The flight of pipistrelle bats Pipistrellus pipistrellus during pregnancy and lactation

A group of 20 pipistrelle bats were taken into captivity and allowed free flight and association within a flight room where they gave birth to and successfully reared 17 young. The flight of the females was recorded during pregnancy, early lactation and post-lactation by using stroboscopic stereophotogrammetry (153 flights reconstructed in total). During the investigation body mass was altering owing to reproductive condition, and changes in mass were recorded daily for all (adult and juvenile) bats during the entire study period, which lasted from two weeks before the last birth until release, when the oldest baby was 43 days old. All bats were individually marked, and detailed morphological measurements were made. Pregnant and post-lactating bats were heavier than lactating bats, which showed the lowest wingbeat frequencies. The flight speeds of pregnant, lactating and post-lactating bats showed no significant differences, and this may be because the pregnant bats appeared to have a wider scope for selecting flight speed than the other two reproductive groups, or than animals studied previously. The group of bats as a whole decreased flight speed (scaling as M^-043) and increased wingbeat frequency (scaling as M^0.58) as their mass increased. Wingbeat amplitude showed no relation to body mass, wing area or span, flight speed or frequency. A flight performance model applied to the experimental results and optimum flight conditions is used to predict cost of transport and mechanical power for steady flight, and equilibrium wingbeat amplitude which is compared with observations.     

Evidence of biotic resistance to exotic plant invasion in degraded Bornean forests

Intact tropical forests are generally considered to be resistant to invasions by exotic species, although the shrub Clidemia hirta (Melastomataceae) is highly invasive in tropical forests outside its native range. Release from natural enemies (e.g., herbivores and pathogens) contributes to C. hirta invasion success where native melastomes are absent, and here we examine the role of enemies when C. hirta co-occurs with native Melastomataceae species and associated herbivores and pathogens. We study 21 forest sites within agricultural landscapes in Sabah, Malaysian Borneo, recording herbivory rates in C. hirta and related native Melastoma spp. plants along two 100-m transects per site that varied in canopy cover. Overall, we found evidence of enemy release; C. hirta had significantly lower herbivory (median occurrence of herbivory per plant = 79% of leaves per plant; median intensity of herbivory per leaf = 6% of leaf area) than native melastomes (93% and 20%, respectively). Herbivory on C. hirta increased when closer to native Melastoma plants with high herbivory damage, and in more shaded locations, and was associated with fewer reproductive organs on C. hirta. This suggests host-sharing by specialist Melastomataceae herbivores is occurring and may explain why invasion success of C. hirta is lower on Borneo than at locations without related native species present. Thus, natural enemy populations may provide a “biological control service” to suppress invasions of exotic species (i.e., biotic resistance). However, lower herbivory pressures in more open canopy locations may make highly degraded forests within these landscapes more susceptible to invasion.     

Bycatch: from emotion to effective natural resource management

Although bycatch has been an acknowledged component of fishery management for many years, its explosive growth as a major management issue has occurred over the past decade. Emergence of the bycatch issue can be traced to increasing world competition for the ocean's fishery resources and the rapid rise of the conservation and environmental movement in recent years. Bycatch has in the past several years been equated to waste, non-selective fishing methods that threaten non-target species and degradation of ocean ecosystems. Although some important steps have been taken to abate bycatch, frequently the problem is not perceived as a component of fishery management, e.g. establishing bycatch mortality rates and evaluating their consequences upon affected populations. Fishery scientists often estimate levels of bycatch, but the overall consequences of discard mortality resulting from the complex of fisheries operating in a region are frequently unknown and speculative. The sum of fishery-induced mortalities occurring as a result of harvesting often involves a significant number of fish in addition to catch and discard. An ICES study group has characterized fishing mortality as the aggregate of all catch mortalities including discard, illegal fishing and misreporting. It is unlikely that managers will, in the near future, have a full accounting of unobserved fishing mortality. Progress toward identifying and measuring such mortalities is receiving increasing attention.The authors suggest and provide an example of a matrix-type analysis for recording bycatch and other fishing mortalities. The matrix presentation would allow managers to evaluate various fishery-related mortality factors and their importance in developing management strategies.     

Fertility control using intrauterine devices: an alternative for population control in wild horses

The purpose of this study was to develop a contraceptive method for feral horses. The feral horse population has increased significantly in recent years despite attempts to control numbers. As in most wild animal population control programs, contraceptive methods must be easy to apply, cause minimal disruption to the social structure and be fully reversible. In the present study, we tested the effectiveness of an intrauterine device (IUD) for fertility control in mares. Six mares were fitted with a silastic O-ring-shaped IUD on July 1 of Year 1. The IUD-treated mares were turned out with 12 nontreated mares and a fertile stallion in a large pasture until October 20 (112 d). None of the IUD-treated mares and all the nontreated mares became pregnant. The IUD-treated mares were maintained separately from the stallion during the winter. Following removal of the IUD on April 27 of Year 2, the mares were again introduced to the pasture with the stallion together with 6 nontreated mares. For the 6 mares previously treated with an IUD, the mean interval from introduction to the stallion to conception was 17.5 +/- 5 d or 1.3 cycles per pregnancy, and all mares produced a normal foal at term. Subsequently, 19 recorded mare breeding seasons resulted in 18 foals. Uterine cytology and histopathology indicate that the IUD causes mild chronic endometritis without permanent changes in the endometrium. We conclude that based on our observations, the O-ring-shaped IUD is an effective, safe and practical contraceptive method for mares.     

