Contribution of sucrose synthase, ADP-glucose pyrophosphorylase and starch synthase to starch synthesis in developing pea seeds

Using genetic variability existing amongst nine pea genotypes (Pisum sativum L.), the biochemical basis of sink strength in developing pea seeds was investigated. Sink strength was considered to be reflected by the rate of starch synthesis (RSS) in the embryo, and sink activity in the seed was reflected by the relative rate of starch synthesis (RRSS). These rates were compared to the activities of three enzymes of the starch biosynthetic pathway [sucrose synthase (Sus), ADP-glucose pyrophosphorylase and starch synthase] at three developmental stages during seed filling (25, 50 and 75% of the dry seed weight). Complete sets of data collected during seed filling for the nine genotypes showed that, for all enzyme activities (expressed on a protein basis), only Sus in the embryo and seed coat was linearly and significantly correlated to RRSS. The contribution of the three enzyme activities to the variability in RSS and RRSS was evaluated by multiple regression analysis for the first two developmental stages. Only Sus activity in the embryo could explain, at least in part, the significant variability observed for both the RSS and the RRSS at each developmental stage. We conclude that Sus activity is a reliable marker of sink activity in developing pea seeds.     

Sea urchin Hox genes: insights into the ancestral Hox cluster

We describe the Hox cluster in the radially symmetric sea urchin and compare our findings to what is known from clusters in bilaterally symmetric animals. Several Hox genes from the direct-developing sea urchin Heliocidaris erythrogramma are described. CHEF gel analysis shows that the Hox genes are clustered on a < or = 300 kilobase (kb) fragment of DNA, and only a single cluster is present, as in lower chordates and other nonvertebrate metazoans. Phylogenetic analyses of sea urchin, amphioxus, Drosophila, and selected vertebrate Hox genes confirm that the H. erythrogramma genes, and others previously cloned from other sea urchins, belong to anterior, central, and posterior groups. Despite their radial body plan and lack of cephalization, echinoderms retain at least one of the anterior group Hox genes, an orthologue of Hox3. The structure of the echinoderm Hox cluster suggests that the ancestral deuterostome had a Hox cluster more similar to the current chordate cluster than was expected Sea urchins have at least three Abd-B type genes, suggesting that Abd-B expansion began before the radiation of deuterostomes.      

Concealed by darkness: interactions between predatory bats and nocturnally migrating songbirds illuminated by DNA sequencing

Recently, several species of aerial‐hawking bats have been found to prey on migrating songbirds, but details on this behaviour and its relevance for bird migration are still unclear. We sequenced avian DNA in feather‐containing scats of the bird‐feeding bat Nyctalus lasiopterus from Spain collected during bird migration seasons. We found very high prey diversity, with 31 bird species from eight families of Passeriformes, almost all of which were nocturnally flying sub‐Saharan migrants. Moreover, species using tree hollows or nest boxes in the study area during migration periods were not present in the bats’ diet, indicating that birds are solely captured on the wing during night‐time passage. Additional to a generalist feeding strategy, we found that bats selected medium‐sized bird species, thereby assumingly optimizing their energetic cost‐benefit balance and injury risk. Surprisingly, bats preyed upon birds half their own body mass. This shows that the 5% prey to predator body mass ratio traditionally assumed for aerial hunting bats does not apply to this hunting strategy or even underestimates these animals’ behavioural and mechanical abilities. Considering the bats’ generalist feeding strategy and their large prey size range, we suggest that nocturnal bat predation may have influenced the evolution of bird migration strategies and behaviour.     

Dispersal and group formation dynamics in a rare and endangered temperate forest bat (Nyctalus lasiopterus,Chiroptera: Vespertilionidae)

For elusive mammals like bats, colonization of new areas and colony formation are poorly understood, as is their relationship with the genetic structure of populations. Understanding dispersal and group formation behaviors is critical not only for a better comprehension of mammalian social dynamics, but also for guiding conservation efforts of rare and endangered species. Using nuclear and mitochondrial markers, we studied patterns of genetic diversity and differentiation among and within breeding colonies of giant noctule bats (Nyctalus lasiopterus), their relation to a new colony still in formation, and the impact of this ongoing process on the regionwide genetic makeup. Nuclear differentiation among colonies was relatively low and mostly nonsignificant. Mitochondrial variation followed this pattern, contrasting with findings for other temperate bat species. Our results suggest that this may indicate a recent population expansion. On average, female giant noctules were not more closely related to other colony members than to foreign individuals. This was also true for members of the newly forming colony and those of another, older group sampled shortly after its formation, suggesting that contrary to findings for other temperate bats, giant noctule colonies are not founded by relatives. However, mother–daughter pairs were found in the same populations more often than expected under random dispersal. Given this indication of philopatry, the lack of mitochondrial differentiation among most colonies in the region is probably due to the combination of a recent population expansion and group formation events.     

