Morphometry and growth of sea pen species from dense habitats in the Gulf of St. Lawrence,eastern Canada

We examined four species of sea pen (Anthoptilum grandiflorum, Halipteris finmarchica, Pennatula aculeata and Pennatula grandis) collected from the Gulf of St. Lawrence and mouth of the Laurentian Channel, eastern Canada. An exponential length–weight relationship was found for all four species, where growth in weight was progressively greater than growth in length with increasing colony size. Halipteris finmarchica, P. grandis and P. aculeata presented the better allometric fits, explaining over 80% of the variance. In addition, a count of growth increments visible in transverse sections in 86 A. grandiflorum and 80 P. aculeata samples was made. Presumed ages ranged between 5 and 28 years for A. grandiflorum and 2 and 21 years for P. aculeata. Radiocarbon assays were inconclusive and could not be used to confirm these ages; further age validation is required. Radial growth of the rod is slow during the first years, increasing at intermediate sizes of the colony and slowing down again for large colonies. Similar results were obtained from the relationship between colony length and number of growth increments where a logistic model was the best fit to the data. On average Spearman’s rank correlations showed 11% of shared variance between sea pen length or weight and environmental variables. Bottom temperature and salinity, depth and summer primary production were significantly correlated to sea pen size for most species.     

Olfactory rhythm in the electrical activity of the human amygdaloid nucleus

Summated electrical activity of the human amygdaloid nucleus was investigated in the neurosurgical clinic by chronically implanted electrodes. It was found that odoriferous stimulation of this structure produced bursts of rapid rhythm (20–30 cps, 30–50 µV). The quasisinusoidal waves of olfactory rhythm consist of sinusoidal components which are more pronounced within the 20–30-Hz frequency range. Spindling of 1–3 sec duration occurs at the end of inhalation and the beginning of exhalation in time with breathing. During monorhinal breathing this activity, whose amplitude depends on degree of olfactory stimulation, can only be recorded ipsilaterally. Room air also activates the amygdaloid nucleus, but less strongly than odoriferous substances: No characteristic odor-dependent differences were discovered in the frequency range of the olfactory rhythm within a 20–30-Hz band.Institute of Physiology, Kiev State University, Kiev. Translated from Neirofiziologiya, Vol. 18, No. 1, pp. 61–69, January–February, 1986.     

Dissection of the role of macrophages in triggering T lymphocytes for interleukin 2 production by monoclonal antibody OKT3

Unfractionated human peripheral blood mononuclear cells produce a small amount of interleukin 2 (IL 2) by stimulation with a monoclonal anti-T3 antibody (OKT3) in vitro. The IL 2 production could be greatly augmented by the addition of a phorbol ester, 12-O-tetradecanoyl-phorbol-13-acetate (TPA). In the presence of TPA, the T cell enriched fraction deprived of macrophages did not produce IL 2, but the T cells pulse-incubated with OKT3 and reconstituted with macrophages efficiently produced IL 2 in subsequent culture in the presence of TPA as did T cells reconstituted with OKT3-pulse-incubated macrophages. The stimulating effect of OKT3 in the presence of macrophages was inhibited dose-dependently by the addition of immunoglobulins, particularly by mouse IgG2a which is the same isotype as that of the OKT3 antibody, showing that it inhibits by blocking the binding of OKT3 to Fc receptors on macrophages. The same extent of IL 2 production was induced in T cells when paraformaldehyde-fixed macrophages were substituted for intact macrophages. Remarkable IL 2 production was also induced by OKT3 when latex beads coated with rabbit anti-mouse IgG2a antibody and TPA were added to the culture. It was confirmed that the production induced by these stimulations was due to an increase of IL 2 mRNA. These results show that effective signals for IL 2 production are generated by efficient crosslinking of T3 molecules which results from multi-interaction of T3 molecules on the T cell membrane and anti-T3 antibody molecules on macrophage membrane or on the surface of the latex particle.     

Developmental regulation and properties of the cGMP-specific phosphodiesterase in Dictyostelium discoideum

A simple assay has been developed to measure cGMP-specific phosphodiesterase (cGPD) activity in crude soluble extracts of amoebae of Dictyostelium discoideum. When amoebae of different wild-type strains were starved on buffered agar, all strains exhibited an 8- to 12-fold increase in cGMP-specific hydrolyzing activity during development, with the major increase occurring at aggregation. cGMP-specific activity was found in both prestalk and prespore cells. To determine if the elevated cGMP-specific hydrolyzing activity observed during late development was associated with the same enzyme present in vegetative cells, cGMP-specific activities were partially purified from cells at different developmental stages and characterized. Activity in vegetative cells was fractionated by gel filtration into three components with molecular weights of approximately 172,000, 115,000 and 56,000. In contrast, cells starved 4 hr in suspension or 18 hr on agar possessed only the 172,000 or 115,000 Mr forms, respectively. The low-molecular-weight enzyme differed from the two larger forms in kinetic properties and in sensitivity to sulfhydryl reagents. Nevertheless, the three activities probably represent different forms of the same enzyme because mutants defective at the stmF locus lacked appreciable cGMP-specific hydrolyzing activity throughout development. These results indicate that D. discoideum produces a single cGPD which is strongly developmentally regulated. These findings further suggest that intracellular cGMP might be involved in regulating postaggregative as well as preaggregative development.     

