Effects of no‐take area size and age of marine protected areas on fisheries yields: a meta‐analytical approach

Marine protected areas (MPAs) are often promoted as tools for biodiversity conservation as well as for fisheries management. Despite increasing evidence of their usefulness, questions remain regarding the optimal design of MPAs, in particular concerning their function as fisheries management tools, for which empirical studies are still lacking. Using 28 data sets from seven MPAs in Southern Europe, we developed a meta‐analytical approach to investigate the effects of protection on adjacent fisheries and asking how these effects are influenced by MPA size and age. Southern European MPAs showed clear effects on the surrounding fisheries, on the ‘catch per unit effort’ (CPUE) of target species, but especially on the CPUE of the marketable catch. These effects depended on the time of protection and on the size of the no‐take area. CPUE of both target species and the marketable catch increased gradually by 2–4% per year over a long time period (at least 30 years). The influence of the size of the no‐take area appeared to be more complex. The catch rates of the entire fishery in and around the MPA were higher when the no‐take areas were smaller. Conversely, catch rates of selected fisheries that were expected to benefit most from protection increased when the no‐take area was larger. Our results emphasize the importance of MPA size on its export functions and suggest that an adequate, often extended, time frame be used for the management and the evaluation of effectiveness of MPAs.     

Cryopreservation effects on the sperm quality of cachama blanca Piaractus brachypomus (Cuvier 1818)

The effects of straws volume, cryoprotectants and thawing temperatures were evaluated on the sperm quality of cachama blanca Piaractus brachypomus (Cuvier), an important Colombian fish species. Sexually mature fish were induced to ovulation or spermiation with a carp pituitary extract. A pool of suitable sperm samples was diluted in glucose, egg yolk, dimethyl sulphoxide (DMSO‐10%), methanol (MET‐10%) or ethylene glycol (ETG‐5%) and packed in 0.5, 2.5 or 5.0 mL straws and frozen in nitrogen vapour. The thawing process was performed in a 35 or an 80 °C water bath. The fertility was evaluated after 6 h post fertilization. The highest motility percentage (33 ± 3%) was observed with sperm cryopreserved with DMSO, packed in 5 mL straws and thawed at 35 °C. The treatments with DMSO and MET packed in 0.5 and 5.0 mL straws and thawed at 35 °C showed the highest fertility (higher than 71%) and the lowest fertility was obtained with MET‐2.5 mL (9 ± 5%). In all the treatments, a significant decrease in the sperm quality was observed at 80 °C. Sperm cryopreserved with DMSO‐10% or MET‐10%, packed in 2.5 or 5.0 mL straws are suitable to achieve acceptable fertilization and to fertilize high amounts of eggs.     

Genetic characterization of a collection of chayote, <Emphasis Type="Italic">Sechium edule</Emphasis> (Jacq.) Swartz,in Costa Rica by using isozyme markers

We established protocols for the analysis of genetic diversity in chayote (Sechium edule) by using isozyme markers, thereby determining the level of genetic diversity present in 42 accessions of chayote from Costa Rica. We obtained clear and reproducible zymograms for eight enzyme staining systems: PGM, 6-PGD, PGI, IDH, MDH, SOD, SKD, and EST, and were able to score 14 putative loci. Eight of the 14 loci examined were polymorphic. We found 35 distinct multilocus genotypes among these accessions. Five of these multilocus genotypes were homozygous for all loci. In addition, our data also revealed that most of the multilocus genotypes (24) were heterozygous for only one of the eight loci, and the rest were heterozygous for two or three loci (9 and 4 accessions, respectively). Seven multilocus genotypes were found in two different accessions. Dice similarity coefficient was used to study the relationship between accessions. This analysis, based on the presence and absence of alleles, revealed that accessions collected in the same location seldom shared the same multilocus genotype. The value of isozyme polymorphisms as tools to continue studies on the characterization of chayote is discussed.     

