Changes in some marker enzyme activities of liver plasma membranes during regeneration after partial hepatectomy in rats.

Liver plasma membranes were isolated from regenerating rat livers between 20 h and 10 days after partial hepatectomy in order to study the effect of partial hepatectomy on some membrane enzyme activities. Mg2+-ATPase (EC 3.6.1.4) activity, but not (Na+ + K+)-ATPase activity, decreased slightly at 2 days, whereas leucyl beta-naphthylamidase (EC3.4.1.1) and 5'-nucleotidase (EC3.1.3.5) activities increased considerably at 1-2 and 3-5 days, respectively. These changes were not parallel to a sharp increase in mitotic activity of liver cells which occurred at 36 h.     

Stereoselective Synthesis of (S,E)-6-Isopropyl-3,9-dimethyl-5,8-decadienyl Acetate,the (S)-Enantiomer of the Yellow Scale Pheromone

The (S)-enantiomer of the sex pheromone of the yellow scale (Aonidiella citrina), (S,E)-6-isopropyl-3,9-dimethyl-5,8-decadienyl acetate, was stereoselectively synthesized from (R)-(+)-citronellic acid.     

Recognition of rat liver and kidney nuclear T3 receptors by an antibody against c-erb A peptide

It has been reported that c-erb A encodes nuclear T3 receptors (NT3R). Based on the sequence of c-erb A cDNA, we synthesized a polypeptide consisting of 15 amino acids, the sequence of which has high homology between c-erb A alpha 1 and beta. The antibody against this c-erb A peptide not only immunoprecipitated rat liver and kidney NT3R but also inhibited T3 binding to NT3R. In a displacement study, the inhibition of [125I]T3-binding by the antibody was parallel to that by T3 in terms of the concentration of the competitor added in the incubation mixture. Scatchard analysis revealed that the antibody decreased the value for the association constant in a dose dependent manner. The antibody did not bind T3 itself. The results show that the antibody against c-erb A peptide recognizes rat liver and kidney NT3R and that the sequence encoding this peptide, the closest carboxyl-terminal of c-erb A may be critical or at least closely related to the hormone binding.     

A simple method for observation of phagocytosis on bacterial thin-layer

A simple method was developed to visually present the phagocytic activity of leukocytes by using adherent Staphylococcus aureus cells and blood applied on a plastic dish. When heparinized blood was applied on thin-layer of heat-killed S. aureus cells on the plastic dish, plaques due to the phagocytic activity of leukocytes were observed with a microscope under a low magnification. Fewer and smaller plaques were observed when plasma-deprived rather than whole blood was used. Some analyses were made in respect to the fundamental conditions required for optimal results. This method was considered to be useful for conveniently evaluating the serum opsonin activities and phagocytic function of leukocytes in various kinds of diseases.     

Arabidopsis Raf‐like kinases act as positive regulators of subclass III SnRK2 in osmostress signaling

Given their sessile nature, land plants must use various mechanisms to manage dehydration under water‐deficit conditions. Osmostress‐induced activation of the SNF1‐related protein kinase 2 (SnRK2) family elicits physiological responses such as stomatal closure to protect plants during drought conditions. With the plant hormone ABA receptors [PYR (pyrabactin resistance)/PYL (pyrabactin resistance‐like)/RCAR (regulatory component of ABA receptors) proteins] and group A protein phosphatases, subclass III SnRK2 also constitutes a core signaling module for ABA, and osmostress triggers ABA accumulation. How SnRK2 is activated through ABA has been clarified, although its activation through osmostress remains unclear. Here, we show that Arabidopsis ABA and abiotic stress‐responsive Raf‐like kinases (AtARKs) of the B3 clade of the mitogen‐activated kinase kinase kinase (MAPKKK) family are crucial in SnRK2‐mediated osmostress responses. Disruption of AtARKs in Arabidopsis results in increased water loss from detached leaves because of impaired stomatal closure in response to osmostress. Our findings obtained in vitro and in planta have shown that AtARKs interact physically with SRK2E, a core factor for stomatal closure in response to drought. Furthermore, we show that AtARK phosphorylates S171 and S175 in the activation loop of SRK2E in vitro and that Atark mutants have defects in osmostress‐induced subclass III SnRK2 activity. Our findings identify a specific type of B3‐MAPKKKs as upstream kinases of subclass III SnRK2 in Arabidopsis. Taken together with earlier reports that ARK is an upstream kinase of SnRK2 in moss, an existing member of a basal land plant lineage, we propose that ARK/SnRK2 module is evolutionarily conserved across 400 million years of land plant evolution for conferring protection against drought.     

