Reproductive resilience: a paradigm shift in understanding spawner‐recruit systems in exploited marine fish

A close relationship between adult abundance and stock productivity may not exist for many marine fish stocks, resulting in concern that the management goal of maximum sustainable yield is either inefficient or risky. Although reproductive success is tightly coupled with adult abundance and fecundity in many terrestrial animals, in exploited marine fish where and when fish spawn and consequent dispersal dynamics may have a greater impact. Here, we propose an eco‐evolutionary perspective, reproductive resilience, to understand connectivity and productivity in marine fish. Reproductive resilience is the capacity of a population to maintain the reproductive success needed to result in long‐term population stability despite disturbances. A stock's reproductive resilience is driven by the underlying traits in its spawner‐recruit system, selected for over evolutionary timescales, and the ecological context within which it is operating. Spawner‐recruit systems are species specific, have both density‐dependent and fitness feedback loops and are made up of fixed, behavioural and ecologically variable traits. They operate over multiple temporal, spatial and biological scales, with trait diversity affecting reproductive resilience at both the population and individual (i.e. portfolio) scales. Models of spawner‐recruit systems fall within three categories: (i) two‐dimensional models (i.e. spawner and recruit); (ii) process‐based biophysical dispersal models which integrate physical and environmental processes into understanding recruitment; and (iii) complex spatially explicit integrated life cycle models. We review these models and their underlying assumptions about reproductive success vs. our emerging mechanistic understanding. We conclude with practical guidelines for integrating reproductive resilience into assessments of population connectivity and stock productivity.     

Influence of Compost Addition to Soil on the Behaviour of Herbicides

The transformations of eight herbicides (atrazine, simazine, terbutryn, pendimethalin, carbetamide, 2,4-D, metsulfuron-methyl and dimefuron) in soil after compost addition were monitored during long-term laboratory incubations. The herbicides were applied to soil, compost and soil-compost mixtures. Herbicide sorption, their kinetics of mineralisation and the extractability of residues were compared in the different treatments. Compost addition to soil generally decreased herbicide mineralisation and favoured the stabilisation of herbicide residues. A fraction of the stabilised residues remained extractable and potentially available. However, most of them were unextractable and formed bound residues. Sorption could be at the origin of a kinetically limited biodegradation, mainly for the most highly-sorbed herbicides (atrazine, simazine, terbutryn, pendimethalin and dimefuron). Compost addition had little effects on the less sorbed herbicides (carbetamide, 2,4-D and metsulfuron- methyl). © 1997 SCI.     

A Marine λ-Oligocarrageenan Inhibits Migratory and Invasive Ability of MDA-MB-231 Human Breast Cancer Cells through Actions on Heparanase Metabolism and MMP-14/MMP-2 Axis

Sugar-based molecules such as heparins or natural heparan sulfate polysaccharides have been developed and widely studied for controlling heparanase (HPSE) enzymatic activity, a key player in extracellular matrix remodelling during cancer pathogenesis. However, non-enzymatic functions of HPSE have also been described in tumour mechanisms. Given their versatile properties, we hypothesized that sugar-based inhibitors may interfere with enzymatic but also non-enzymatic HPSE activities. In this work, we assessed the effects of an original marine λ-carrageenan derived oligosaccharide (λ-CO) we previously described, along with those of its native counterpart and heparins, on cell viability, proliferation, migration, and invasion of MDA-MB-231 breast cancer cells but also of sh-MDA-MB-231 cells, in which the expression of HPSE was selectively downregulated. We observed no cytotoxic and no anti-proliferative effects of our compounds but surprisingly λ-CO was the most efficient to reduce cell migration and invasion compared with heparins, and in a HPSE-dependent manner. We provided evidence that λ-CO tightly controlled a HPSE/MMP-14/MMP-2 axis, leading to reduced MMP-2 activity. Altogether, this study highlights λ-CO as a potent HPSE “modulator” capable of reducing not only the enzymatic activity of HPSE but also the functions controlled by the HPSE levels.     

