Estimation of population fecundity of the bitterling,Rhodeus ocellatus,and ecological significance of its spawning habit into bivalves

Fluctuations of the population abundance of the rose bitterling,Rhodeus ocellatus (Kner) in a small pond, Shimizu-ike (700 m²), Osaka Prefecture, Japan, were estimated by the Petersen method from 1973 to 1977. The number of fish fluctuated between 12,600 and 46,700 during that period. In 1974, a large reproductive peak in May contributed mainly by 2- and 3-year-old spawners and a small peak in late July contributed by 1–2-year-old fish were observed. Average number of eggs laid in a bivalve,Anodonta woodiana Lea, in each month was estimated with field experiments from March to November, 1974. In total, 93,400 eggs were laid during the first reproductive peak, and 13,100 eggs during the second reproductive peak. The mortality of eggs and larvae incubated in the bivalve was less than 30%, and approximately 70 % of the larvae that had swum out from the host died in the following six months. Thus, it is estimated that approximately 20% of the eggs laid in the bivalves can survive and grow up to reach the first maturity. The high survival rate ofR. ocellatus among cyprinid fishes might be due to the fact that the eggs and larvae are protected from predation by being embedded in a bivalve, and to the fact that the larvae at the earliest free swimming stage have a good opportunity of surviving because they are much larger in size and more developed morphologically than those of other cyprinid fishes.     

Similarities between rat liver mitochondrial and cytosolic glutathione reductases and their apoenzyme accumulation in riboflavin deficiency

Glutathione reductase has been purified 5,500-fold from rat liver mitochondrial matrix in a yield of 30%. The mitochondrial enzyme was immunochemically indistinguishable from that of the cytosol and the subunit molecular weight was apparently similar to that of the cytosolic enzyme, that is, 50,000 daltons. The optimum pH and kinetic properties investigated were not significantly different from those of the cytosolic enzyme. When rats were fed a riboflavin-deficient diet, the enzyme activity in the mitochondria decreased to a greater extent than that in the cytosol, and greater accumulation of apo-enzyme in the former than that in the latter was confirmed by the amount of immunoprecipitable protein, activation by FAD addition in vitro, and the enzyme activity recovery after injection of riboflavin, into riboflavin-deficient rats.     

Variation in the ribosomal RNA genes among individuals of Vicia faba

Summary Length heterogeneity in the ribosomal repeat of Vicia faba is due to the presence of variable numbers of a 325 bp subrepetitive element within the nontranscribed spacer region. The distribution of size classes among 88 individuals within a population was investigated by blot-hybridization. We find that individual plants can exhibit more than 20 size classes and that hybridization patterns are highly diverse from individual to individual, more so than for any species so far investigated. In contrast, no such differences are observed in patterns for different tissues from a single plant or from parental to F₁ generation. Some changes were observed in the F₂ generation. We conclude that unequal recombination can give rise to the diversity that we observe for the V. faba rDNA repeats.     

A single amino acid substitution in the A subunit of Escherichia coli enterotoxin results in a loss of its toxic activity

A plasmid encoding a mutant gene of heat-labile enterotoxin (LT), produced by enterotoxigenic Escherichia coli, was induced by treatment of plasmid EWD 299 with hydroxylamine. A mutant strain of E. coli HB 101 carrying the mutant plasmid pTUH 6A produced a low toxic LT analogue (mutant LT), which was cross-reactive with anti-LT antibody. The mutant LT activity was less than 0.15 and 0.006% of the normal LT in the rabbit ileal loop test and in the rabbit skin permeability test, respectively. The amino acid composition of the mutant LT-B subunit was the same as that of the normal B subunit. Though the A2 fragment of the mutant LT was identical to normal LT by DNA analysis, the A1 fragment of the mutant LT differed from the normal A1 fragment in one amino acid at position 112; namely it had lysine instead of glutamic acid from the N terminus. These data suggest that glutamic acid at position 112 from the N terminus of the A1 fragment is important for the A subunit to express its biological activity.     