Composition of uterine milk and its changes with gestational period in red stingrays (Hemitrygon akajei)

Uterine milk is secreted in the uterus for embryo nutrition in several elasmobranch species and may contribute to rapid embryonic growth, but the details of its composition and its functions are poorly understood. In this study, to explore the roles of uterine milk for embryos, its components throughout the gestational period were analysed in detail. Uterine milk was collected from pregnant red stingrays (Hemitrygon akajei) in the early, middle and late gestational periods, respectively (n= 3 for each period). The crude composition, constituent proteins and fatty acids in the milk were analysed. The uterine milk was rich in proteins throughout the gestational period, whereas lipids dramatically increased in the middle period and reduced slightly towards the late period. Some proteins potentially associated with nutrition, cartilage growth and embryonic immunity were found. Several enzymes related to central metabolism were also detected. The constituent fatty acids in the middle and late periods were similar to those in the egg yolks of elasmobranchs, except for C18:2, which was rich only in the uterine milk. The most abundant fatty acid in the milk was C16:1, which could function as a lipokine to promote lipid metabolism in the embryo. This study's data suggest that uterine milk may be secreted in addition to the egg yolk in elasmobranchs to support rapid and healthy embryonic growth.     

Bursty Communication Patterns Facilitate Spreading in a Threshold-Based Epidemic Dynamics

Records of social interactions provide us with new sources of data for understanding how interaction patterns affect collective dynamics. Such human activity patterns are often bursty, i.e., they consist of short periods of intense activity followed by long periods of silence. This burstiness has been shown to affect spreading phenomena; it accelerates epidemic spreading in some cases and slows it down in other cases. We investigate a model of history-dependent contagion. In our model, repeated interactions between susceptible and infected individuals in a short period of time is needed for a susceptible individual to contract infection. We carry out numerical simulations on real temporal network data to find that bursty activity patterns facilitate epidemic spreading in our model.     

Numerical Simulation of Passage of a Neutrophil through a Rectangular Channel with a Moderate Constriction

The authors have previously presented a mathematical model to predict transit time of a neutrophil through an alveolar capillary segment which was modeled as an axisymmetric arc-shaped constriction settled in a cylindrical straight pipe to investigate the influence of entrance curvature of a capillary on passage of the cell. The axially asymmetric cross section of a capillary also influences the transit time because it requires three-dimensional deformation of a cell when it passes through the capillary and could lead to plasma leakage between the cell surface and the capillary wall. In this study, a rectangular channel was introduced, the side walls of which were moderately constricted, as a representative of axially asymmetric capillaries. Dependence of transit time of a neutrophil passing through the constriction on the constriction geometry, i.e., channel height, throat width and curvature radius of the constriction, was numerically investigated, the transit time being compared with that through the axisymmetric model. It was found that the transit time is dominated by the throat hydraulic diameter and curvature radius of the constriction and that the throat aspect ratio little affects the transit time with a certain limitation, indicating that if an appropriate curvature radius is chosen, such a rectangular channel model can be substituted for an axisymmetric capillary model having the same throat hydraulic diameter in terms of the transit time by choosing an appropriate curvature radius. Thus, microchannels fabricated by the photolithography technique, whose cross section is generally rectangular, are expected to be applicable to in vitro model experiments of neutrophil retention and passage in the alveolar capillaries.