Redox cycling induces spermptosis and necrosis in stallion spermatozoa while the hydroxyl radical (OH•) only induces spermptosis

Oxidative stress is a major factor explaining sperm dysfunction of spermatozoa surviving freezing and thawing and is also considered a major inducer of a special form of apoptosis, visible after thawing, in cryopreserved spermatozoa. To obtain further insights into the link between oxidative stress and the induction of apoptotic changes, stallion spermatozoa were induced to oxidative stress through redox cycling after exposure to 2‐methyl‐1,4‐naphthoquinone (menadione), or hydroxyl radical formation after FeSO₄ exposure. Either exposure induced significant increases (p < 0.05) in two markers of lipid peroxidation: 8‐iso‐PGF_2α and 4‐hydroxynonenal (4‐HNE). While both treatments induced changes indicative of spermptosis (caspase‐3 activation and decreased mitochondrial membrane potential) (p < 0.01), menadione induced sperm necrosis and a dramatic reduction in motility and thiol content in stallion spermatozoa. Thus, we provided evidence that oxidative stress underlies spermptosis, and thiol content is a key factor for stallion sperm function.     

Mechanistic target of rapamycin is activated in bovine granulosa cells after LH surge but is not essential for ovulation

The LH surge induces functional and morphological changes in granulosa cells. Mechanistic target of rapamycin (mTOR) is an integrator of signalling pathways in multiple cell types. We hypothesized that mTOR kinase activity integrates and modulates molecular pathways induced by LH in granulosa cells during the preovulatory period. Cows were ovariectomized and granulosa cells collected at 0, 3, 6, 12 and 24 hr after GnRH injection. While RHEB mRNA levels increased at 3 and 6 hr, returning to basal levels by 12 hr after GnRH treatment, RHOA mRNA levels increased at 6 hr and remained high thereafter. Western blot analyses revealed increased S6K phosphorylation at 3 and 6 hr after GnRH injection. Similarly, mRNA levels of ERK1/2, STAR and EGR‐1 were higher 3 hr after GnRH treatment. Rapamycin treatment inhibited mTOR activity and increased AKT activity, but did not alter ERK1/2 phosphorylation and EGR1 protein levels in cultured bovine granulosa cells. Rapamycin also inhibited LH‐induced increase in EREG mRNA abundance in granulosa cells in vitro. However, intrafollicular injection of rapamycin did not suppress ovulation. These findings suggest that mTOR is involved in the control of EREG expression in cattle, which may be triggered by LH surge stimulating RHEB and S6K activity.     

Development of a Standardized Modular System for Experimental Coral Culture

The increasing interest in coral culture for reef restoration, biotechnological applications, and to supply the marine aquarium trade has prompted researchers to optimize coral culture protocols, with emphasis on ex situ production. However, the diversity of experimental systems employed to investigate ex situ coral production may be a bottleneck to the advance of the state of the art, as it impairs reliable comparisons between experiments, as well as the replication and optimization of culture protocols. This study presents a versatile modular culture system for experimental coral production ex situ, assembled using materials and equipments available from suppliers all over the world and thus allowing researchers worldwide to truly replicate experimental setups. The validation of the modular culture system was performed using the soft coral, Sarcophyton cf. glaucum, as a model organism. The validation experiment tested the effect of different light spectra on the photosynthetic performance, symbiont density, chlorophyll and carotenoid pigments concentration, survival, and growth of coral fragments. The validation experiment confirmed the potential of this modular culture system, which ultimately enables researchers to perform direct comparisons among experiments, and more efficiently contribute to advance ex situ coral aquaculture.     

