A preliminary study on quantitative relations among growth,reproduction and mortality in fishes

As a quantitative approach to the life histories of fishes, the present paper attempted to predict a relation among reproduction, growth and mortality numerically with a technique of control theory, the discrete maximum principle. A method for predicting the relation was derived on the postulate that natural selection maximized the net reproductive rate subject to a few constraints. The derived method was applied to Atlantic cod and Atlantic herring populations in the Southern Gulf of St. Lawrence as numerical examples. The examples demonstrated that the theoretical reproductive effort and body weight were well consistent with the observed ones every age but the theoretical survival rates were slightly different from the observed ones. For the reasons mentioned below, however, it should be interpreted that the examples rather support the adopted postulate to a certain degree. First, in general, it is very difficult to obtain good estimates of the rates with traditional methods. Second, intense fishing pressure possibly changes the life history parameters to some extent in fish populations. Moreover, the examples also suggested that, to examine the postulate in further detail, similar analyses had to be made with the data of many fish populations on which intense fishing pressure had not been exerted.     

Interannual fluctuations in recruitment and growth of the sardine,Sardinops melanostictus,in the sea of Japan and adjacent waters

Recruitment and growth of the sardineSardinops melanostictus fluctuated markedly in the Sea of Japan and adjacent waters between 1978 and 1993. Stock size was calculated using Virtual Population Analysis and average body length in each age class was determined by the number of annual rings on the scales. There is an inverse correlation between average water temperature at a depth of 50 m in the coastal area of the mainland of Japan in winter (January to March) and recruitmentR defined as the number of individuals at 1 year old. There is also an inverse correlation between spawning stock sizeE and reproductive success in (R/E). A multiple regression model using spawning stock size and water temperature in winter as independent variables can explain 73% of variance in reproductive success. It suggests that both density-dependent and density-independent factors perform important roles determining reproductive success. There is an inverse correlation between body length and stock size and this suggests that there is a density-dependent effect on the growth of the sardine.     

Kinetics of growth and lactic acid production in continuous and batch culture

Summary In a lactic acid fermentation by Streptococcus faecalis, the specific consumption rate of glucose (v) and the specific production rate of lactic acid () were represented by the following simple equations as functions of the specific growth rate (): 1/=(1/) + 1/ = (1/) + By use of data from a batch culture, these two equations were derived from enzyme kinetics of the product inhibition. These equations were successfully applied to the results of batch culture and chemostat culture. In addition, calculation of ATP yield by these equations agreed with the experimental results better than the conventional Leudeking-Piret type equation, which includes two terms associated with growth and not with growth. Correspondence to: H. Ohara     

Site-specific N-glycosylation of human chorionic gonadotrophin--structural analysis of glycopeptides by one- and two-dimensional 1H NMR spectroscopy.

Glycopeptides representing individual N-glycosylation sites of the heterodimeric glycoprotein hormone human chorionic gonadotrophin (hCG) were obtained from subunits hCG alpha (N-glycosylated at Asn-52 and Asn-78) and hCG beta (N-glycosylated at Asn-13 and Asn-30) by digestion with trypsin and chymotrypsin, respectively. Following purification by reverse-phase HPLC and identification by amino acid sequencing, the glycopeptides were analysed by one- and two-dimensional 1H NMR spectroscopy. The results are summarized as follows: (i) oligosaccharides attached to Asn-52 of hCG alpha comprised monosialylated 'monoantenary' NeuAc alpha 2-3Gal beta 1-4GlcNAc beta 1-2Man alpha 1-3[Man alpha 1-6]Man beta 1-4GlcNAc beta 1-4GlcNAc (N1-4'), disialylated diantennary NeuAc alpha 2-3Gal beta 1-4GlcNAc beta 1-2Man alpha 1-3[NeuAc alpha 2-3-Gal beta 1-4GlcNAc beta 1-2Man alpha 1-6]Man beta 1-4GlcNAc beta 1-4GlcNAc (N2), and the monosialylated hybrid-type structures NeuAc alpha 2-3Gal beta 1-4GlcNAc beta 1-2Man alpha 1-3[Man alpha 1-3Man alpha 1-6]Man beta 1-4GlcNAc beta 1-4GlcNAc (N1-A) and NeuAc alpha 2-3Gal-beta 1-4GlcNAc beta 1-2Man alpha 1-3[Man alpha 1-3(Man alpha 1-6)Man alpha 1-6]Man beta 1-4GlcNAc beta 1-4GlcNAc (N1-AB) in a ratio approaching 5:2:2:1; (ii) Asn-78 of hCG alpha carried N2 and N1-4' almost exclusively (ratio approximately 3:2); (iii) both N-glycosylation sites of hCG beta contained predominantly component N2, partially (approximately 25%) and completely alpha 1-6-fucosylated at the N-acetylglucosamine linked to Asn-13 and Asn-30, respectively. The distinct site-specific distribution of the oligosaccharide structures among individual N-glycosylation sites of hCG appears to reflect primarily the influence of the surrounding protein structure on the substrate accessibility of the Golgi processing enzymes alpha-mannosidase II, GlcNAc transferase II and alpha 1,6-fucosyltransferase.     

