Growth-dependent survival mechanisms during the early life of a temperate seabass (Lateolabrax japonicus): field test of the ‘growth–mortality’ hypothesis

Three concepts based on size, time and growth rate are contained in the functional mechanisms of the ‘growth–mortality’ hypothesis, and are known as the ‘bigger is better’, ‘stage duration’ and ‘growth-selective predation’ hypotheses, respectively. Although it is sufficiently documented in fishes that faster growing and bigger larvae selectively survive, synergistic operation of the three components of the ‘growth–mortality’ hypothesis within a species have received little attention. In this study, we have tested the components of the ‘growth–mortality’ hypothesis based on the growth characteristics of original population (OP) and survivors (SV) of Japanese seabass (JSB) Lateolabrax japonicus. Larval and juvenile JSB were repeatedly sampled from the Tango Sea in 2007 and 2008. Otoliths from larvae and juveniles were analyzed to produce back-calculated daily records of size-at-age and growth rate, and were compared between OP and SV. Selective survival for fast-growing and bigger larvae was evident, and our results strongly support the ‘bigger is better’ hypothesis as well as the ‘growth-selective predation’ hypothesis. Growth rates of the individuals that metamorphosed into juveniles had significantly faster growth rates than non-metamorphosing larvae older than 48 days, the minimum age for metamorphosis, suggesting a clear relationship between growth rates and the timing of metamorphosis. On average, SV completed the larval stage ∼13 days earlier than those of OP, supporting the ‘stage duration’ hypothesis. Thus, SV of JSB exhibited traits consistent with all aspects of the ‘growth–mortality’ hypothesis: faster growth, bigger size-at-age, and shorter larval stage duration (LSD), i.e., larvae with faster growth, bigger size-at-age and a shorter LSD selectively survived the larval period. Although maternal influence on growth and survival was evident, factors that regulate growth–mortality mechanisms remain to be explored for JSB.     

Effects of a meal rich in 1,3-diacylglycerol on postprandial cardiovascular risk factors and the glucose-dependent insulinotropic polypeptide in subjects with high fasting triacylglycerol concentrations

It was previously reported that compared to triacylglycerol (TAG) oil, diacylglycerol (DAG) oil improves postprandial lipid response. However, the effects of DAG oil on postprandial hyperglycemia and incretin response have not yet been determined. In this study, the effects of DAG oil on both postprandial hyperlipidemia and hyperglycemia and the response to the glucose-dependent insulinotropic polypeptide (GIP) were studied. This randomized, double-blind, crossover study analyzed data for 41 individuals with high fasting triacylglycerol concentrations. The subjects ingested test meals (30.3 g of protein, 18.6 g of fat, and 50.1 g of carbohydrate) containing 10 g of DAG oil (DAG meal) or TAG oil (TAG meal) after fasting for at least 12 h. Blood samples were collected prior to and 0.5, 2, 3, 4, and 6 h after ingestion of the test meal. Postprandial TAG concentrations were significantly lower after the DAG meal compared with the TAG meal. Postprandial TAG, insulin, and GIP concentrations were significantly lower after the DAG meal compared with the TAG meal in 26 subjects with fasting serum TAG levels between 1.36 and 2.83 mmol/L. DAG-oil-based meals, as a replacement for TAG oil, may provide cardiovascular benefits in high-risk individuals by limiting lipid and insulin excursions.     

Genetic diagnosis of band 3 deficiency and sexing in bovine preimplantation embryos

Band 3 deficiency with hereditary spherocytosis and hemolytic anemia in Japanese black cattle, band 3(Bov.Yamagata), is caused by a total lack of band 3 protein with an autosomal dominant inheritance. Genotyping for band 3 deficiency and sexing were successfully achieved in biopsied embryo cells with efficiencies of 98.4% and 97.4%, respectively. Transfer of the embryo that was determined as homozygous for the mutant allele into a recipient cow resulted in the production of a fetus exhibiting the genotype and red cell phenotypes characteristic of band 3(Bov.Yamagata). These results demonstrate that our procedure is reliable and applicable to produce animals free from or homozygous for the mutant allele by breeding carrier animals.     

Production of galacto-manno-oligosaccharides from guar gum by beta-mannanase from Penicillium oxalicum SO

Beta-mannanase from Penicillium oxalicum SO efficiently hydrolyzed guar galactomannan to galacto-manno-oligosaccharides. Gel filtration estimated the molecular weight of the beta-mannanase as 35 000 and SDS-PAGE as 29 000. The optimum pH was around 5 while a stable pH was reached in the range of 3-6. Optimum temperature was around 60 degrees C at pH 5, while under 60 degrees C activity was stable. HPLC analysis detected oligosaccharides with degrees of polymerization (DP) of 2 to 7 and 2 to 6 released on hydrolysis of guar and locust bean gums, respectively; about 92% of the released sugars were oligosaccharides. In analysis of the sugar distribution on MALDI-TOF-MS, major products of DP 6 and 7 and DP 5 and 6 were confirmed in hydrolysates of guar gum and locust bean gum, respectively. One of the main oligosaccharides released from guar gum, with DP 7, had a high galactose content (Gal/Man = 0.76) and corresponded to a blockwise galactose-substituted mannan type in galactomannan.     

Nitrogen, phosphorus and potassium utilization and their cycling in a beef-forage production system

The objective of this study was to quantify nitrogen (N), phosphorus (P) and potassium (K) utilization and their cycling in a beef-forage production system. A survey was conducted at the Kyoto University experimental farm in Kyoto Prefecture, Japan, and included 9.5 ha of meadow and about 160 head of beef cattle. Forages cultivated on the meadow were ensiled and offered to breeding cows. The whole farm was regarded as a beef-forage production system. The system consisted of three components: animals, manure and soil/crop. Nutrient inputs, flows through the soil-plant-animal pathway and outputs were quantified for 2 periods for the whole farm. Nutrient utilization was evaluated by nutrient balances, utilization efficiencies (ratio of nutrient export to nutrient input) and cycling index. The average nutrient balances of N, P and K for the whole farm (kg/year/ha) were 435.7, 136.3, and 262.8, and the average nutrient utilization efficiencies were 0.08, 0.06, and 0.01, respectively. The characteristics of nutrient balances and utilization efficiencies for each component differed among the nutrients. The average cycling indices for N, P and K were 0.19, 0.17 and 0.49, respectively. This study illustrates the importance of internal nutrient cycling for improving nutrient utilization in beef production systems.     

The dorsal aorta initiates a molecular cascade that instructs sympatho-adrenal specification

The autonomic nervous system, which includes the sympathetic neurons and adrenal medulla, originates from the neural crest. Combining avian blood vessel-specific gene manipulation and mouse genetics, we addressed a long-standing question of how neural crest cells (NCCs) generate sympathetic and medullary lineages during embryogenesis. We found that the dorsal aorta acts as a morphogenetic signaling center that coordinates NCC migration and cell lineage segregation. Bone morphogenetic proteins (BMPs) produced by the dorsal aorta are critical for the production of the chemokine stromal cell-derived factor-1 (SDF -1) and Neuregulin 1 in the para-aortic region, which act as chemoattractants for early migration. Later, BMP signaling is directly involved in the sympatho-medullary segregation. This study provides insights into the complex developmental signaling cascade that instructs one of the earliest events of neurovascular interactions guiding embryonic development.