pregnancy on cycle and progesterone levels in dilutions of sera, followed by separation of the free from bound [1251] antigen with Injection of the coupled derivatives of formononetin, daidzein and genistein have led to formation of appreciable antibody titres in twenty-five of the twenty-seven sheep treated. Free phyto-oestrogens and steroid oestrogens were tested for inhibition of the [125I]antigen-antibody reaction. The results showed that the antibodies raised in the sera had a high specificity for the particular phyto-oestrogen whose derivative was coupled with the albumin. Thus, the antibodies raised with formononetin-2-carboxylic acid-bovine serum albumin reacted with formononetin but there was little or no cross-reaction with genis¬ and no measurable cross-reaction or The time course of [3H]oestradiol-17/J uptake by the mouse vagina following intravaginal administration was studied. The distribution of [3H]oestradiol between 800 g and 105,000 g supernatant fractions of the vaginal homogenates and the binding of [3H]oestradiol by these fractions were examined to follow possible changes in the interactions of oestradiol with oestrogen receptors in these two subcellular locations. Approximately 60% of the radioactivity in the nuclear fraction was solubilized in a bound form by a single extraction with tris-EDTA buffer, pH 8-5, containing 0-4 m-KCL. [3H]Oestradiol-binding in the supernatant fraction and in nuclear extracts was studied by sucrose density gradient centrifugation and charcoal adsorption. Non-specific binding was differentiated with the sulphydryl group inhibitor, /»-hydroxymercuribenzoate incubate, or an extract, was partitioned between chloroform and water, and the radioactivity in each phase measured. The chase dose decreased the total radioactivity in the nucleus at both times. The proportion of radioactivity in the nuclear fraction which was associated with the water phase was greater with the 64-min chase dose. These preliminary results suggest that there was either a direct competition between these two forms of oestradiol within the nucleus or that there was considerable recycling of oestradiol between the two tissue fractions. The pituitary and ovarian responses to the injection of oestradiol benzoate (ODB) or testosterone propionate (TP) were examined in lactating Merino ewes during March 1971. The of ewes were laparotomy 5 days after treatment. Plasma samples, obtained from five ewes from each the six period 38 hr after treatment, were assayed for lh content. the immunological actions of the possible participation of the in a local 'hormone initial the effect of hcg on in vitro phyto-haemagglu-tinin (PHA)-induced lymphocyte transformation. Lymphocyte were established using standard techniques and hcg was added to seventeen test in a concentration of 30 i.u./l ml This concentration corres¬

Cedric R. Clapier, B. Cairns

Simeone Marino, Ian B. Hogue, Christian Ray et al.

J. Werren, L. Baldo, M. E. Clark

G. Trinchieri

Studies of cytotoxicity by human lymphocytes revealed not only that both allogeneic and syngeneic tumor cells were lysed in a non-MHC-restricted fashion, but also that lymphocytes from normal donors were often cytotoxic. Lymphocytes from any healthy donor, as well as peripheral blood and spleen lymphocytes from several experimental animals, in the absence of known or deliberate sensitization, were found to be spontaneously cytotoxic in vitro for some normal fresh cells, most cultured cell lines, immature hematopoietic cells, and tumor cells. This type of nonadaptive, non-MHC-restricted cellmediated cytotoxicity was defined as “natural” cytotoxicity, and the effector cells mediating natural cytotoxicity were functionally defined as natural killer (NK) cells. The existence of NK cells has prompted a reinterpretation of both the studies of specific cytotoxicity against spontaneous human tumors and the theory of immune surveillance, at least in its most restrictive interpretation. Unlike cytotoxic T cells, NK cells cannot be demonstrated to have clonally distributed specificity, restriction for MHC products at the target cell surface, or immunological memory. NK cells cannot yet be formally assigned to a single lineage based on the definitive identification of a stem cell, a distinct anatomical location of maturation, or unique genotypic rearrangements.

A. Bendelac, P. Savage, L. Teyton

P. Chambon

B. McEwen, J. Wingfield

F. Brauer, C. Castillo-Chavez

W. Smith, D. Dewitt, R. Garavito

M. Tessier-Lavigne, C. Goodman

B. Freeman, J. Crapo

I. Fridovich

Zhi-zhen Wang

Fernando Monroy, Manuel Aira, Jorge Domínguez et al.

Population dynamics methodology now powerfully combines discrete time models (with constant parameters, density dependence, random environment, and/or demographic stochasticity) and capture–recapture models for estimating demographic parameters. Vertebrate population dynamics has strongly benefited from this progress: survival estimates have been revised up-wards, trade-offs between life history traits have been demonstrated, analyses of population viability and management are more and more realistic. Promising developments concern random effects, multistate and integrated models. Some biological questions (density dependence, links between individual and population levels, and diversification of life histories) can now be efficiently attacked. To cite this article: J.-D. Lebreton, C. R. Biologies 329 (2006). ©