Recent Region-wide Declines in Caribbean Reef Fish Abundance

Profound ecological changes are occurring on coral reefs throughout the tropics, with marked coral cover losses and concomitant algal increases, particularly in the Caribbean region. Historical declines in the abundance of large Caribbean reef fishes likely reflect centuries of overexploitation. However, effects of drastic recent degradation of reef habitats on reef fish assemblages have yet to be established. By using meta-analysis, we analyzed time series of reef fish density obtained from 48 studies that include 318 reefs across the Caribbean and span the time period 1955–2007. Our analyses show that overall reef fish density has been declining significantly for more than a decade, at rates that are consistent across all subregions of the Caribbean basin (2.7% to 6.0% loss per year) and in three of six trophic groups. Changes in fish density over the past half-century are modest relative to concurrent changes in benthic cover on Caribbean reefs. However, the recent significant decline in overall fish abundance and its consistency across several trophic groups and among both fished and nonfished species indicate that Caribbean fishes have begun to respond negatively to habitat degradation

Antioxidative protection of dietary bilberry, chokeberry and Lactobacillus plantarum HEAL19 in mice subjected to intestinal oxidative stress by ischemia-reperfusion

<p>Abstract</p> <p>Background</p> <p>Ischemia-reperfusion (I/R) in the intestines is an inflammatory condition which activates leukocytes and reactive oxygen species (ROS) and leads to lipid peroxidation and DNA damage. Bilberry and chokeberry fruits are rich sources of polyphenols which may act as antioxidants and prevent lipid peroxidation. Lactic acid bacteria (LAB) may improve microbial status in the intestines and increase the metabolic activity towards polyphenolic degradation. The aim of the study was to clarify antioxidative effects of bilberry and chokeberry fruits alone and with addition of a LAB-strain, <it>Lactobacillus plantarum </it>HEAL19, in an I/R-model in mice.</p> <p>Methods</p> <p>Male BALB/cJ mice were fed the experimental diets for 10 days. Diets consisted of standard chow supplemented with either bilberry (<it>Vaccinium myrtillus</it>) or chokeberry (<it>Aronia × prunifolia</it>) powder alone or in combination with the LAB-strain <it>Lactobacillus plantarum </it>HEAL19. I/R-injury was induced by holding superior mesenteric artery clamped for 30 minutes followed by reperfusion for 240 minutes. Thereafter, colonic and caecal tissues and contents were collected. Malondialdehyde (MDA) was used as indicator of lipid peroxidation and was measured by a calorimetric assay, lactobacilli were cultured on Rogosa agar plates and <it>Enterobacteriaceae </it>on VRBG agar plates, anthocyanins and phenolic acids were analysed by HPLC-DAD-ESI-MSn.</p> <p>Results</p> <p>MDA was significantly decreased in the colon of groups fed bilberry alone (p = 0.030) and in combination with <it>L. plantarum </it>HEAL19 (p = 0.021) compared to the IR-control but not in chokeberry-fed groups. Supplementation with bilberry or chokeberry alone reduced the total number of lactobacilli on the mucosa. Higher concentrations of anthocyanins were found in the colon than in the caecum content of mice. A more varied composition of different anthocyanins was also observed in the colon content compared to the caecum of bilberry-fed mice. Phenolic acids formed by microbial degradation of the dietary polyphenols in the gut could be detected. More phenolic metabolites were found in the intestines of bilberry-fed mice than in the chokeberry-fed ones.</p> <p>Conclusions</p> <p>Bilberry alone and in combination with <it>L. plantarum </it>HEAL19 exerts a better protection against lipid peroxidation than chokeberry. These dietary supplements may be used to prevent or suppress oxidative stress.</p

Rad21-Cohesin Haploinsufficiency Impedes DNA Repair and Enhances Gastrointestinal Radiosensitivity in Mice

Approximately half of cancer-affected patients receive radiotherapy (RT). The doses delivered have been determined upon empirical experience based upon average radiation responses. Ideally higher curative radiation doses might be employed in patients with genuinely normal radiation responses and importantly radiation hypersensitive patients would be spared the consequences of excessive tissue damage if they were indentified before treatment. Rad21 is an integral subunit of the cohesin complex, which regulates chromosome segregation and DNA damage responses in eukaryotes. We show here, by targeted inactivation of this key cohesin component in mice, that Rad21 is a DNA-damage response gene that markedly affects animal and cell survival. Biallelic deletion of Rad21 results in early embryonic death. Rad21 heterozygous mutant cells are defective in homologous recombination (HR)-mediated gene targeting and sister chromatid exchanges. Rad21+/− animals exhibited sensitivity considerably greater than control littermates when challenged with whole body irradiation (WBI). Importantly, Rad21+/− animals are significantly more sensitive to WBI than Atm heterozygous mutant mice. Since supralethal WBI of mammals most typically leads to death via damage to the gastrointestinal tract (GIT) or the haematopoietic system, we determined the functional status of these organs in the irradiated animals. We found evidence for GIT hypersensitivity of the Rad21 mutants and impaired bone marrow stem cell clonogenic regeneration. These data indicate that Rad21 gene dosage is critical for the ionising radiation (IR) response. Rad21 mutant mice thus represent a new mammalian model for understanding the molecular basis of irradiation effects on normal tissues and have important implications in the understanding of acute radiation toxicity in normal tissues

Declining size of adults and juvenile harvest threatens sustainability of a tropical gastropod, Lobatus gigas

Queen conch (Lobatus gigas) is a large herbivorous gastropod, found across the Caribbean, which forms the basis of important dive fisheries. Conch have a two‐phase shell growth pattern, first in shell length (SL), which ceases well before maturity, followed by growth in shell lip thickness (LT) into maturity. This growth pattern must be considered in determining the ideal size and associated maturity for sustainable harvest. Shell morphology, sex organ development and soft tissue masses indicated that mature adult conchs at Glover's Atoll, Belize, were those with thick shell lips (≥10 mm), eroded shells and heavier soft tissue masses. Therefore, SL‐based regulations cannot serve as a proxy for maturity and harvest. The use of inappropriate minimum size limits (SL = 178 mm, 85 g market clean meat mass) has allowed significant juvenile harvest and the fishery appears to have truncated the SL size distribution of conchs with a flared shell lip (i.e. adults) over the last 15 years. The reduced SL observed in lipped conchs may lead to a significant impact on the reproductive success of the population as well as diminished economic yield from the fishery, as smaller adult conchs of the same age have lower gonad and meat weight. We believe this to be the first documentation of a decline in the SL of adult queen conchs, and that the SL‐based size limits have contributed to this decline. Refinement of the individual size‐based regulations for conch in Belize to LT will probably facilitate local recovery as well as regional harmonization of regulations. Future research in Belize should include movement dynamics of conch in relation to replenishment zone size and spillover as well as the importance of deep‐water conch to shallow‐water recruitment, which is thought to be limited