Characterization by cytofluorometry of the different types of adenohypophyseal cells in the rat

The different antehypophysical cell types which synthetize and release somatotroph (GH), corticothroph (ACTH), gonadotroph (LH-FSH) and lactotroph (PRL) hormones were analysed. The experiments were performed on hypophyses from five groups of animals: adult males, 14 days-old female, adult females, gestating adult females and lactating adult females. The cells were analysed by immunofluorescence using flow cytometry. For each of the hormones studied, there was a characteristic spectral distribution of cells. The evolution of cell size and granular content with respect to sex and physiological state of each group was studied by the analysis of diffused light. Small, slightly granular cells represented 50% of the cell population in males and 14 day-old females but only 8% in gestating or lactating females. The study of the cell cycle showed the presence of dividing cells in the population of large, granular cells from gestating and from lactating females. No features of cell division were observed in the population of small, slightly granular cells. This study indicates the potential value of multiparametric analysis in the separation of pure sub-populations of antehypophysial cells.     

Mechanism of Antifungal Action of 2,4,5,6-Tetrachloroisophthalonitrile

Studies of the toxicity of 2,4,5,6-tetrachloroisophthalonitrile (TCIN) to cells of Saccharomyces pastorianus and Neurospora crassa showed that 2 to 4 μg/ml of the toxicant were required to inhibit growth. Several thiol compounds reversed toxicity to growth. Glucose oxidation was severely impaired in treated cells of both test organisms. The toxicant at 2 or 4 μg/ml markedly reduced soluble thiol content of these cells. Bound thiol content was less affected in S. pastorianus cells than soluble thiol content. Uptake of toxicant by yeast cells was accompanied by formation of derivatives, some of which resembled those formed by reaction of glutathione with TCIN in vitro. Coenzyme A, glutathione, and 2-mercaptoethanol readily formed derivatives with TCIN in vitro. The nature of these derivatives was studied using 2-mercaptoethanol products as model substituents. Four derivatives were formed with 2-mercaptoethanol each with similar functional groups but showing dissimilar degrees of mobility during silica gel chromatography. Evidence indicated that these are derivatives of TCIN in which 1 to 4 of the halogens has been substituted by 2-mercaptoethanol. The mechanism of fungicidal action of TCIN is attributed to thiol inactivation.     

Methods of detection and estimation of rhizobia in soil

Summary The plant-infection technique for the estimation of rhizobia, in which small-seeded hosts are grown on agar within test-tubes, is applicable to soils with a moderate rhizobial population (in the order of at least 100/g). Account might have to be taken of skips (less diluted: negative, when more diluted are positive) likely to result, at least in part, from unfavourable conditions for rhizobial survival, multiplication or nodulation. Because of such effects, a sparse population (in the order of (10/g) may not be detected even without dilution (1 g soil per plant tube). Localisation of rhizobia in the soil is likely to be important in determining contact with the plant roots in the dilution count and in sampling from the field. Difficulties with sparsely populated soils can be partly overcome by carefully conducted direct sowings of sterilised seed, preferably in the confines of cores, either left in the field or brought back to the glasshouse.     

The polymorphic marker DXS304 is within 5 centimorgans of the fragile X locus

The fragile X syndrome, which is the most common cause of inherited mental retardation, poses important diagnostic problems for genetic counseling. The development of diagnostic strategies based on DNA analysis has been impaired by the lack of polymorphic markers very close to the disease locus. Here we report that the polymorphic probe U6.2 (locus DXS304) is much closer to the fragile X locus than all the previously reported markers. A recombination fraction of 0.02 between DXS304 and the fragile X locus was estimated by multipoint linkage analysis (confidence interval 0.002 to 0.05). Our data suggest that DXS304 is distal to the fragile X locus. This marker thus represents a major improvement for carrier detection and prenatal diagnosis in fragile X families.     

Global mangrove root production,its controls and roles in the blue carbon budget of mangroves

Mangroves are among the most carbon-dense ecosystems worldwide. Most of the carbon in mangroves is found belowground, and root production might be an important control of carbon accumulation, but has been rarely quantified and understood at the global scale. Here, we determined the global mangrove root production rate and its controls using a systematic review and a recently formalised, spatially explicit mangrove typology framework based on geomorphological settings. We found that global mangrove root production averaged ~770 ± 202 g of dry biomass m⁻² year⁻¹ globally, which is much higher than previously reported and close to the root production of the most productive tropical forests. Geomorphological settings exerted marked control over root production together with air temperature and precipitation (r² ≈ 30%, p < .001). Our review shows that individual global changes (e.g. warming, eutrophication, drought) have antagonist effects on root production, but they have rarely been studied in combination. Based on this newly established root production rate, root-derived carbon might account for most of the total carbon buried in mangroves, and 19 Tg C lost in mangroves each year (e.g. as CO₂). Inclusion of root production measurements in understudied geomorphological settings (i.e. deltas), regions (Indonesia, South America and Africa) and soil depth (>40 cm), as well as the creation of a mangrove root trait database will push forward our understanding of the global mangrove carbon cycle for now and the future. Overall, this review presents a comprehensive analysis of root production in mangroves, and highlights the central role of root production in the global mangrove carbon budget.