Quantitative analysis of serum IL-6 and its correlation with increased levels of serum IL-2R in HIV-induced diseases

We have devised a luminescence sandwich ELISA for the quantification of IL-6 in both sera and cell culture supernatants, which had a detection limit of 100 fg/ml of test sample. By using the luminescence sandwich-ELISA, low but measurable levels of IL-6 (9.5 pg/ml on average) were found in the sera from normal individuals. The serum levels of IL-6 were elevated in HIV-seropositive asymptomatic carriers (55.5 pg/ml on average), and the IL-6 levels were correlated with the degree of HIV-induced disease progression (AIDS-related complex 106.8 pg/ml on average and (AIDS 283 pg/ml). IL-6 immunoreactivity in the sera of AIDS patients eluted at a 25,000 m.w. major peak, which was biologically active and heat-stable, and a 500,000 m.w. minor peak in size-exclusion HPLC. Interestingly, a significant correlation was observed between the serum IL-6 levels and soluble IL-2R levels. In vitro, HIV infection of PHA-activated PBMC led to enhanced release of IL-6 into the culture supernatants. Moreover, soluble IL-2R release was markedly increased by adding exogenous IL-6, whereas it was decreased by adding the neutralizing anti-IL-6 mAb to the cultures. These results demonstrate that increased IL-6 levels are significantly associated with sIL-2R levels, and suggest a cause of the increased levels of this receptor in patients with HIV infection. Furthermore, both serum IL-6 and serum IL-2R levels in HIV infection reflect the stage of the HIV-induced disease.     

Induction of cyclo-oxygenase synthesis in human promyelocytic leukaemia (HL-60) cells during monocytic or granulocytic differentiation.

Cyclo-oxygenase (COX) production in human promyelocytic leukaemia (HL-60) cells was studied during monocytic differentiation induced by 1 alpha, 25-dihydroxyvitamin D3 (24 nM; 3 days) or phorbol 12-myristate 13-acetate (100 nM; 1 day), or during granulocytic differentiation induced by retinoic acid (1 microns; 4 days). Undifferentiated or differentiated HL-60 cells were labelled with [35S]methionine, and membrane-bound COX was solubilized and quantified by SDS/PAGE. Immunoprecipitated 35S-labelled COX from cells induced to differentiate into monocytic or granulocytic lineage were clearly detected on the autoradiograms as a protein of approx. 70 kDa molecular size, whereas only a very faint COX band was detected in untreated HL-60 cells. During both monocytic and granulocytic differentiation, COX activity (measured by the conversion of exogenous arachidonic acid into prostaglandin E2) was dramatically increased. In addition, thromboxane synthesis was preferentially enhanced during monocytic differentiation. HL-60 cells, induced to differentiate into the monocytic or granulocytic lineage, provide a useful tool to investigate the cellular mechanisms involved in regulation of the synthesis of individual prostanoid-metabolizing enzymes.     

Communicative interaction of myosins along an actin filament in the presence of ATP

Myosin molecules contacting an actin filament in the presence of ATP were found to regulate the filamental fluctuations due to ATP hydrolysis in a communicative manner along the filament. As an evidence of the occurrence of the communication, ATP-activated fluctuating displacements of the filament in the direction perpendicular to its longitudinal axis were identified to propagate at a finite velocity not less than about 0.2 μm/s unidirectionally along the filament.     

The CLS2 gene encodes a protein with multiple membrane-spanning domains that is important Ca2+ tolerance in yeast

Genetic screening of Saccharomyces cerevisiae mutants defective in Ca²⁺ homeostasis identified cls2, which exhibits a specific Ca²⁺-sensitive growth phenotype. We describe here the CLS2 gene and a multicopy suppressor (named BCL21, for bypass of CLS2) of the cls2 mutation. The CLS2 gene encodes a polypeptide of 410 amino acid residues, and its hydropathy profile indicates that the predicted Cls2 protein (Cls2p) contains ten putative membrane spanning regions. Immunofluorescent staining of the yeast cells expressing epitopetagged Cls2p suggests that Cls2p is localized to endoplasmatic reticulum (ER) membrane. A cls2 disruption strain is viable, but shows a Ca²⁺-sensitive phenotype like the original cls2 mutants. BCL21 suppresses the cls2 disruption mutation, indicating that the multicopy suppression does not require the Cls2p. Suppression of cls2 was observed even after introduction of a singlecopy plasmid harboring BCL21. The BCL21 gene encodes a protein of 382 amino acid residues and is identical to the SUR1 gene. sur1 was originally isolated as a suppressor of rvs161, which has reduced viability in nutrient starvation conditions. Possible mechanisms of the multicopy suppression are discussed.