Children and marital satisfaction in a non-Western sample: having more children increases marital satisfaction among the Igbo people of Nigeria

Previous research has demonstrated that having more children decreases marital satisfaction among parents. However, the universality of these findings is limited since the vast majority of the studies have been conducted in Western countries. In the present study, 374 people from the Igbo ethnic group (Nigeria) were assessed for levels of marital satisfaction and the number of children. In contrast to almost all previous findings, we found a positive relationship between the number of children and marital satisfaction among parents. Number of children was the strongest predictor of marital satisfaction even when compared to other variables like wealth and education. Our results suggest that the negative relationship between the number of children and marital satisfaction is not culturally universal and probably only characterizes developed, individualistic Western countries. We discuss our findings from a sociocultural and evolutionary perspective.     

Involvement of voltage-dependent calcium channels (VDCC) in the action of GnRH on GtH release in common carp (Cyprinus carpio L): comparison with K+ action.

The involvement of different types of voltage-dependent calcium channels (VDCC) in the stimulatory action of GnRH (in comparison with K+) on maturational gonadotropin (GtH) release was investigated using superfused carp pituitary cells. The action of these 2 stimulants was not modified either by D600 or nifedipine (drugs blocking L-type of VDCC). Cadmium (Cd2+), which blocks all types of VDCC indifferently, provoked a dose-dependent stimulation of GtH secretion. Cd2+ action was not altered by addition of sGnRH in any of the doses. Similar results were obtained using K+ as a secretagogue, but only the highest dose of Cd2+ (200 mumol/l) was able to completely block K+ action. Low doses (0.1 and 1 mumol/l) of the L-type VDCC activator BAY-K8644 did not change basal GtH secretion and had no effect on sGnRH-stimulated GtH secretion. Surprisingly, doses (10 mumol/l and higher) of BAY-K8644 evoked dose-dependent inhibition of GtH secretion. On the other hand, a higher concentration (20 mumol/l) of nifedipine provoked a stimulation of GtH release. Our results indicate that the stimulatory action of GnRH and K+ involves activation of a certain type of cadmium-sensitive VDCC (probably T- or N-type VDCC) whereas dihydropyridine and diphenylalkylamine sensitive VDCC (L-type VDCC) does not participate in this phenomenon. The inhibitory action of BAY-K8644 and, on the other hand, the stimulatory action of nifedipine indicate that L-type VDCC probably play a role in other physiological pathways regulating GtH release in carp.     

Circadian rhythms in Neurospora crassa: the effects of point mutations on the proteolipid portion of the mitochondrial ATP synthetase

Summary Five oligomycin-resistant (oli ^r) mutant strains of Neurospora crassa were analyzed for their growth rate and for the periodicity of their circadian rhythm. The most resistant strains had periods of 18–19 h while the least resistant strain had a normal period of 21.0 h. There was a rough correlation between the in vivo degree of oligomycinresistance and the amount of change in the period. Several of the oli ^r mutations have been previously described by Sebald et al. (1977) in terms of known amino acid changes in the primary structure of the proteolipid, or DCCD-binding protein, found in the F₀ membrane portion of the mitochondrial ATP synthetase. Amino acid changes in the structure of this protein are reported here for two other oli ^r mutations. The proteolipid isolation procedures were slightly modified to include a delipidation step, and an HPLC procedure was developed to separate the hydrophobic peptides of this protein. Analysis of heterocaryons carrying both the oli ^r and oli ^s markers indicated that the oli ^r and oli ^s mutations were codominant to each other in terms of period and growth rate. The changes in the primary structure of this DCCD-binding protein reported here are the first known examples of changes in the primary structure of a protein which alter the period of a circadian rhythm.     

The fate of newly made DNA in Escherichia coli mutants thermosensitive in DNA synthesis

Summary E. coli mutants exist in which DNA synthesis is thermosensitive. In one class of these mutants DNA synthesis stops immediately if a critical temperature (42°C) is reached. When DNA replication in such mutants is followed by ³H thymidine incorporation at 33°C, it is found that 1. only the newly made DNA is degraded at 42°C, 2. the discontinuously replicated DNA is lost predominantly at 42°C, 3. 1–3% of the chromosomal DNA is rendered acid soluble at 42°C without concomitant loss of viability of the cells at 33°C.Replication of phage DNA is inhibited in the same mutant at 42°C. However, when DNA synthesis is followed in infected cells at 33°C it is found that 1. no degradation of specific DNA seems to occur at 42°C in the early phase of infection, 2. replicating DNA molecules in the late phase of infection are completed at 42°C before DNA synthesis comes to a halt.     

