Open-field behaviour in chickens: A replication revisited

In an attempt to show that the open field can still be used as a valid measure of fear, Jones (1983) has reported a failure to replicate some of our findings. The present studies show that this was due to procedural and methodological differences. For instance, we found that birds tested in a novel environment behaved quite differently from those, as in Jones' case, which were placed in one resembling the home cage. Moreover, birds housed in isolation for two days prior to testing reacted differently than those, as again in Jones' case, which were reared in isolation from hatching to the time of testing. The results were interpreted as being consistent with our view that open-field behaviour reflects a conflict between the need to reinstate contact with conspecifics on the one hand, and evade predation on the other.     

Isolation and characterization of an anaerobic benzoate-degrading spore-forming sulfate-reducing bacterium, Desulfotomaculum sapomandens sp. nov.

Abstract Spore-forming sulfate-reducing bacteria (SRB) were enriched selectively from various kinds of aerobic soils with fatty acids as the sole carbon and energy source. A Gram-negative motile rod-shaped bacterium, which produced gas vacuoles during sporulation was isolated. It degraded alcohols, aromatic and n-fatty acids (up to C₁₈) except for propionate, completely to CO₂. Sulfate, sulfite, thiosulfate or elemental sulfur served as electron acceptors. Because of its sensitivity to H₂S, the isolate never produced more than 8 mM dissolved sulfide at pH 7.0. G + C-content of the DNA was 48.0 mol %. The isolated strain Pato is described as a new species Desulfotomaculum sapomandens .     

小鼠肝脏免疫抑制蛋白质(LISP)的分离纯化和鉴定

用硫酸铵分段盐析及DEAE-Sephadex A-50、羟磷灰石和CM纤维素等多种柱层析方法,从正常小鼠肝浸液中分离纯化出一种免疫抑制蛋白质(LISP)。在体外用微量该蛋白质就能强烈抑制小鼠T、B淋巴细胞对促有丝分裂原和同种异型抗原的增生反应。纯化的蛋白质在聚丙烯酰胺凝胶电泳(PACE)和等电聚焦(IEF)鉴定时均显示为一条区带,其等电点(pI)值在7.5—7.8范围。沉降系数利S_(20),w为5.39。Sephadex G-100凝胶层析测得LISP的分子量为78,000道尔顿。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)提示LISP是由二个相同的亚基组成,亚基分子量为38,500道尔顿。LISP是一种既非糖蛋白又非脂蛋白的碱性蛋白质,对它的氨基酸组成也作了分析。     

Lysine biosynthesis and the evolution-of pennate marine diatoms

The classification of lysine biosynthetic pathways in various organisms have been used to investigate their descent in evolution. We have attempted these determinations in the diatoms Amphora coffeaeformis var:perpusilla (Grunow Cleve.) and Phaeodactylum tricornutum (Bohlin). Additionally, we have verified earlier results of Vogel in a green alga, Chlorella pyrenoidosa strain Tx 71105 (Texas Culture Collection). Our research indicates that the diaminopimelic acid route is involved in all three organisms. While these studies do not exclude the possible co-existence of the α-aminoadipic acid route, the results imply a closer evolutionary relationship of pennate diatoms to bacteria and “classical” photosynthetic plants rather than to heterotrophic or mixotrophic fungi and atypical algal strains such as the Euglenophyta.     

S100a0 (αα) Protein Is Present in Neurons of the Central and Peripheral Nervous System

The cellular distribution of S100 subunits in human brain and peripheral nerves was studied by means of an immunohistochemical technique using antibodies specific to the alpha subunit or the beta subunit of S100 protein. The results indicate that the distribution of the alpha subunit and the beta subunit is different among cell types in the nervous tissue, and that neurons in the brain and peripheral nerves contain only the alpha subunit, or S100a0 protein. The subunit distribution also appears to be different at an intracellular level, where the immunoreaction products for the alpha subunit show granular arrangement whereas those for the beta subunit are found diffusely in the cytoplasm.     

Proteins of the Brain Extracellular Fluid: Evidence for Release of S-100 Protein

Abstract: Extracellular protein fractions were obtained (1) by mild, isotonic irrigation of freshly perfused brain tissue; (2) by collection of proteins released into super-fusing medium by physiologically viable slices of rat hippocampus; and (3) by sampling the CSF of anesthetized rats. Analysis of the S-100 protein content of these fractions gave values of 2.8, 4.2, and 1.8 μg S-100/mg protein, respectively. These values were three- to sixfold higher than the S-100 content of the soluble cytoplasmic protein fractions from the same tissue. This several-fold higher S-100 content of the extracellular protein fractions relative to the intracellular cytoplasmic protein fractions indicates that S-100 is selectively released into the extracellular spaces of the brain. We suggest that the biological function of this CNS protein may involve intercellular transfer.     

Hormonal Regulation of Adipose S-100 Protein Release

The release of S-100 protein from epididymal fat pads was enhanced by epinephrine in vitro, and about 50% of S-100 protein in the tissue was released into the medium after 2-h incubation at 37 degrees C with 10 microM epinephrine. Similar results were obtained with the incubation of isolated adipocytes. The S-100 protein release was also enhanced by isoproterenol, norepinephrine, ACTH, and dibutyryl cyclic AMP, which all increase the lipolysis by increasing cyclic AMP levels in the tissue. Propranolol, a beta-adrenergic blocker, could block the increase of S-100 protein release by catecholamines, indicating that the release was mediated by the beta-adrenergic effect of catecholamines. However propranolol had no suppressive effect on the enhancement of S-100 protein release by ACTH or dibutyryl cyclic AMP. Insulin had an inhibitory effect on the epinephrine-enhanced S-100 protein release. Epinephrine or ACTH could not stimulate the S-100 protein release in the absence of Ca2+, whereas the epinephrine-enhanced glycerol release was not affected under the same conditions. The increase in S-100 protein release was induced by only a pretreatment of the tissue with epinephrine. However, the lipolysis in the tissue was not enhanced by the pretreatment alone. These results indicate that the release of S-100 protein from adipocytes is regulated by the hormones that have been known to control the lipolysis with a manner slightly different from that of lipolysis.     

Mathematical modelling of dynamics and control in metabolic networks. II. Simple dimeric enzymes

The dynamics of enzyme cooperativity are examined by studying a homotropic dimeric enzyme with identical reaction sites, both of which follow irreversible Michaelis-Menten kinetics. The problem is approached via scaling and linearization of the governing mass action kinetic equations. Homotropic interaction between the two sites are found to depend on three dimensionless groups, two for the substrate binding step and one for the chemical transformation. The interaction between the two reaction sites is shown capable of producing dynamic behavior qualitatively different from that of a simple Michaelis-Menten system; when the two sites interact to increase enzymatic activity over that of two independent monomeric enzymes (positive cooperativity) damped oscillatory behavior is possible, and for negative cooperativity in the chemical transformation step a multiplicity of steady states can occur, with one state unstable and leading to runaway behavior. Linear analysis gives significant insight into system dynamics, and their parametric sensitivity, and a way to identify regions of the parameter space where the approximate quasi-stationary and quasi-equilibrium analyses are appropriate.