Effects of physical exercise on the elasticity and elastic components of the rat aorta

To evaluate the effects of exercise on aortic wall elasticity and elastic components, young male rats underwent various exercise regimes for 16 weeks. In the exercised rats, the aortic incremental elastic modulus decreased significantly when under physiological strain. The aortic content of elastin increased significantly and the calcium content of elastin decreased significantly in the exercised group. The accumulated data from the exercised and sedentary groups revealed that the elastin calcium content was related positively to the incremental elastic modulus. We concluded that physical exercise from an early age decreases the calcium deposit in aortic wall elastin and that this effect probably produced in the exercised rats a distensible aorta.     

Simultaneous determination of nitrazepam and its metabolites in urine by micellar electrokinetic capillary chromatography

We applied micellar electrokinetic capillary chromatography to simultaneous separation and determination of nitrazepam and its major metabolites, 7-aminonitrazepam and 7-acetamidonitrazepam, in spiked urine. Prior to electrophoresis, the three compounds were successfully extracted from the spiked urine with commercial disposable solid-phase cartridges. The optimum running buffer for the separation was prepared by combining 85 parts of 60 mM sodium dodecyl sulphate—6 mM phosphate—borate, adjusted to pH 8.5, with 15 parts of methanol. The separation order, completed within 25 min, was 7-aminonitrazepam > 7-acetamidonitrazepam > nitrazepam, at an applied potential of 20 kV. We obtained reproducible electropherograms in successive repetitions, and few other peaks or interferences appeared in the electropherogram. The detection limits of the three compounds were 50–100 pg (0.1–0.2 μg/ml of analyte in spiked urine), and the recoveries were 78.9–100.8% for 1 μg/ml and 84.1–100.3% for 5 μg/ml. The application of this method to forensic or clinical samples is demonstrated.     

Host plant conspicuousness and the distribution of eggs and larvae in the butterfly,Anthocharis scolymus (Lepidoptera: Pieridae)

We investigated how the distribution pattern of eggs and larval on the host plant, Turritus glabra, was influenced by the oviposition behavior of the pierid butterfly Anthocharis scolymus. Females searched for the host plants visually and they frequently approached taller host plants with sparse surrounding vegetation. After encountering host plants, oviposition behavior of females was independent of host plant characteristics such as height, density, and type of surrounding vegetation. A female laid eggs singly on a host plants. Most females appeared to lay their eggs regardless of the presense of eggs on the host plant. Consequently egg and larva tended to be abundant on conspicuous host plants as measured by height or relative isolation from other plants. However, overcrowding of eggs on an individual host decreased the survival rate of larvae.     

A Parvalbumin-Like Calcium-Binding Protein Is Present in Plant Leaves

A protein with relatively high homology in its N-terminal aminoacid sequence to animal parvalbumin and oncomodulin has beenidentified in leaves of rice (Oryza sativa L.). The PV-likeprotein has a relative molecular mass of 27,000 and an isoelectricpoint of 5.0. This protein was partially purified by ion-exchangechromatography, and the purified protein was found to have Ca²⁺-bindingactivity in a microscale Ca²⁺-binding assay. Furthermore, anantiserum raised against a synthetic oligopeptide based on theN-terminal amino acid sequence of this protein cross-reactedwith protein not only from rice but also from other monocotyledonousplants. (Received October 17, 1990; Accepted October 17, 1991)     

Control of trophoblast cell differentiation: Lessons from the genetics of early pregnancy loss and trophoblast neoplasia

Trophoblast cell differentiation is crucial to the morphogenesis of the placenta and thus the establishment of pregnancy and the growth and development of the embryo/fetus. In the present review, we discuss current evidence for the existence of regulatory genes crucial to trophoblast cell differentiation and placental morphogenesis. The elucidation of regulatory pathways controlling normal differentiation of trophoblast cells will facilitate the identification of sensitive junctures in the regulatory pathways leading to various developmental disorders, including those associated with the initiation of pregnancy, fetal growth retardation and gestational trophoblast disease.     

Platelet talin is phosphorylated by calyculin A

Calyculin A and okadaic acid, potent and cell permeable inhibitors of type 1 and type 2A protein phosphatases, inhibit platelet aggregation and secretion. However, the relationship between phosphatase inhibition and inhibition of platelet function is not well understood. We found that in unstimulated platelets, talin (P235) was phosphorylated at threonine residues by calyculin A. Furthermore, the extent of talin phosphorylation by calyculin A was closely correlated with its inhibition of thrombin-induced platelet aggregation. Since the binding of talin to platelet glycoprotein IIb/IIIa complex has been shown to be affected by its phosphorylation, these results suggest that type 1 and/or type 2A protein phosphatases may play a role in the regulation of membrane-cytoskeleton interaction through dephosphorylation of talin.     

