Evidence for distinct coastal and offshore communities of bottlenose dolphins in the north east Atlantic.

Bottlenose dolphin stock structure in the northeast Atlantic remains poorly understood. However, fine scale photo-id data have shown that populations can comprise multiple overlapping social communities. These social communities form structural elements of bottlenose dolphin (Tursiops truncatus) [corrected] populations, reflecting specific ecological and behavioural adaptations to local habitats. We investigated the social structure of bottlenose dolphins in the waters of northwest Ireland and present evidence for distinct inshore and offshore social communities. Individuals of the inshore community had a coastal distribution restricted to waters within 3 km from shore. These animals exhibited a cohesive, fission-fusion social organisation, with repeated resightings within the research area, within a larger coastal home range. The offshore community comprised one or more distinct groups, found significantly further offshore (>4 km) than the inshore animals. In addition, dorsal fin scarring patterns differed significantly between inshore and offshore communities with individuals of the offshore community having more distinctly marked dorsal fins. Specifically, almost half of the individuals in the offshore community (48%) had characteristic stereotyped damage to the tip of the dorsal fin, rarely recorded in the inshore community (7%). We propose that this characteristic is likely due to interactions with pelagic fisheries. Social segregation and scarring differences found here indicate that the distinct communities are likely to be spatially and behaviourally segregated. Together with recent genetic evidence of distinct offshore and coastal population structures, this provides evidence for bottlenose dolphin inshore/offshore community differentiation in the northeast Atlantic. We recommend that social communities should be considered as fundamental units for the management and conservation of bottlenose dolphins and their habitat specialisations

Repression of Meiotic Genes by Antisense Transcription and by Fkh2 Transcription Factor in Schizosaccharomyces pombe

In S. pombe, about 5% of genes are meiosis-specific and accumulate little or no mRNA during vegetative growth. Here we use Affymetrix tiling arrays to characterize transcripts in vegetative and meiotic cells. In vegetative cells, many meiotic genes, especially those induced in mid-meiosis, have abundant antisense transcripts. Disruption of the antisense transcription of three of these mid-meiotic genes allowed vegetative sense transcription. These results suggest that antisense transcription represses sense transcription of meiotic genes in vegetative cells. Although the mechanism(s) of antisense mediated transcription repression need to be further explored, our data indicates that RNAi machinery is not required for repression. Previously, we and others used non-strand specific methods to study splicing regulation of meiotic genes and concluded that 28 mid-meiotic genes are spliced only in meiosis. We now demonstrate that the “unspliced” signal in vegetative cells comes from the antisense RNA, not from unspliced sense RNA, and we argue against the idea that splicing regulates these mid-meiotic genes. Most of these mid-meiotic genes are induced in mid-meiosis by the forkhead transcription factor Mei4. Interestingly, deletion of a different forkhead transcription factor, Fkh2, allows low levels of sense expression of some mid-meiotic genes in vegetative cells. We propose that vegetative expression of mid-meiotic genes is repressed at least two independent ways: antisense transcription and Fkh2 repression

MUSCULAR STRENGTH AS A PREDICTOR OF BONE MINERAL DENSITY IN COLLEGIATE FEMALE ATHLETES

Emily V. Witte1, Henry N. Williford2, FACSM, Michael R. Esco3, FACSM & Matthew D. Leatherwood2. 1Emporia State University, Emporia, KS; 2Auburn University at Montgomery, Montgomery, AL; 3University of Alabama, Tuscaloosa, AL; e-mail: [email protected] It has been well established that the frequency and duration of impact loading, age, body weight, and body composition are independently correlated with bone mineral density (BMD) in female athletes. However, very little is known about the relationship of strength, in addition to other anthropometric measures, and BMD. PURPOSE: The purpose of this study was to examine the relationship between muscular strength, muscular endurance, sport specific impact loading, age, body composition and body weight simultaneously in regards to BMD in collegiate female athletes. METHODS: Participants included apparently healthy collegiate female athletes from a variety of sports; tennis (n=7), basketball (n=8), soccer (n=7), cross country (n=2), cheer (n=2), and volleyball (n=4). Each subject reported twice during a seven day span to complete the assessments. During the first session, descriptive statistics such as height, weight, BMD and body composition were recorded. Additionally, objective assessments for muscular strength (hand-grip strength, one-repetition max bench press and squat strength), muscular endurance (push-ups and curl-ups) were performed. The second session included the evaluation of maximal oxygen consumption, obtained from a graded exercise test and open circuit spirometry. RESULTS: Using a Pearson correlation, bench press strength displayed the greatest relationship with BMD (r = 0.826). Significant relationships also existed between BMD and fat-free mass (r = 0.739), maximal squat strength (r = 0.666) and hand-grip strength (r = 0.597). A stepwise regression model revealed maximal bench press strength as the most significant variable for predicting total BMD in respect to the variables being measured. In addition, a negative relationship was displayed between BMD and partial curl-ups (r = -0.387) and maximal oxygen uptake (r = -0.360). CONCLUSIONS: These results indicate that the relationship between BMD and muscular strength, particularly maximal bench press strength, may be greater than previously indicated

Limited trophic partitioning among sympatric delphinids off a tropical oceanic atoll

<div><p>Understanding trophic relationships among marine predators in remote environments is challenging, but it is critical to understand community structure and dynamics. In this study, we used stable isotope analysis of skin biopsies to compare the isotopic, and thus, trophic niches of three sympatric delphinids in the waters surrounding Palmyra Atoll, in the Central Tropical Pacific: the melon-headed whale (<i>Peponocephala electra</i>), Gray’s spinner dolphin (<i>Stenella longirostris longirostris</i>), and the common bottlenose dolphin (<i>Tursiops truncatus</i>). δ¹⁵N values suggested that <i>T</i>. <i>truncatus</i> occupied a significantly higher trophic position than the other two species. δ¹³C values did not significantly differ between the three delphinds, potentially indicating no spatial partitioning in depth or distance from shore in foraging among species. The dietary niche area—determined by isotopic variance among individuals—of <i>T</i>. <i>truncatus</i> was also over 30% smaller than those of the other species taken at the same place, indicating higher population specialization or lower interindividual variation. For <i>P</i>. <i>electra</i> only, there was some support for intraspecific variation in foraging ecology across years, highlighting the need for temporal information in studying dietary niche. Cumulatively, isotopic evidence revealed surprisingly little evidence for trophic niche partitioning in the delphinid community of Palmyra Atoll compared to other studies. However, resource partitioning may happen via other behavioral mechanisms, or prey abundance or availability may be adequate to allow these three species to coexist without any such partitioning. It is also possible that isotopic signatures are inadequate to detect trophic partitioning in this environment, possibly because isotopes of prey are highly variable or insufficiently resolved to allow for differentiation.</p></div