Effect of NADP+ on light-induced cytochrome changes in membrane fragments from a blue-green alga

The effect of NADP⁺ on light-induced steady-state redox changes of membrane-bound cytochromes was investigated in membrane fragments prepared from the blue-green algae Nostoc muscorum (Strain 7119) that had high rates of electron transport from water to NADP⁺ and from an artificial electron donor, reduced dichlorophenolindophenol (DCIPH₂) to NADP⁺. The membrane fragments contained very little phycocyanin and had excellent optical properties for spectrophotometric assays. With DCIPH₂ as the electron donor, NADP⁺ had no effect on the light-induced redox changes of cytochromes: with or without NADP⁺, 715- or 664-nm illumination resulted mainly in the oxidation of cytochrome f and of other component(s) which may include a c-type cytochrome with an α peak at 549 nm. With 664 nm illumination and water as the electron donor, NADP⁺ had a pronounced effect on the redox state of cytochromes, causing a shift toward oxidation of a component with a peak at 549 nm (possibly a c-type cytochrome), cytochrome f, and particularly cytochrome b₅₅₉. Cytochrome b₅₅₉ appeared to be a component of the main noncyclic electron transport chain and was photooxidized at physiological temperatures by Photosystem II. This photooxidation was apparent only in the presence of a terminal acceptor (NADP⁺) for the electron flow from water.     

Action of chondroitinases. II. Numerical calculation of the degree of multiple attack.

Further investigation was carried out on the action patterns of two chondroitinase-AC [EC 4.2.2.5.] preparations obtained from Arthrobacter aurescens and Flavobacterium heparinum. To infer the action patterns of the chondroitinases, we proposed a new method for the calculation of the degree of multiple attack, based on the concept established by Robyt and French ((1967) Arch. Biochem. Biophys. 122, 8-16). It was shown that the degree of multiple attack (DM) is represented by the ratio of the initial velocity of number-average degree of scission to that of viscosity-average degree of scission. By this method, DM for A-Chase was estimated to be 3.03 and for F-chase, 1.31.     

A complex interaction between Wnt signaling and TNF-α in nucleus pulposus cells

Introduction

Increased expression of the proinflammatory cytokine TNF-α in intervertebral discs (IVDs) leads to inflammation, which results in progressive IVD degeneration. We have previously reported that activation of Wnt-β-catenin (hereafter called Wnt) signaling suppresses the proliferation of nucleus pulposus cells and induces cell senescence, suggesting that Wnt signaling triggers the process of degeneration of the IVD. However, it is not known whether cross talk between TNF-α and Wnt signaling plays a role in the regulation of nucleus pulposus cells. The goal of the present study was to examine the effect of the interaction between Wnt signaling and the proinflammatory cytokine TNF-α in nucleus pulposus cells.

Methods

Cells isolated from rat nucleus pulposus regions of IVDs were cultured in monolayers, and the expression and promoter activity of Wnt signaling and TNF-α were evaluated. We also examined whether the inhibition of Wnt signaling using cotransfection with Dickkopf (DKK) isoforms and Sclerostin (SOST) could block the effects of pathological TNF-α expression in nucleus pulposus cells.

Results

TNF-α stimulated the expression and promoter activity of Wnt signaling in nucleus pulposus cells. In addition, the activation of Wnt signaling by 6-bromoindirubin-3′-oxime (BIO), which is a selective inhibitor of glycogen synthase kinase 3 (GSK-3) activity that activates Wnt signaling, increased TNF-α expression and promoter activity. Conversely, the suppression of TNF-α promoter activity using a β-catenin small interfering RNA was evident. Moreover, transfection with DKK-3, DKK-4, or SOST, which are inhibitors of Wnt signaling, blocked Wnt signaling-mediated TNF-α activation; these effects were not observed for DKK-1 or DKK-2.

Conclusions

Here, we have demonstrated that Wnt signaling regulates TNF-α and that Wnt signaling and TNF-α form a positive-feedback loop in nucleus pulposus cells. The results of the present study provide in vitro evidence that activation of Wnt signaling upregulates the TNF-α expression and might cause the degeneration of nucleus pulposus cells. We speculate that blocking this pathway might protect nucleus pulposus cells against degeneration.     

Isolation of Aspergillus caninus (Synonym: Phialosimplex caninus) from a Canine Iliac Lymph node

Mycopathologia - Aspergillus caninus (synonym: Phialosimplex caninus) is an anamorphic fungus species associated with systemic infections in dogs that has been transferred from the genus...