An electroblotting apparatus for multiple replica technique and identification of human serum proteins on micro two-dimensional gels

A new apparatus for electrophoretic transfer of proteins from micro polyacrylamide slab gels has been developed. The apparatus enabled the easy changing of nitrocellulose sheets and was suited for obtaining multiple blots from a gel. Electrophoretic conditions were determined so that all of the blots obtained sequentially from one slab gel were successfully used to visualize specific proteins irrespective of their molecular weight. Combining the transfer technique with the technique of parallel micro two-dimensional electrophoresis, 20 blots could be obtained within 1 h of electroblotting time. The locations of 28 human serum proteins were determined simultaneously on these blots using commercial specific antisera.     

Purification of chicken gizzard myosin light-chain kinase, and its calcium and strontium sensitivities as compared with those of superprecipitation and ATPase activities of actomyosin

1. A purified preparation of myosin light-chain kinase (MLCK) was obtained from chicken gizzard, and it was shown to consist of two subunits; 130,000 (130 K)-dalton subunit and 17,000 (17 K)-dalton subunit. In amino acid composition the 130 K and 17 K subunits were identical with the 105 K and 17 K subunits of Dabrowska et al. (1977 and 1978), respectively. In disc gel electrophoresis, the 17 K subunit of our MLCK preparation responded to Ca2+ ions in the same way as bovine calmodulin, and differently from skeletal troponin C. There appeared to be one minor difference between 17 K subunit and calmodulin in the primary structure of the C-terminal region. 2. The Ca2+ and Sr2+ concentrations required for the three activities (ATPase and superprecipitation activities and MLCK activity) were measured. Two types of "reconstituted" myosin B were used; one contained 17 K subunit of gizzard MLCK and the other contained bovine brain calmodulin. The two types of "reconstituted" myosin B were practically identical with "natural" myosin B in the Ca2+ and Sr2+ requirements for the three activities measured above. 3. Both the extent and the activity of superprecipitation, and both the limited and steady activities of ATPase were measured. The MLCK activity was estimated in two ways; by urea gel electrophoresis and by measuring 32 P incorporation from [gamma-32P]ATP into myosin. The results thus obtained favor the kinase-phosphatase mechanism of calcium regulation of gizzard muscle contraction.     

Detection of the changes in protein distribution of rat plasma induced by carbon tetrachloride administration by means of two-dimensional electrophoresis

The changes in rat plasma protein distribution after carbon tetrachloride administration were examined using two-dimensional electrophoresis, utilizing isoelectric focusing in polyacrylamide gel in the first dimension and pore gradient polyacrylamide gel electrophoresis in the second dimension. Drastic changes in amount of protein were observed at more than 20 spot positions including those of transferrin, Gc-globulin and low-density lipoprotein. The time course of the changes was examined, and the most drastic changes were observed at 2 days after carbon tetrachloride administration.     

Increase in potential activities of protein phosphatases PP1 and PP2A in lymphoid tissues of autoimmune MRL/MpJ-lpr/lpr mice.

The differential assay conditions for protein phosphatases PP1, PP2A, and PP2C were extensively studied by using crude extracts from mouse lymphoid tissues as enzyme sources. Under these conditions, the protein phosphatase activities were measured in MRL/MpJ-lpr/lpr mice (MRL/lpr mice), autoimmune-prone mice, and MRL/MpJ(-)+/+ mice (MRL/+/+ mice) and C3H/HeJ mice as the controls. In MRL/lpr mice, significant alterations in protein phosphatase activities from those in the control mice were demonstrated. In spleen and liver from MRL/lpr mice, potential activities of PP1 and PP2A were distinctly elevated over those of the control mice. These elevations appeared to be due to accumulation of the abnormal lymphocytes that emerged in MRL/lpr mice. Although the PP1 activity in MRL/lpr lymph nodes was lower than those of normal spleen and thymus, it was greatly increased by Co(2+)-trypsin treatment so that the PP1 activity of MRL/lpr lymph nodes was the highest among those of all the tissues examined. In contrast, PP2C activity showed no remarkable alteration in the autoimmune disease model mice as compared with that in the control mice. These results demonstrated a specific elevation in potency of protein dephosphorylation in the tissues of MRL/lpr mice, suggesting a new explanation for the defect in signal transduction in this disease.