Ripening-related defense proteins in Annona fruit

In order to obtain a better understanding of the active defense strategy of cherimoya (Annona cherimola Mill.) fruit, hydrolytic and antifungal activity, as well as expression of proteins functionally and immunogenically related to the pathogenesis-related proteins chitinase (PR-Q) and 1,3-β-glucanase (PR-2), were estimated in fruit at different ripening stages. Increase in expression of the 27 kDa constitutive chitinase and the induction of two new proteins, a 26 kDa chitinase and a 51 kDa 1,3-β-glucanase were associated with enhanced in vitro hydrolytic and antifungal activity of the acidic protein extract in ripe fruit. Ripening modified the expression of constitutive basic isoenzymes, with a sharp decrease in both relative accumulation and hydrolytic activity. Likewise, a new basic 33 kDa chitinase was induced in the over-ripe fruit, concomitant with accumulation of a basic constitutive 76 kDa 1,3-β-glucanase. At this stage, the basic protein extract modified in vitro growth inhibition of Botrytis cinerea. Short-term high CO₂ treatment delayed fruit ripening and maintained a similar distribution of activity and isoenzymatic pattern in both protein fractions to that in unripe fruit. These results indicate that the changes in the pattern of defense proteins and hydrolytic activity in cherimoyas appear to be associated with ripening. Moreover, unlike the constitutively expressed isoenzymes, only the transitorily induced chitinases and 1,3-β-glucanases were associated with an active defense-related response.     

Bioprospection of Microalgae and Cyanobacteria as Biocontrol Agents Against Vibrio campbellii and Their Use in White Shrimp Litopenaeus vannamei Culture

Vibrio spp. are the most common and harmful shrimp pathogenic bacteria; however, microalgae and cyanobacteria have the ability to produce antimicrobial substances against these species. In this study, the organic and aqueous extracts of 28 species of marine microalgae and cyanobacteria were screened against Vibrio campbellii M1. Two of these phytoplankton species with antibacterial activity in aqueous extracts (Dunaliella tertiolecta and Skeletonema costatum) and nontoxic to brine shrimp Artemia franciscana nauplii were used to evaluate their anti‐Vibrio effect when used as green‐water cultures in Vibrio‐challenged white shrimp Litopenaeus vannamei cultures. No differences in mortality of juvenile L. vannamei were observed between treatments tested, suggesting that the pathogenicity of V. campbellii could be related to the growth stage of shrimp. The proximal composition of D. tertiolecta and S. costatum was in the recommended range for penaeid shrimp nutrition, allowing shrimp supplemented with these microalgae to have significantly greater total length and weight than control shrimp. Shrimp supplemented with S. costatum presented the highest values of organic mass (11.48 mg/organism) and growth rate (0.31 mg/d) in comparison to D. tertiolecta. These results indicate that microalgae are not only capable of producing antibacterial compounds against Vibrio but can also help shrimp nutrition.     

Insulin binding to bovine mammary membranes: comparison of microsomes versus smooth membranes

The study was undertaken to determine if membrane preparations of bovine mammary tissue bound insulin. If binding occurred, it was also the intent to compare binding kinetics between microsomes and smooth membranes. Insulin binding to bovine mammary membranes attained equilibrium, was saturable and was specific for insulin. Additional studies showed binding to be pH sensitive and maximal at 10 mM calcium. Binding affinity of insulin to microsomes and smooth membranes was similar, with the exception that smooth membranes bound 1.8 times more insulin per unit of membrane protein than microsomes. Two different methods were used to generate data for kinetic analysis of the insulin-receptor interaction in microsomes. Competitive binding assays (.6 ng [125I]insulin plus 0 to 100 ng insulin) indicated the presence of two binding sites with dissociation constants (Kd) of .32 and 15.8 nM. Direct titration of microsomes with [125I]insulin (.02 to 10 ng/ml) revealed two binding sites with Kd of .017 and .31 nM. The affinity of the second binding site measured by the competitive binding assay method (Kd of 15.8 nM) is low and therefore may not be of physiological importance for insulin action. Insulin appears to bind to two high-affinity receptor sites in bovine mammary microsomes with Kds of .017 nM and .32 nM. These findings show that bovine mammary tissue contains receptors for insulin. In addition, isolation of smooth membranes from microsomes enriches the number of insulin receptors per unit of membrane protein without altering their binding characteristics.