Seasonal movements of river dolphins (Inia geoffrensis) in a protected Amazonian floodplain

Deliberate killing for use as bait in a regional catfish (Calophysus macropterus) fishery is the primary threat affecting the survival of the Amazon river dolphin, or boto (Inia geoffrensis). Establishing and improving freshwater protected areas has been suggested as a possible course of action to protect the species. However, the ecology of the boto is poorly understood and more information is needed on the species’ habitat use and movement patterns to ensure that spatial protection initiatives meet conservation needs. In this study, mark‐recapture/resight data collected in and near the Mamirauá Sustainable Development Reserve, a várzea in the Brazilian Amazon, was used to examine transition probabilities of botos between various habitat types. Our findings suggest that it is imperative that spatial protection initiatives focused on the boto take into account the importance of várzea habitat and bay systems for individuals in early life stages. Moreover, because botos frequently occupy the main rivers, particularly during the low water period, protecting areas of the main river waters adjacent to várzeas could aid in the protection of hunted populations.     

Specific foetal growth rates of cetaceans

The numerous data in the International Whaling Statistics relating foetal length to date of catch have been studied. They can be used as alternatives to cube roots of foetal weights to give rates of foetal growth and for the computation of data of conception and foetal ages. There are major differences between the Mysticeti and Odontoceti. The main gestation period for the former is 10.8.±1-2 months and for the latter 14 ± 2 months. In both groups the greatest birth-weight is attained by an increased foetal growth rate, to such an extent in the rorquals that the gestation period in the largest is actually shorter than in the smaller species. There are dietetic and metabolic differences between the two sub-cohorts. The outstanding one is that pregnant mysticetes appear to stop feeding and lose body fat to the foetus during late pregnancy, at the time when the foetal increase in size is maximal. The causes of the differences in growth and metabolism of the two groups are unknown, apart from those imposed by differences in their ecology.     

Anaerobic c(1) metabolism of the o-methyl-C-labeled substituent of vanillate

The O-methyl substituents of aromatic compounds constitute a C(1) growth substrate for a number of taxonomically diverse anaerobic acetogens. In this study, strain TH-001, an O-demethylating obligate anaerobe, was chosen to represent this physiological group, and the carbon flow when cells were grown on O-methyl substituents as a C(1) substrate was determined by C radiotracer techniques. O-[methyl-C]vanillate (4-hydroxy-3-methoxy-benzoate) was used as the labeled C(1) substrate. The data showed that for every O-methyl carbon converted to [C]acetate, two were oxidized to CO(2). Quantitation of the carbon recovered in the two products, acetate and CO(2), indicated that acetate was formed in part by the fixation of unlabeled CO(2). The specific activity of C in acetate was 70% of that in the O-methyl substrate, suggesting that only one carbon of acetate was derived from the O-methyl group. Thus, it is postulated that the carboxyl carbon of the product acetate is derived from CO(2) and the methyl carbon is derived from the O-methyl substituent of vanillate. The metabolism of O-[methyl-C]vanillate by strain TH-001 can be described as follows: 3CH(3)OC(7)H(5)O(3) + CO(2) + 4H(2)O --> CH(3)COOH + 2CO(2) + 10H + 10e + 3HOC(7)H(5)O(3).     

A mathematical description of pressures in alveolar pores of Kohn

Small interalveolar holes within the lung are called pores of Kohn. Some researchers have correlated enlarged pore size with diseases, e.g. emphysema, that are characterized by tissue destruction. Mathematical models of the pressures generated in closed, fluid-filled and open, fluid-lined pores demonstrate that pressures capable of rupturing lung tissue can be developed in a pore due to the surface tension and shape of the air-liquid interface. Pore enlargement accompanied by tissue destruction is presented as a possible mechanism for the disease process observed during aging and the development of emphysema in the lung.     

Dispersed growth of Streptomyces in liquid culture

Summary The study of the physiology of the filamentous bacterium Streptomyces is inhibited by its formation of mycelial pellets in liquid cultures. It is demonstrated that dispersed growth may be achieved by the addition of polymers to the culture medium. Uncharged polymers, such as polyethylene glycol, are relatively ineffective but polyanions such as agar, Carbopol and Junlon produce dispersed cultures when included in a defined growth medium at low concentrations. Junlon-containing media enable optical density measurements to be used to follow batch growth of Streptomyces. Improvements in both biomass yield and product yield of the pigmented antibiotic actinorhodin were found to result from the incorporation of Junlon into minimal medium.     