5-Azacytidine increases the activity of neomycin phosphotransferase II in transgenic Nicotiana tabacum: A posttranslational mechanism may play a role

In previous studies, tobacco protoplasts were transformed with the bacterial gene encoding neomycin phosphotransferase II (NPT II). Transformed calluses lost neomycin phosphotransferase II activity after several subcultures. Treatment of calluses with 5-azacytidine, a demethylating agent, restored enzyme activity, suggesting that methylation of npt II sequences might be responsible for loss of NPT II activity. Studies presented here were designed to test that hypothesis. Results indicated that the effect of 5-azacytidine could not be blocked by the DNA replication inhibitor, hydroxyurea, nor by the 5-azacytidine analogue, cytidine as would be expected with a DNA demethylation mechanism. The level of NPT II mRNA was not increased by 5-azacytidine. Treatment with cycloheximide, a protein synthesis inhibitor, had no effect on 5-azacytidine-increased NPT II activity. There was no increase of NPT II protein caused by 5-azacytidine, whereas 5-azacytidine increased activity of NPT II. In contrast, the auxin 2,4-D increased both the NPT II protein and activity. Assays for malate dehydrogenase demonstrated that the effect of 5-azacytidine and hydroxyurea on NPT II was not due to an overall effect on callus metabolism. In vitro studies involving standard bacterial NPT II enzyme and crude extracts from untreated and 5-azacytidine- or hydroxyurea-treated calluses showed that the activity of NPT II added to the untreated extracts was lower than the activity of NPT II added to the extracts from calluses treated with 5-azacytidine or hydroxyurea, indicating that there was an unknown factor (or factors) in callus extracts which affected the activity of NPT II and itself was affected by 5-azacytidine and hydroxyurea treatment. These results suggested that one effect of 5-azacytidine in increasing NPT II activity was posttranslational.Abbreviations ELISA enzyme-linked immunosorbent assay - NOS nopalene synthase - nos DNA segment encoding NOS - NPT II neomycin phosphotransferase - npt II DNA segment encoding NPT II - PAGE polyacrylamide gel electrophoresis     

Sequence, regulation, and functions of fis in Salmonella typhimurium.

The fis operon from Salmonella typhimurium has been cloned and sequenced, and the properties of Fis-deficient and Fis-constitutive strains were examined. The overall fis operon organization in S. typhimurium is the same as that in Escherichia coli, with the deduced Fis amino acid sequences being identical between both species. While the open reading frames upstream of fis have diverged slightly, the promoter regions between the two species are also identical between -49 and +94. Fis protein and mRNA levels fluctuated dramatically during the course of growth in batch cultures, peaking at approximately 40,000 dimers per cell in early exponential phase, and were undetectable after growth in stationary phase. fis autoregulation was less effective in S. typhimurium than that in E. coli, which can be correlated with the absence or reduced affinity of several Fis-binding sites in the S. typhimurium fis promoter region. Phenotypes of fis mutants include loss of Hin-mediated DNA inversion, cell filamentation, reduced growth rates in rich medium, and increased lag times when the mutants are subcultured after prolonged growth in stationary phase. On the other hand, cells constitutively expressing Fis exhibited normal logarithmic growth but showed a sharp reduction in survival during stationary phase. During the course of these studies, the sigma 28-dependent promoter within the hin-invertible segment that is responsible for fljB (H2) flagellin synthesis was precisely located.     

Phylogenetic relationships among transposon-like elements in human and primate DNA

A THE-1 sequence in intron 7 of the human dystrophin gene has been found to represent a new subfamily of THE-1 elements. The sequence is closely related to the MstII family of repetitive sequences and is more like single-copy sequences found in the galago genome than any other THE-1 sequence previously reported. This new THE-1 sequence has been compared with two other complete THE-1 sequences and three related long-terminal repeat elements that we have previously found in intron 7 of the dystrophin gene, and with members of the same family from elsewhere in the primate genome. Parsimony and deletion analysis show that the cluster of THE-1 sequences in intron 7 of the dystrophin gene has arisen from at least three individual insertion events, rather than from the insertion and duplication of a single progenitor sequence. Correspondence to: G.B. Petersen     

Inositol lipid-mediated signalling in response to endothelin and ATP in the mammalian testis

Molecular and Cellular Biochemistry - The testis is a complex organ in which local control is achieved by signalling between its constituent cells. Herein we describe the responses of cultured rat...