Topological analysis of the fusion process between cellular and subcellular compartments

The study presents an application of the theory of homeomorphic transformations of topological manifolds and the operation of the connected sum of manifolds for topological analysis of membrane transformations during the fusion process between cellular and subcellular compartments. The biological cell and the subcellular structures in the form of vesicles are modelled by an arrangement of two concentric spheres corresponding to the inner and outer layer of the membrane bounding the vesicles. The analysis shows eight succeeding topological stages of membrane transformations during the fusion process and these stages are characterized. It is concluded that there is a vectorial translocation of lipid molecules from the outer layers of the membranes before the fusion process to the internal layer of the membrane bounding the vesicle after the fusion process and there is no lipid translocation in the reverse direction.     

Empirical testing of cryoconite granulation: Role of cyanobacteria in the formation of key biogenic structure darkening glaciers in polar regions

Cryoconite, the dark sediment on the surface of glaciers, often aggregates into oval or irregular granules serving as biogeochemical factories. They reduce a glacier's albedo, act as biodiversity hotspots by supporting aerobic and anaerobic microbial communities, constitute one of the organic matter (OM) sources on glaciers, and are a feeder for micrometazoans. Although cryoconite granules have multiple roles on glaciers, their formation is poorly understood. Cyanobacteria are ubiquitous and abundant engineers of cryoconite hole ecosystems. This study tested whether cyanobacteria may be responsible for cryoconite granulation as a sole biotic element. Incubation of Greenlandic, Svalbard, and Scandinavian cyanobacteria in different nutrient availabilities and substrata for growth (distilled water alone and water with quartz powder, furnaced cryoconite without OM, or powdered rocks from glacial catchment) revealed that cyanobacteria bind mineral particles into granules. The structures formed in the experiment resembled those commonly observed in natural cryoconite holes: they contained numerous cyanobacterial filaments protruding from aggregated mineral particles. Moreover, all examined strains were confirmed to produce extracellular polymeric substances (EPS), which suggests that cryoconite granulation is most likely due to EPS secretion by gliding cyanobacteria. In the presence of water as the only substrate for growth, cyanobacteria formed mostly carpet-like mats. Our data empirically prove that EPS-producing oscillatorialean cyanobacteria isolated from the diverse community of cryoconite microorganisms can form granules from mineral substrate and that the presence of the mineral substrate increases the probability of the formation of these important and complex biogeochemical microstructures on glaciers.     

Characterization of chicken gizzard calcyclin and examination of its interaction with caldesmon

Using a procedure developed to purify calcyclin from mouse Ehrlich ascites tumor cells calcyclin was purified from smooth muscle of chicken gizzard. Chicken gizzard calcyclin bound to phenyl-Sepharose in a calcium dependent manner as did mouse EAT cells and rabbit lung calcyclin but appeared to be more acidic than its mammalian counterparts as revealed by ion exchange chromatography on Mono Q. Chicken gizzard calcyclin bound ⁴⁵Ca²⁺ on nitrocellulose filters and exhibited a shift in electrophoretic mobility on urea-PAGE depending on Ca²⁺ concentration. Crosslinking experiments with BS³ showed that chicken gizzard calcyclin was able to form noncovalent dimers. As indicated by a decrease in maximum tryptophan fluorescence emission of caldesmon (about 14% at 1:1 molar ratio) and displacement of calmodulin from its complex with caldesmon, chicken gizzard calcyclin binds caldesmon. This binding was, however, much weaker than that of calmodulin and could not influence the interaction of caldesmon with actin. In consequence, calcyclin was unable to reverse the inhibitory effect of caldesmon on actin-activated Mg²⁺-ATPase activity of myosin in the presence of Ca²⁺.     

Topological model of the division process of cellular and subcellular compartments

The application of the theory of homeomorphic transformations of topological manifolds and the operation of the connected sum of manifolds for a formation of a topological model of membrane transformations during the division process of cellular and subcellular compartments, has been shown. The biological cell and the subcellular structures in the form of vesicles are modelled by an arrangement of two concentric spheres corresponding to the inner and outer layer of the membrane bounding the vesicle. The analysis shows eight succeeding topological stages of membrane transformations during the division process and these stages are characterised. It is concluded that there is a vectorial translocation of lipid molecules from the inner layer of the membrane bounding the vesicle before the division process to the outer layer of the membranes after the division process and there is no lipid translocation from the outer layer to the inner layers during the division process.