Spectral composition of shade light in coastal-zone oak forests in SE Bulgaria,and relationships with leaf area index: a first overview

Major knowledge gaps exist with respect to light-quality regimes in the coastal-zone Strandzha Quercus frainetto (Q.f.) forest region adjoining the southern Bulgarian Black Sea. This paper presents preliminary results that help narrow these gaps. In conjunction with leaf area index (LAI) field campaigns we undertook measurements with an array of 7 broad-band (ca 40 nm) sensors covering the range 0.40–0.94 μm, plus 1 sensor for UVB (0.297 μm peak) and 1 for photosynthetically active radiation (PAR). Measurements focused on inside-forest shade conditions at sites 0 to ca 15 km from the Black Sea and at altitudes up to ca 120 m above sea level. Some of the sites were also studied using a high-resolution spectroradiometer. A sequential measuring strategy was necessary. This involves potentially large uncertainties, here addressed through estimations of the variability around the sinusoidal course of daylight. Light-quality regimes were found to be in general support of earlier studies of deciduous forests. Our data from the broad-band sensors and from the spectroradiometer are mutually supportive. They indicate a stronger red-shift below Q.f. canopies than below canopies in enclaves dominated by Fagus orientalis and Pinus sylvestris. Transmission in the range 0.50–0.55 μm increases beneath the three types of canopies, most pronounced in the Q.f. case. Analysis of relationships between the inside-forest to open-field irradiance ratio and LAI supports the use of Beer’s Law. We found a fairly strong relationship between the red (0.66 μm) to far-red (0.73 μm) irradiance ratios (R/FR) and LAI for the Q.f. forest. In quantitative terms, the result is new for this Q.f. region, and suggests further research to explore whether a two-sensor approach (0.66 and 0.73 μm) might offer possibilities for further low-cost mapping of the spatio-temporal patterns of R/FR and LAI in Strandzha. Such mapping would assist in further studies of the region’s forest biogeochemistry and vitality.     

Rapid Antiretroviral Therapy Initiation for Women in an HIV-1 Prevention Clinical Trial Experiencing Primary HIV-1 Infection during Pregnancy or Breastfeeding

During an HIV-1 prevention clinical trial in East Africa, we observed 16 cases of primary HIV-1 infection in women coincident with pregnancy or breastfeeding. Nine of eleven pregnant women initiated rapid combination antiretroviral therapy (ART), despite having CD4 counts exceeding national criteria for ART initiation; breastfeeding women initiated ART or replacement feeding. Rapid ART initiation during primary HIV-1 infection during pregnancy and breastfeeding is feasible in this setting.     

The effects of manipulation of sedimentary iron and organic matter on sediment biogeochemistry and seagrasses in a subtropical carbonate environment

The microbial metabolism of organic matter (OM) in seagrass beds can create sulfidic conditions detrimental to seagrass growth; iron (Fe) potentially has ameliorating effects through titration of the sulfides and the precipitation of iron-sulfide minerals into the sediment. In this study, the biogeochemical effects of Fe availability and its interplay with sulfur and OM on sulfide toxicity, phosphorous (P) availability, seagrass growth and community structure were tested. The availability of Fe and OM was manipulated in a 2 × 2 factorial experiment arranged in a Latin square, with four replicates per treatment. The treatments included the addition of Fe, the addition of OM, the addition of both Fe and OM as well as no addition. The experiment was conducted in an oligotrophic, iron-deficient seagrass bed. Fe had an 84.5% retention efficiency in the sediments with the concentration of Fe increasing in the seagrass leaves over the course of the experiment. Porewater chemistry was significantly altered with a dramatic decrease in sulfide levels in Fe addition plots while sulfide levels increased in the OM addition treatments. Phosphorus increased in seagrass leaves collected in the Fe addition plots. Decreased sulfide stress was evidenced by heavier δ³⁴S in leaves and rhizomes from plots to which Fe was added. The OM addition negatively affected seagrass growth but increased P availability; the reduced sulfide stress in Fe added plots resulted in elevated productivity. Fe availability may be an important determinant of the impact that OM has on seagrass vitality in carbonate sediments vegetated with seagrasses.