Bioactive polymers. 56: urease immobilization on carboxymethylcellulose

This article reports on the reaction of urease immobilization through its covalent bonding on carboxymethylcellulose. The reaction is activated by dicyclohexylcarbodiimide. The coupling reaction is influenced by the enzyme-support and activator-support ratios, as well as by duration. Starting from a rotating, composed experimental program of the second order, the function correlating the activity of the immobilized enzyme with the reaction parameters is established. Immobilized urease exhibits thermal stability higher than that of free enzyme, regarding both pH and the inhibiting action of some metal ions or organic substances. The stability over time of the immobilized urease is high, its enzymatic activity being maintained at over 85% of the initial value three months after synthesis.     

In vitro effects of pulsed near-ultraviolet laser exposure on human larynx carcinoma cells.

Effects of pulsed near-ultraviolet laser beam on structural characteristics and macromolecular synthesis of carcinoma HEp2 cells were investigated. Laser irradiation damage induced in these eukaryotic cells could be characterized by two development stages: a) a reversible stage with minor morphological damages (1.5 kJ/m2) and 2) an irreversible one, at higher fluences, characterized by cellular membrane damage, necrobiosis and cells detachment from the substrate (4.5 kJ/m2). A. Studies performed referring to macromolecular syntheses of low laser fluences (1.5 kJ/m2)--irradiated HEp2 cells showed the following aspects: a) syntheses inhibiton phase in the first cycles of cellular replication and b) syntheses stimulation phases in the following cycle with total repair of laser-induced molecular lesions. B. At high laser fluences (3-4.5 kJ/m2), metabolic lesions repair was partially or totally blocked after prolonged culturing at 37 degrees C. Ths paper suggests some mechanisms of laser action on macromolecular synthesis and correlates them with morphological changes induced by laser exposure of carcinoma cells.     

Climate–growth relationship of tree species from a mixed stand of Apuseni Mts., Romania

We present the first results of a dendroecological investigation on three prevailing species growing in the Apuseni Mountains. In this study we succeeded in building up about 200-year long local master chronologies for spruce, fir and beech. These chronologies will serve as a reference for crossdating of (sub-fossil) logs that were preserved in ice caves at the Apuseni Mts.

The analysis of climate–growth relationship provided interesting and different results for the three studied species: we found significant correlations between the beech chronology and the mean temperature of the prior July, autumn and January of the actual year as well as the weather conditions at the beginning of the vegetation period. Conifers yielded coherent results for the mean temperature of prior July and sum of precipitation in April. In addition, fir seems to be favouring above-average temperatures in January and February. The coherent and significant correlations with the April precipitation suggest a common coniferous phenomenon. Finally, beech index showed negative correlation with April temperature.     

Epidemiological surveillance of syphilis patients in Colentina Hospital (Bucharest, Romania)

Syphilis remains a global health problem with an estimated 12 million people infected each year. In Romania a decrease in the syphilis prevalence can be observed. From 2002 (12,702 cases) and 2003 (9,698 cases) until 2006 (5,657 syphilis cases) the reduction can be explained through the intensified efforts of the Ministry of Pubic Health to fight STI. The decrease is probably not related to an improvement of the general health status and not a consequence of some epidemiological prevention and control measures but probably was done by the reorientation of the patients to the general practitioners and to the private practice medical offices and to the lack of reporting of the cases. In Colentina Hospital a similar abrupt decrease of new cases was registered from 2004 (259 cases) to 2006 (110 cases). General problems related to syphilis cases recorded at Colentina Hospital included the patient presentation for consultation in the advanced stages of the disease, the socio-economic and educational factors, proxenetism and the sexual aggression of minors. There is a need in strengthening of the public health component in the control and surveillance of HIV/AIDS and STI. This may need changes in the legal framework to improve reporting and to target vulnerable groups in prevention activities. Laboratory capacity needs to be increased in order to be able to properly diagnose STI and improve the control and patient management. The reporting needs to be improved and simplified as for reporting protocol, reporting forms, case definitions to be taken into account in the renewed STI surveillance.