Growth and reproduction ofPorphyra columbina Mont. (Bangiales,Rhodophyceae) from southern New Zealand

Changes in biomass and chemical composition, and the reproductive phenology ofPorphyra columbina Mont. were monitored at three sites in southern New Zealand over two growing seasons. Both temporal and spatial variations were found. Seasonal changes in biomass and chemical components were correlated with seawater nitrate concentrations and temperature. The summer decline in biomass was a result of the onset of unsuitable environmental conditions and the release of reproductive tissue. Under more suitable conditions, the decline in biomass was delayed. There was an inverse relationship between vegetative growth and reproduction. Reproductive plants first appeared in August at a time of increasing temperature, irradiance and daylength. Only larger plants which were mainly found in subsites low on the shore became reproductive. Plants sampled from high subsites had a shorter growth season, were generally smaller, had lower nitrogen and pigment content and were non-reproductive.Presented at the XIIIth International Seaweed Symposium, University of British Columbia, Vancouver, Canada, August 1989.     

The Kinematics of Cytotoxic Lymphocytes Influence Their Ability to Kill Target Cells

Cytotoxic lymphocytes (CTL) have been reported to show a range of motility patterns from rapid long-range tracking to complete arrest, but how and whether these kinematics affect their ability to kill target cells is not known. Many in vitro killing assays utilize cell lines and tumour-derived cells as targets, which may be of limited relevance to the kinetics of CTL-mediated killing of somatic cells. Here, live-cell microscopy is used to examine the interactions of CTL and primary murine skin cells presenting antigens. We developed a qualitative and quantitative killing assay using extended-duration fluorescence time-lapse microscopy coupled with large-volume objective software-based data analysis to obtain population data of cell-to-cell interactions, motility and apoptosis. In vivo and ex vivo activated antigen-specific cytotoxic lymphocytes were added to primary keratinocyte targets in culture with fluorometric detection of caspase-3 activation in targets as an objective determinant of apoptosis. We found that activated CTL achieved contact-dependent apoptosis of non-tumour targets after a period of prolonged attachment – on average 21 hours – which was determined by target cell type, amount of antigen, and activation status of CTL. Activation of CTL even without engagement of the T cell receptor was sufficient to mobilise cells significantly above baseline, while the addition of cognate antigen further enhanced their motility. Highly activated CTL showed markedly increased vector displacement, and velocity, and lead to increased antigen-specific target cell death. These data show that the inherent kinematics of CTL correlate directly with their ability to kill non-tumour cells presenting cognate antigen.     

Sequence Variants of the POMC Gene and Their Associations with Body Composition in Children

We investigated POMC sequence variants in 242 overweight and nonoverweight African‐American and white children and examined the associations between body composition and POMC polymorphisms. Three novel polymorphisms and two previously identified sequence variants were found: A7301G, A7429G, and C8246T were all in untranslated regions. A 9‐bp (AGC AGC GGC) duplication/insertion was found between positions 7677 and 7678, and one normal‐weight African‐American girl had a 45‐bp triple duplication/insertion at this location. Compared with whites, African‐American children were significantly more likely to have polymorphisms A7301G, A7429G, and the 9‐bp insertion. However, there were no significant associations between any of the polymorphisms and body composition. Five African‐American subjects who were homozygous for A7429G had a trend (p = 0.08) for a greater BMI‐SD score (5.3 ± 5.3 kg/m²) compared with wild‐type children (BMI‐SD score, 2.4 ± 3.2 kg/m²) or heterozygotes (BMI‐SD score, 2.7 ± 3.7 kg/m²). However, there were no differences in BMI‐SD score for A7429G when African American subjects were studied separately and both gender and height were taken into account. The contribution of the POMC gene variants we studied to pediatric‐onset obesity seems to be limited.     

In vitro human keratinocyte migration rates are associated with SNPs in the KRT1 interval

Efforts to develop effective therapeutic treatments for promoting fast wound healing after injury to the epidermis are hindered by a lack of understanding of the factors involved. Re-epithelialization is an essential step of wound healing involving the migration of epidermal keratinocytes over the wound site. Here, we examine genetic variants in the keratin-1 (KRT1) locus for association with migration rates of human epidermal keratinocytes (HEK) isolated from different individuals. Although the role of intermediate filament genes, including KRT1, in wound activated keratinocytes is well established, this is the first study to examine if genetic variants in humans contribute to differences in the migration rates of these cells. Using an in vitro scratch wound assay we observe quantifiable variation in HEK migration rates in two independent sets of samples; 24 samples in the first set and 17 samples in the second set. We analyze genetic variants in the KRT1 interval and identify SNPs significantly associated with HEK migration rates in both samples sets. Additionally, we show in the first set of samples that the average migration rate of HEK cells homozygous for one common haplotype pattern in the KRT1 interval is significantly faster than that of HEK cells homozygous for a second common haplotype pattern. Our study demonstrates that genetic variants in the KRT1 interval contribute to quantifiable differences in the migration rates of keratinocytes isolated from different individuals. Furthermore we show that in vitro cell assays can successfully be used to deconstruct complex traits into simple biological model systems for genetic association studies.