Dependence on exercise intensity of changes in electrolyte secretion from the skin sampled by a simple method

Secreta from the palm and forearm was sampled for 1-min periods by a new technique, using a glass cylinder. Subjects exercised for 10-min periods at successive intensities of 40%, 50% and 65% VO2max with a leg ergometer operated in the supine position. Changes in the concentrations (values) of Na+, K+ and Cl- in their secreta during exercise were investigated. Significant positive correlations were found between the values of any two electrolytes in samples from the palm or the forearm, but the correlations between values for any one of the three electrolytes from the two sites were not significant. Values for concentrations of the electrolytes were significantly higher in samples from the palm than in those from the forearm at rest, 10 min after the beginning of exercise and at the end of exercise. No significant correlation was found between values for electrolytes in samples from the palm and the exercise intensity, but values for Na+ in samples from the forearm increased stepwise with increase in exercise intensity, and similar tendencies were observed for values of K+ and Cl-. The values for the three electrolytes in samples from the forearm, but not the palm, were significantly correlated with values for blood lactate, the percentage of VO2max and the heart rate. These results suggest that the present technique is suitable for successive samplings of secreta from the forearm, and that values for the electrolytes in samples are useful indices of exercise intensity.     

The effect of pulse repetition rate on the delay sensitivity of neurons in the auditory cortex of the FM bat,Myotis lucifugus

1. Echo delay is the primary cue used by echolocating bats to determine target range. During target-directed flight, the repetition rate of pulse emission increases systematically as range decreases. Thus, we examined the delay tuning of 120 neurons in the auditory cortex of the bat, Myotis lucifugus, as repetition rate was varied. 2. Delay sensitivity was exhibited in 77% of the neurons over different ranges of pulse repetition rates (PRRs). Delay tuning typically narrowed and eventually disappeared at higher PRRs. 3. Two major types of delay-sensitive neurons were found: i) delay-tuned neurons (59%) had a single fixed best delay, while ii) tracking neurons (22%) changed their best delay with PRR. 4. PRRs from 1-100/s were represented by the population of delay-sensitive neurons, with the majority of neurons delay-sensitive at PRRs of at least 10-20/s. Thus, delay-dependent neurons in Myotis are most active during the search phase of echolocation. 5. Delay-sensitive neurons that also responded to single sounds were common. At PRRs where delay sensitivity was found, the responses to single sounds were reduced and the responses to pulse-echo pairs at particular delays were greater than the single-sound responses. In facilitated neurons (53%), the maximal delay-dependent response was always larger than the best single-sound responses, whereas in enhanced neurons (47%), these responses were comparable. The presence of neurons that respond maximally to single sounds at one PRR and to pulse-echo pairs with particular echo delays at other PRRs suggests that these neurons perform echo-ranging in conjunction with other biosonar functions during target pursuit.     

Mechanism of the stimulatory effect of cyclodextrins on lankacidin-producing Streptomyces

Summary Gel-filtration analysis of a mixture of cyclodextrin (CyD) and lankacidin C showed that -CyD had strong, -CyD weak and -CyD no affinity for lankacidin C. Lankacidin C production activity, which was assayed by measuring the incorporation of l-[methyl-¹⁴C-]methionine into the lankacidin molecule, was the greatest with cells grown in the presence of -CyD, less with -CyD and the least with -CyD. Lankamycin and T-2636M, which are by-products in lankacidin C fermentation, were not included by -CyD and their production was not stimulated by -CyD. It was apparent that the stimulatory effect of CyD was closely related to the formation of an inclusion complex between CyD and the antibiotic. Lankacidin C biosynthesis was repressed by preincubating cells with lankacidin C, while the repressive effect of lankacidin C was abrogated by the inclusion by -CyD. Thus, abrogation of feed-back repression seems to be a main mechanism of the effect of CyD. However, -CyD, which had no affinity for lankacidin C, stimulated the production to the least extent and exhibited a complementary effect on the stimulation by -CyD or -CyD. -CyD also caused a change in cell morphology and cell-surface hydrophobicity. It was assumed that the modification of the cell surface is a secondary mechanism of the effect of CyD.The second report of the stimulatory effect of cyclodextrins on lankacidin fermentationOffprint requests to: H. Sawada     

Morphology and molecular phylogeny of the marine diatom genus Nagumoea (Bacillariophyceae) from Japan

The canal-bearing diatom genus Nagumoea, described based on only morphological evidence, was tentatively assigned to the order Bacillariales, although its phylogenetic position remained unclear. Because three isolates of Nagumoea (SK002, SK024 and SK053) were successfully established from Japanese coasts, we performed their morphological observations and molecular phylogenetic analyses to discuss the phylogeny and taxonomic position of this genus. Strains SK002 and SK024 were identified as Nagumoea africana, whereas SK053 conformed with Nagumoea serrata. There was high interspecific divergence between N. africana and N. serrata in the rbcL sequences (8.03–8.17%), indicating their distinctness. Furthermore, intraspecific variations were detected within N. africana (2.35%) in the rbcL, implying its cryptic diversity. The maximum likelihood and Bayesian phylogenetic trees inferred from the plastid rbcL, psbC and nuclear 18S rDNA genes recovered Nagumoea as monophyletic with strong statistical support and embedded within an unresolved, poorly supported lineage containing Achnanthes, Craspedostauros, Staurotropis and Undatella in the canal-bearing order Bacillariales (= the family Bacillariaceae). Although the constrained tree based on the monophyly of Nagumoea and the other canal-bearing clade (Surirellales and Rhopalodiales) was statistically rejected by the topology tests, the phylogenetic position of Nagumoea with other Bacillarialean members remains equivocal. The possession of two plastids positioned fore and aft, observed in the present study, and lack of keel, typical of the Bacillariales, indicate the possibility of Nagumoea being part of the ingroup of the Bacillariales or its closely related outgroup.     

