Metabolism of lipid and carbohydrate in sea urchin spermatozoa

When the dry sperm of the sea urchin, Hemicentrotus pulcherrimus, were diluted 100 times in artificial sea water at 0°C and at 20°C, they became motile and the levels of ATP and creatine phosphate decreased rapidly. The level of ADP hardly changed, and the AMP level increased after the dilution. After the dilution, the respiratory rate at 2°C was almost one fifth that of 20°C. Both phospholipid and glycogen were used for the energy sources in sea urchin sperm. The level of phospholipid was 10-fold higher than that of glycogen in the dry sperm. The phospholipid level decreased after dilution at 20°C, though the level hardly changed at 0°C, suggesting that phospholipid was hardly metabolized the lower temperature. The level of α -glycerophosphate increased at 20°C after the dilution but did not change at 0°C. The level of glycogen decreased after the dilution, regardless of the temperature. The glycolysis was also activated after the dilution. Of the intermediates of the tricarboxylic acid cycle, the citrate concentration increased at 0°C and the malate concentration also increased at 0°C and especially strongly at 20°C.     

Utility and efficiency of linked marker genes for genetic counseling. II. Identification of linkage phase by offspring phenotypes

For a linked marker locus to be useful for genetic counseling, the counselee must be heterozygous for both disease and marker loci and his or her linkage phase must be known. It is shown that when the phenotypes of the counselee's previous children for the disease and marker loci are known, the linkage phase can often be inferred with a high probability, and thus it is possible to conduct genetic counseling. To evaluate the utility of linked marker genes for genetic counseling, the accuracy of prediction of the risk for a prospective child with a given marker gene to develop the genetic disease and the proportion of families in which a particular marker locus can be used for genetic counseling are studied for X-linked recessive, autosomal dominant, and autosomal recessive diseases. In the case of X-linked genetic diseases, information from children is very useful for determining the linkage phase of the counselee and predicting the genetic disease. In the case of autosomal dominant diseases, not all children are informative, but if the number of children is large, the phenotypes of children are often more informative than the information from grandparents. In the case of autosomal recessive diseases, information from grandparents is usually useless, since they show a normal phenotype for the disease locus. If we use information on the phenotypes of children, however, the linkage phase of the counselee and the risk of a prospective child can be inferred with a high probability. The proportion of informative families depends on the dominance relationship and frequencies of marker alleles, and the number of children. In general, codominant markers are more useful than are dominant markers, and a locus with high heterozygosity is more useful than is a locus with low heterozygosity.     

Actin polymerization promoted by a heptapeptide, an analog of the actin-binding S site on myosin head

Polymerization of G-actin to F-actin was indicated by an increase in light-scattering intensity after the addition of a heptapeptide (Ile-Arg-Ile-Cys(MT)-Arg-Lys-Gly-OEt), an analog of the actin-binding S-site on S-1 heavy chain. The half-maximal concentration of the heptapeptide which induced an increase in the light-scattering intensity at 25 degrees C was about 110 microM, which was in the range of the dissociation constant of this peptide with F-actin. The polymerization of G-actin to F-actin by binding of the heptapeptide was further demonstrated by ultracentrifugal separation, Pi liberation, and electron microscopy. The polymerization of G-actin was induced only by the heptapeptide, but not by fragments of the heptapeptide. The well known acceleration of polymerization of G-actin by the myosin head may be due to the binding of G-actin with the S-site on the myosin head.     

A Waldenstr?m's macroglobulin with anti-G3m(b1) antibody activity.

A human monoclonal macroglobulin (IgM, K) from a patient (KI) with Waldenstr?m's macroglobulinemia was shown to have antibody activity against a human IgG (Gm) allotype. In hemagglutination tests, only one anti-D serum with G3m(b0b1) reacted with macroglobulin KI. Antiglobulin specificity of macroglobulin KI was determined to be an anti-G3m(b1) antibody by hemagglutination inhibition tests. Fab fragments from macroglobulin KI could react with human IgG3 protein possessing G3m(b1), but Fc fragments could not react. Gm phenotype in IgG isolated from serum KI was determined to be Gm(a,z,g,b0,s,t,u). This is the first report of a Waldenstr?m's macroglobulin with antiglobulin specificity against a Gm allotype.     

