Estimating weight�Clength relationships without individual weight data: an application to the American lobster (Homarus americanus) fishery of Long Island Sound

The estimation of weight?Clength relationship of fish species requires having data on individual weight and length. However, individual weight data are often not available because they are too expensive or not feasible to gather and the relationship cannot be explicitly estimated. Yet, in this paper I develop a simple methodology that allows me to estimate a weight?Clength relationship when only aggregate weight data are available. To show its usefulness, the methodology is applied to the American lobster (Homarus americanus) population of Long Island Sound. Results indicate the existence of isometric growth for American lobsters in this geographical location: W = 0.000924L ^2.9619. The estimated relationship is used to predict individual weight of lobsters which are then used to construct biomass indexes for three size classes of lobsters for the time period 1987?C2006. This analysis suggests that is not necessary to invest efforts in collecting individual weight data to be able to construct meaningful indicators of fish population.     

Secondary metabolism in micropropagated <Emphasis Type="Italic">Hypericum perforatum</Emphasis> L. grown in non-aerated liquid medium

Hypericum perforatum L. is a medicinal plant that has been extensively studied because of its bioactive properties. The objective of this study was to establish a system that could lower the cost of in vitro propagation by using liquid medium, as well as to evaluate the secondary metabolism in the systems tested. Nodal segments of H. perforatum were obtained from in vitro shoots and grown in three liquid culture systems: total immersion (TI), partial immersion (PI), and paper bridge support (PB). Semi-solid medium (3 g L⁻¹ Phytagel™) was used as control (SS). The organogenic responses were evaluated, and phenolic compounds, hypericin, and the activity of polyphenol oxidases (PPO) and peroxidases (POX) were quantified. After 80 days of culture, induction and proliferation of adventitious shoots were similar in the PI and SS systems (65.3 and 71.3 shoots, respectively), whereas PB resulted in the fewest shoots per explant (29.5 shoots). Longer shoots were obtained under the PI conditions. Hyperhydricity was observed in the shoots from the TI system. Browning was visible in shoots from the TI and PB systems. The highest concentrations of phenolic compounds and hypericin were observed in shoots derived from PI and PB, at 80 days of culture. POX activity was higher in shoots cultured in PI at 40 days, whereas PPO was significantly more active at 80 days of culture. Likely, POX was more related to shoot growth, whereas PPO played a later role in response to the culture environment and medium stress.     

Male and female agonistic and affiliative relationships in a social group of farm cats (Felis catus L.)

A dominance hierarchy based on the outcome of agonistic encounters was found among male and female domestic cats. A female dominated over some males. The dominance concept is also discussed in terms of social bonding. The relationships among adult females were amicable, whereas adult males showed reciprocal tolerance. The flow of affiliative behaviour was directed mainly from females to one male of the group. The analysis of marking behaviour showed that this male sprayed urine and rubbed the perioral and cheek regions of the face on the objects of the environment at a higher rate than the other members of the group. Nevertheless, rubbing the perioral and cheek regions of the face on objects was not correlated to dominance rank, possibly because it has some function in social communication other than territorial defence against strangers. No relationships have been found between claw scratching, rolling on the ground and social rank, or between the former and other marking behaviour. It is concluded that claw scratching and rolling were not utilised to mark territory.     

Identification of vascular endothelial cells in murine omentum using the lectin, Dolichos biflorus agglutinin: possible applications in the study of angiogenesis

Summary The purpose of this study was to determine whether the plant lectin,Dolichos biflorus agglutinin (DBA), can be used to recognize capillary endothelial cells and their processes during angiogenesis. By means of a peroxidase conjugate of DBA, blood vessels were visualized in whole mounts and ultrathin sections of mouse omentum. A part of this mesentery normally comprises an avascular membrane that is approximately 30 µm in thickness. Changes in the vascular plexus bordering this membrane were induced by intraperitoneal injection of irradiated Landschutz cells. Vascular endothelial cells were precisely and intensely stained, and vasculogenic processes were reliably distinguished from those of other cells. This technique permitted observation of the structure and distribution of capillary sprouts, and their relationship to each other and to pre-existing blood vessels. It was discovered that filiform projections extend from sprout apices. These projections may fuse allowing adjacent sprouts to form a new capillary loop.