Chemical synthesis of insulin-like peptide 1 and its potential role in vitellogenesis of the kuruma prawn Marsupenaeus japonicus

The insulin superfamily comprises a group of peptides with diverse physiological functions and is conserved across the animal kingdom. Insulin-like peptides (ILPs) of crustaceans are classified into four major types: insulin, relaxin, gonadulin, and androgenic gland hormone (AGH)/insulin-like androgenic gland factor (IAG). Of these, the physiological functions of AGH/IAG have been clarified to be the regulation of male sex differentiation, but those of the other types have not been uncovered. In this study, we chemically synthesized Maj-ILP1, an ILP identified in the ovary of the kuruma prawn Marsupenaeus japonicus, using a combination of solid-phase peptide synthesis and regioselective disulfide bond formation reactions. As the circular dichroism spectral pattern of synthetic Maj-ILP1 is typical of other ILPs reported thus far, the synthetic peptide likely possessed the proper conformation. Functional analysis using ex vivo tissue incubation revealed that Maj-ILP1 significantly increased the expression of the yolk protein genes Maj-Vg1 and Maj-Vg2 in the hepatopancreas and Maj-Vg1 in the ovary of adolescent prawns. This is the first report on the synthesis of a crustacean ILP other than IAGs and also shows the positive relationship between the reproductive process and female-dominant ILP.     

Identification of Influenza C Virus Phosphoproteins

The HMV-II cells infected with influenza C virus were labeled with inorganic [³²P]phosphate to identify phosphorylated proteins. Analysis by radioimmunoprecipitation with antiviral serum or monoclonal antibodies revealed that three major structural proteins of the virus, hemagglutinin-esterase (HE), nucleoprotein (NP), and matrix protein (M1) are all phosphorylated in both infected cells and virions. It was also observed that, in the presence of trypsin (10 μg/ml), the unphosphorylated form of the HE glycoprotein was cleaved efficiently whereas the phosphorylated form was not, raising the possibility that phosphorylation of HE may influence its susceptibility to degradation by proteolytic enzymes.     

Effect of 6059-S,a novel oxacephem,on cross-linking reaction of peptidoglycan biosynthesis in Escherichia coli,Pseudomonas aeruginosa and Serratia marcescens

The effect of 6059-S, a novel 1-oxacephem, on peptidoglycan synthesis was investigated using ether-treated cells of Escherichia coli K 12, Pseudomonas aeruginosa KM 338 and Serratia marcescens IFO 12648. The cross-linking reaction of peptidoglycan synthesis in these organisms was inhibited by markedly low concentration of 6059-S.Non-standard abbreviations PBP penicillin binding protein - MIC minimum inhibitory concentration - ETB ether treated bacterial cells - SDS sodium dodecylsulfate     

Molecular cloning of cDNA for the import precursor of human subunit B of H(+)-ATP synthase in mitochondria.

The nucleotide sequence of the import precursor of subunit b of human H(+)-ATP synthase has been determined from a recombinant cDNA clone isolated by screening a human kidney cDNA library with a cDNA for rat subunit b as a probe. The sequence was composed of 1,134 nucleotides including a coding region for the import precursor of subunit b and noncoding regions on the 5'- and 3'-sides. The import precursor of subunit b and its mature polypeptide deduced from the open reading frame were found to consist of 256 and 214 amino acid residues with molecular weights of 28,893 and 24,610, respectively. The presequence of 42 amino acids could be the import signal peptide for directing the protein into the mitochondrial matrix.     

Sucrose-diet feeding induces gene expression of heat shock protein in rat brain under stress

Stress-induced hyperphagia is enhanced in the presence of sweets, particularly sucrose, which may act to attenuate stress. Recently, it was also reported that heat shock protein (HSP) may be involved in the defense against stress. To explore whether sucrose alters gene expression of HSP under stress, we determined the HSP mRNA levels in the hypothalamus, cerebellum, and cerebral cortex after restraint stress in sucrose-diet-fed rats. Competitive RT-PCR revealed that gene expressions of HSP27 in the cerebral cortex and cerebellum and of HSP70 in the cerebral cortex, hypothalamus, and cerebellum were induced by restraint stress under a sucrose-diet-fed condition. However, restraint stress by itself or sucrose diet alone did not induce expression of HSP27 or HSP70 mRNA in any of the three anatomical parts. It is suggested that sucrose facilitates the gene expression of HSP27 and HSP70 in brain after restraint stress, which may attenuate stress.