Similarity and difference in the mechanisms of neonatally induced tolerance and cyclophosphamide-induced tolerance in mice

The mechanisms of cyclophosphamide (CP)-induced tolerance were investigated by comparing with those of neonatally induced tolerance. When C3H/He Slc (C3H; H-2k, Mls-1b) mice were given i.v. either AKR/J Sea (AKR; H-2k, Mls-1a) or (AKR x C3H)F1 (AKC3F1; H-2k, Mls-1a/b) spleen cells and treated i.p. with CP 2 days later, a long-lasting skin allograft tolerance to AKR was induced in each case without any signs of graft-vs-host disease (GVHD). However, typical signs of GVHD were observed in the C3H mice neonatally tolerized with AKR spleen cells, but not in those tolerized with AKC3F1 spleen cells. The expression of TCR V beta 6, which is strongly correlated with the reactivity to Mls-1a Ag (of donor AKR origin), in the periphery was quite different between the two types of tolerant C3H mice. Namely, in the lymph nodes of the C3H mice tolerized with AKR spleen cells and CP, only CD4(+)-V beta 6+, but not CD8(+)-V beta 6+, T cells selectively disappeared, whereas both of them were abrogated in the lymph nodes of the C3H mice neonatally tolerized of AKR. By contrast, in the thymus of the two types of tolerant C3H mice, both CD4+CD8- and CD4-CD8+ single-positive thymocytes expressing TCR V beta 6 were clonally deleted, suggesting that the thymic involvement was the same in each type of tolerance. These results suggest that the preferential disappearance of the CD4(+)-V beta 6+ T cells (of host origin) and the effector T cells of GVHD (of donor origin) occurred only in the periphery of the C3H mice tolerized with AKR spleen cells plus CP and was attributable to the destruction of Ag-stimulated T cells by the CP treatment. In contrast, the intrathymic clonal deletion of immature V beta 6+ T cells was a common mechanism for both of the tolerance induction systems.     

Expression of retinoic acid receptor genes in neural crest-derived cells during mouse facial development

Retinoic acid (RA) is known as a teratogen that induces abnormalities in facial structures which are made up mainly of neural crest-derived mesenchyme. We investigated expression patterns of RA receptor (RAR) genes (subtypes alpha, beta, gamma) during mouse facial development. The expression of the RAR beta gene is specific for the mesenchyme around developing eyes and nose, whereas the RAR gamma gene is expressed in the mesenchyme differentiating to facial cartilages and bones. In contrast, the RAR alpha gene is expressed weakly and uniformly over the facial region. These results suggest that crucial roles of endogenous RA in facial development depend on differential functions of the RAR subtypes.     

Interleukin-4 as a potent inhibitor of bone resorption

A possible role of interleukin-4 (IL-4) in the regulation of bone turnover was assessed by employing a 45Ca prelabeled-fetal mouse long bone culture system. IL-4 inhibited the bone resorption stimulated by parathyroid hormone (PTH), PTH related protein (PTHrP), 1 alpha, 25, dihydroxy-vitamin D3 [1 alpha, 25 (OH)2 D3], interleukin-1 alpha and - 1 beta (IL-1 alpha, IL-1 beta) and prostaglandin E2 (PGE2). Anti-IL-4 on monoclonal antibody abolished the inhibitory effect of IL-4 on the bone resorption. These results suggest that IL-4 may play an important role on the inhibitory regulation of bone resorption.     

Activin A stimulates meiotic maturation of the rat oocyte in vitro

The effect of activin A on meiotic maturation was analyzed in oocytes from immature rats treated with PMSG. Activin A, which was purified as the erythroid differentiation factor, accelerated the maturation of not only follicle-enclosed oocytes and oocyte-cumulus complexes, but also denuded oocytes, as measured by an increase in the percentage of oocytes with germinal vesicle breakdown (GVBD). Oocyte maturation was not accelerated by activin A in the presence of the inhibitor of GVBD such as cyclic-AMP. These results showed activin A is a potent in vitro stimulator of oocyte maturation.     

The selective inhibition of hippocampal glutamic acid decarboxylase in zinc-induced epileptic seizures

The intracerebroventricular administration of Zn²⁺ (0.3 mol/10 l) causes epileptic seizures characterized by running fits, jumping, vocalization, fasiculation of facial muscles, myoclonic movements of the limbs and tonic-clonic convulsions. These episodes are blocked or reversed by -aminobutyric acid (0.4 mol/10 l). When assayed under conditions where pyridoxal phosphate was not added, the activity of glutamic acid decarboxylase decreased significantly in hippocampus from 18.9 to 15.3 and 9.7 mol¹⁴CO₂ formed/gram proteins/20 min, 15 and 30 min following administration of Zn²⁺. The inhibition of glutamic acid decarboxylase by Zn²⁺ was selective occurring only in hippocampus and not in the hypothalamus, amygdala, caudate or thalamus. The inhibition of glutamic acid decarboxylase was not due to a reduction in the concentration of endogenous pyridoxal phosphate which remained unaltered in hippocampus following Zn²⁺ administration.