Drought Tolerance Screening Under Controlled Conditions Predicts Ranking of Water‐Limited Yield of Field‐Grown Soybean Genotypes

Drought is a major limitation to crop yields worldwide. Screening for soybean yield under water deficit is often a bottleneck in breeding programmes. We assessed the validity of a standardized drought tolerance screening method to predict water‐limited field performance of soybean in NW Argentina. First, to determine the phenological period when yield of glasshouse‐grown plants was more sensitive to water deficit, we applied treatments during 21 days in V₇, R₃ or R₅ stages, being the period from R₅ to R₆ the most critical for yield. Afterwards, two glasshouse experiments were carried out to quantify the tolerance of either eight or four genotypes, respectively, by applying a controlled water deficit of constant intensity during the critical period. Finally, yield data obtained in field trials in Argentina across several locations and seasons classified according to rainfall were analysed. Drought Susceptibility Index was calculated for each experiment and for field data, and rankings of tolerance were similar in all cases. This standardized method, which can be automated for high‐throughput phenotyping, could represent a useful tool in breeding programmes for identifying soybean cultivars with improved performance under drought conditions.     

Promotive effects of long-term fertilization on growth of tissue culture-derived Hypericum polyanthemum plants during acclimatization

The effect of long-term fertilization supply on biomass yield and secondary metabolites accumulation was assessed in vegetative and reproductive parts of acclimatized field grown plants of Hypericum polyanthemum, an endemic species of southern Brazil. Fertilization caused positive responses in plant growth with biomass increment of vegetative and reproductive parts, proportional to the MS solution concentration (25%, 50% and 100%), whereas the chemical analyses indicated that the supply of fertilization solution did not alter the concentration of 6-isobutyryl-5,7-dimethoxy-2,2-dimethyl-benzopyran (HP1), 7-hydroxy-6-isobutyryl-5-methoxy-2,2-dimethyl-benzopyran (HP2), uliginosin B as well as total phenolic compounds (TPCs), and increased the accumulation of 5-hydroxy-6-isobutyryl-7-methoxy-2,2-dimethyl-benzopyran (HP3) in all fertilization regimes.     

Dietary Protein Requirement of Juvenile Cachara Catfish,Pseudoplatystoma reticulatum

Cachara, Pseudoplatystoma reticulatum, is a high commercial value carnivorous catfish in Brazil, but whose dietary protein requirement is still unknown. Aiming to determine this requirement, groups of 15 juveniles (16.08 ± 1.13 g) were fed isoenergetic diets (4600 kcal/kg gross energy) with increasing levels of crude protein (30, 35, 40, 45, 50, and 55%). After 60 d, regression analysis revealed a quadratic effect (P < 0.05) of increasing dietary crude protein concentration on growth variables. The highest weight gain and specific growth rate as well as the best feed conversion were shown by fish fed the 50% crude‐protein diet. Similarly, protease activities were significantly higher (P < 0.05) in fish fed 50% crude protein. However, the highest protein retention was observed in fish fed the 45% crude‐protein diet. Protein and dry matter digestibilities did not differ (P > 0.05) for diets containing 40, 45, or 50% crude protein. Therefore, based on weight gain and at a dietary energy concentration of 4600 kcal/kg, the estimated protein requirement for juvenile cachara between 16 and 85 g is 49.25% crude protein. This is equivalent to 44.79% digestible protein and a gross energy to digestible protein ratio of 10.27 kcal/g.     

Apparent Protein and Energy Digestibility and Amino Acid Availability of Corn and Co‐products in Extruded Diets for Nile Tilapia,Oreochromis niloticus

We assessed the nutritional value of corn in extruded diets for Nile tilapia, Oreochromis niloticus, by determining the apparent digestibility coefficients of dry matter, crude protein, and gross energy, and by measuring the apparent availability coefficients (AACs) of essential and non‐essential amino acids (AAs) in several corn‐based diets. We fed 180 juvenile Nile tilapia a reference diet containing 325.8 g/kg crude protein and 4613 kcal/kg gross energy or a test diet containing a 70:30 mixture of the reference diet and a test ingredient (whole corn, corn germ, corn germ meal, corn gluten feed, or corn gluten meal). The apparent digestibility coefficients ranged from 56.3 to 96.6% (dry matter), 89.4 to 96.8% (crude protein), and 59.0 to 95.4% (gross energy). The AACs of all AAs exceeded 80% for all diets and were >90% for corn gluten meal. All ingredients showed high levels of apparent digestibility for crude protein and high AACs of AAs. Diets based on whole corn or corn gluten meal showed higher digestibility values for dry matter and gross energy, suggesting that they are preferable choices for Nile tilapia.