Low-Molecular-Weight Fucoidan Induces Endothelial Cell Migration via the PI3K/AKT Pathway and Modulates the Transcription of Genes Involved in Angiogenesis

Low-molecular-weight fucoidan (LMWF) is a sulfated polysaccharide extracted from brown seaweed that presents antithrombotic and pro-angiogenic properties. However, its mechanism of action is not well-characterized. Here, we studied the effects of LMWF on cell signaling and whole genome expression in human umbilical vein endothelial cells and endothelial colony forming cells. We observed that LMWF and vascular endothelial growth factor had synergistic effects on cell signaling, and more interestingly that LMWF by itself, in the absence of other growth factors, was able to trigger the activation of the PI3K/AKT pathway, which plays a crucial role in angiogenesis and vasculogenesis. We also observed that the effects of LMWF on cell migration were PI3K/AKT-dependent and that LMWF modulated the expression of genes involved at different levels of the neovessel formation process, such as cell migration and cytoskeleton organization, cell mobilization and homing. This provides a better understanding of LMWF’s mechanism of action and confirms that it could be an interesting therapeutic approach for vascular repair.     

A Necropsy Survey of Neurologic Diseases in 4,319 Horses Examined in Normandy (France) from 1986 to 2006

The frequencies of neurologic diseases and various corresponding causes were analyzed in 4,319 Norman horses examined by autopsy between 1986 and 2006. Five hundred forty-three cases of nervous system disorders were detected, or a total prevalence of 12.6%. One hundred eighty-seven of the 543 horses (34.4%) exhibited lesions of a traumatic origin affecting the skull or the vertebral column at different levels. Their frequency was less in foals younger than 1 month of age and higher in horses aged 6 months to 2 years. Eighty-three cases of cervical vertebral compressive myelopathy (CVCM) (15.3%) were identified. Males and geldings were more often affected than females. CVCM was diagnosed mostly in animals aged 6 months to 2 years. Horses affected with lesions in the mid-cervical region (region C3–C5) were significantly younger than those exhibiting more caudal lesions (region C5–C7). Neonatal maladjustment syndrome was diagnosed in 62 foals younger than 3.5 days (4.8% of the causes of death between birth and 1 month) by using clinical or lesional criteria. The prevalence was higher in Thoroughbreds as well as in the miscellaneous breed category and less in French Standardbreds. Bacterial meningoencephalomyelitis and meningitis represented 9.6% of nervous system disorders (52 cases) and most often affected foals aged 1 to 6 months. The main bacteria identified were beta-hemolytic Streptococci , Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, and Actinobacillus sp. The other causes diagnosed were, in decreasing order of frequency: grass sickness or equine dysautonomia (6.3% of neurologic diseases), hepatic encephalopathy syndrome (5.2%), septic vertebral arthritis or osteitis mainly caused by Rhodococcus equi (2.6%), congenital defects of the nervous system (2.4%), equine herpesvirus 1 myeloencephalopathy (2.2%), botulism (2.2%), malformations of the vertebral column other than CVCM (2%), and neighboring polyneuritis associated with guttural pouch mycosis (1.5%).     

Chlamydial infections in duck farms associated with human cases of psittacosis in France

Five severe cases of psittacosis in individuals associated with duck farms were notified in France between January and March 2006. Diagnostic examination included serology and/or molecular detection by PCR from respiratory samples. As a consequence, we investigated all duck flocks (n=11) that were housed in the three farms where human infections occurred. While serology by complement fixation test was negative for all samples, cloacal and/or tracheal chlamydial excretion was detected by PCR in all three units. Notably, one duck flock was tested strongly positive in 2 of the 3 affected farms, and Chlamydophila (C.) psittaci strains were isolated from cloacal and/or tracheal swab samples from both farms. Human samples and duck isolates exhibited the same PCR-RFLP restriction pattern, which appeared to be an intermediate between genotypes A and B. Analysis of ompA gene sequences and comparison to those of the type strains showed that the isolates could not be strictly assigned to any of the generally accepted genotypes of C. psittaci. Further analysis by MLVA of the PCR-positive human samples revealed two distinct patterns, which were related to previously isolated C. psittaci duck strains.     

Prioritizing action for recovery and conservation of marine species: a case study based on species of conservation importance around England

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Examining the Effect of Billboards in Shaping the Great Wolf Debate of the American West

Large carnivore reintroductions have become commonplace in modern conservation. Despite the benefits of such initiatives, conflict with humans can jeopardize their success. Reintroductions of grey wolves (Canis lupus) in the American West are particularly polarizing, and opposing views are often popularized through visual media. We examined public billboards, both for and against wolves, in eastern Washington State. We used social science concepts—framing, affect, and the psychology of advertising—to assess the billboards’ role in the wolf debate. We analyzed visual imagery, traced frames in newspaper articles, and conducted interviews with local stakeholders. Our results showed that the billboards attracted attention to the issue and increased tension within the debate. However, they were limited in their ability to stimulate engagement due to a discrepancy between their structure and intended impacts. Results suggested the necessity for careful selection of campaign techniques and focused alignment of imagery and frames.