Inter-twin relationships and mental health.

We evaluated dominance-submissiveness between co-twins and its relationship to mental health in a cohort study of 419 twins followed from pregnancy to 22-30 years of age. Dominance-submissiveness between co-twins was assessed from three separate perspectives: physical dominance, psychological dominance, and verbal dominance. Depressive, nervous, and psychosomatic symptoms were analyzed in different twin groups. In the physical domain, males were more commonly dominant than females at school age and in adulthood. Before and at school age, girls were more dominant than boys in the psychological and verbal domains, as well as in total dominance. These differences disappeared in adulthood, and 81% of adult twins felt themselves equal to their co-twin in total dominance. Submissiveness in the psychological domain seemed to be associated with increased depressiveness, nervous complaints and psychosomatic symptoms in males of male-female twin pairs. Verbally submissive males in same-sex twin pairs had more depression and psychosomatic symptoms. Among females of same-sex twin pairs, submissiveness in the psychological domain was most clearly associated with depressive symptoms, whereas psychological or verbal dominance-submissiveness among females from male-female twin pairs was not associated with symptoms. Psychologically dominant males and females of same-sex twin pairs expressed greater nervousness than did their co-twins. We conclude that being submissive, especially in the psychological domain, to a female twin partner seems to be stressful, whereas it is easier, especially for females, to be submissive to a male twin partner.     

Adenylate cyclase activity of membrane fractions isolated from sea urchin sperm

The adenylate cyclase activity of sperm membrane fragments isolated from Lytechinus pictus sperm according to Cross [20] has been studied. Two distinct fractions preferentially coming from the flagellar plasma membrane are obtained. Surface I¹²⁵-labeling experiments performed by Cross [20] indicate that these membranes are representative of the entire sperm plasma membrane. Both fractions are enriched in their adenylate cyclase activity: the specific activity of the top membranes is eightfold higher than in whole sperm, whereas that of the middle membranes is 15-fold higher. The cyclase seems to be associated with the membranes. Lytechinus pictus egg jelly has no effect or slightly inhibits the adenylate cyclase activity of the isolated sperm plasma membrane fragments. Mg⁺⁺ and Na⁺ stimulated their cyclase activity about sevenfold at 2.5 mM Mn⁺⁺ and 3.2 mM ATP. At this ATP to Mn⁺⁺ ratio, high concentrations of Ca⁺⁺ have a small stimulatory effect.     

Modulation of deoxyribonucleic acid polymerase III level during the life cycle of Bacillus subtilis.

Deoxyribonucleic acid (DNA) polymerase III is not detectable in Bacillus subtilis spores; the enzyme activity appears 20 to 30 min after spore activation and rapidly increases just before the onset of the first round of DNA replication (30 min later); the level of polymerase III further increases and reaches its maximum (on a per-genome basis) when the cells enter the vegetative phase of growth; this level is six- to eightfold higher than the one observed during germination. In the stationary phase, the polymerase III drops to levels comparable to those found in germinating spores at the first round of replication. On the contrary, DNA polymerase I is present at appreciable levels in the dormant spore; it increases during vegetative growth by a factor of three and, during the stationary phase, reaches its maximum level which is sixfold higher than that observed in the spores. The block of protein synthesis during vegetative growth does not cause an appreciable reduction of the two enzymes (in absolute terms), showing that the regulation of their levels is probably not due to a balance between synthesis and breakdown. These results indicate that polymerase III is probably one of the factors controlling the initiation of DNA synthesis during spore germination.     

Isethionate and taurine transport sites at brain cell membranes: Influx studies with brain slices

The influx of [¹⁴C]isethionate (ISA) into rat brain slices was studied with and without taurine. This influx was relatively rapid, but took place largely by a non-saturable, passive mechanism, which transferred much less ISA into the brain cells than taurine. Taurine inhibited the influx of ISA competitively (K _m=50 and 100 mol/l) at low ISA concentrations, and ISA that of taurine non-competitively (V=200 and 400–700 mol×min^–1×kg^–1 wet weight) at high taurine concentrations. It thus appears that ISA and taurine may have a small number of common transport sites at brain cell membranes, but these are apparently of little significance for the total transport of ISA.     

Bacillus subtilis deoxyribonuclease activity specific for single-stranded deoxyribonucleic acid: cellular site and variations during germination and sporulation

The endonuclease of Bacillus subtilis specific for single-stranded deoxyribonucleic acid is absent in spores, appears during germination only after the start of deoxyribonucleic acid synthesis, and is located almost exclusively in the periplasm.     

On the identity of dnaP and dnaF genes of Bacillus subtilis

Summary The dnaP strains of Bacillus subtilis are altered in the initiation of DNA replication at high temperature (Riva et al., 1975). Fine mapping of the gene shows that it is located very close to the dnaF gene, described by Karamata and Gross (1970) and mapped by Love et al. (1976) in the polC region. The phenotype of both mutants is indistinguishable: the DNA synthesis stops at non permissive temperature after synthesizing an amount of DNA equivalent to the completion of the rounds of replication already initiated; at permissive temperature they are abnormally sensitive to MMS and are reduced in the ability to be transformed. Both mutants are to be considered as belonging to the dnaF locus.The dnaF gene is very close to the polC gene, which specifies the DNA polymerase III of B. subtilis. The DNA polymerase III of the dnaF mutants is not temperature sensitive in vitro, however, the level of this enzyme is lower by a factor of 4 or 5 in the dnaF mutants, at the permissive temperature. Following shift of dnaF cultures to the non permissive temperature, the level of DNA polymerase III activity specifically decreases further by a factor of at least 10 in the mutant, whereas the DNA polymerase I level is unaffected.The possible roles of the dnaF gene in the control of the cellular level of the DNA polymerase III, and the possibility of a regulatory role of DNA polymerase III in the initiation of DNA replication in bacteria are discussed.Abbreviations and symbols HPUra 6-(p-hydroxyphenylazo)-uracil; mic, minimum inhibitory concentration - MMS methyl-methanesufonate - Pol I Pol II and Pol III: DNA polymerase I, II and III respectively - PCMB parachloro-mercuri-benzoate     

A simplified procedure for the analysis of DNA polymerase III levels in Bacillus subtilis strains.

A simple and reproducible procedure is described which allows the fast and almost quantitative removal of DNA polymerases I and II from DNA polymerase III, in crude extracts of polA+ strains of Bacillus subtilis. The procedure entails streptomycin sulfate and ammonium sulfate fractionations; subsequent analysis of the partially purified preparation by G-200 chromatography, DEAE cellulose chromatography and density gradient sedimentation, shows that the ammonium sulfate fraction contains less than 5% of the total activity as DNA polymerase I and less than 2% as DNA polymerase II. The purification procedure, up to the ammonium sulfate step, was utilized for the analysis of the level of DNA polymerase III in several B. subtilis mutants, with results comparable to those obtained from the corresponding polA- strains following more cumbersome purification procedures. The M.W. of the purified form is of 227.000, somewhat greater than the published values. The early fractions of the purification have revealed the existence of a form with a M.W. of 426.000; the nature of this form, which has been observed in several instances and which is very unstable and short-lived, is under investigation.