New Antidiabetic Targets of α-Glucosidase Inhibitory Peptides,SVPA, SEPA,STYV and STY: Inhibitory Effects on Dipeptidyl Peptidase-IV and Lipid Accumulation in 3T3-L1 Differentiated Adipocytes with Scavenging Activities Against Methylglyoxal and Reactive Oxygen Species

Type 2 diabetes mellitus (T2DM) is a multifactorial disease that requires multiple therapeutic strategies for its management. Bioactive peptides with multiple anti-diabetic targets are attractive therapeutic molecules. The present study was conducted to identify additional anti-diabetic targets of α-glucosidase inhibitory peptides, SVPA, SEPA, STYV, and STY. The α-glucosidase inhibitory activity of the peptides was in the order STYV?>?STY?>?SEPA?>?SVPA while molecular docking against human dipeptidyl peptidase IV (DPP-IV) showed that SVPA had the best binding affinity. In contrast, in vitro studies indicated that SEPA had a significantly higher (P?<?0.05) DPP-IV inhibitory activity (IC₅₀?=?5.78?±?0.19 mM) than other peptides. SVPA and SEPA showed mixed inhibition pattern while STYV and STY were uncompetitive inhibitors of the enzyme. IPI (diprotin A), STYV and STY were not cytotoxic while SEPA displayed some cytotoxicity. In differentiated 3T3-L1 adipocytes, SVPA and STYV were found to induce a significant (P?<?0.05) decrease in intracytoplasmic lipid accumulation when added during the differentiation process while STY, GSH and IPI caused significant reduction (P?<?0.05) in the lipid accumulation when added after the differentiation. The SVPA, SEPA and STYV were better scavengers of methylglyoxal than STY but STYV had the best scavenging activities toward reactive oxygen species and nitric oxide. It was concluded that the four α-glucosidase inhibitory peptides including IPI have multiple targets against type T2DM but, overall, of the four peptides evaluated, STYV tends to have better potential for application as a multifunctional anti-diabetic peptide.

     

Vagrant Antarctic pinnipeds at Gough Island

Opportunistic sightings of Antarctic fur seals Arctocephalus gazella and a leopard seal Hydrurga leptonyx at Gough Island (40°20′S, 09°54′W) in the South Atlantic Ocean represent the northernmost island records for vagrant Antarctic fur seals, and only the second for a vagrant leopard seal at Gough Island. Some ten different individual Antarctic fur seals were sighted on a single day, up to seven on a single beach. An overall total of 18 individuals were recorded over a 7-week period in October/November 2005, before the onset of the breeding (pupping) season of the resident population of Subantarctic fur seals Arctocephalus tropicalis. Most were immature, male and mostly in good condition (n = 11, 61%); one mature male and six putative females were also present. All had departed after 23 November, although only a fraction of the available beaches was searched.     

A lifetime at depth: vertical distribution of southern elephant seals in the water column

Although numerous studies have addressed the migration and dive behaviour of southern elephant seals (Mirounga leonina), questions remain about their habitat use in the marine environment. We report on the vertical use of the water column in the species and the potential lifetime implications for southern elephant seals from Marion Island. Long-term mark-resight data were used to complement vertical habitat use for 35 known individuals tagged with satellite-relay data loggers, resulting in cumulative depth use extrapolated for each individual over its estimated lifespan. Seals spent on average 77.59% of their lives diving at sea, 7.06% at the sea surface, and 15.35% hauled out on land. Some segregation was observed in maximum dive depths and depth use between male and female animals—males evidently being physiologically more capable of exploiting increased depths. Females and males spent 86.98 and 80.89% of their lives at sea, respectively. While at sea, all animals spent more time between 300 and 400 m depth, than any other depth category. Males and females spent comparable percentages of their lifetimes below 100 m depth (males: 65.54%; females: 68.92%), though males spent 8.98% of their lives at depths in excess of 700 m, compared to females’ 1.84% at such depths. Adult males often performed benthic dives in excess of 2,000 m, including the deepest known recorded dive of any air-breathing vertebrate (>2,133 m). Our results provide a close approximation of vertical habitat use by southern elephant seals, extrapolated over their lifespans, and we discuss some physiological and developmental implications of their variable depth use.     

Yeast flocculation and its biotechnological relevance

Adhesion properties of microorganisms are crucial for many essential biological processes such as sexual reproduction, tissue or substrate invasion, biofilm formation and others. Most, if not all microbial adhesion phenotypes are controlled by factors such as nutrient availability or the presence of pheromones. One particular form of controlled cellular adhesion that occurs in liquid environments is a process of asexual aggregation of cells which is also referred to as flocculation. This process has been the subject of significant scientific and biotechnological interest because of its relevance for many industrial fermentation processes. Specifically adjusted flocculation properties of industrial microorganisms could indeed lead to significant improvements in the processing of biotechnological fermentation products such as foods, biofuels and industrially produced peptides. This review briefly summarises our current scientific knowledge on the regulation of flocculation-related phenotypes, their importance for different biotechnological industries, and possible future applications for microorganisms with improved flocculation properties.     

Leucistic Antarctic fur seals at Bouvetøya

One leucistic and one partially leucistic Antarctic fur seal Arctocephalus gazella were seen at Bouvetøya during the 1996/97 austral summer. Both likely came from South Georgia, where this colour morph is common. No individuals of this colour morph were sighted during three subsequent expeditions to Bouvetøya. The prevalence of this colour morph in the abundant populations of the Scotia Arc may be due to founder effect, as at least one leucistic animal was present at South Georgia when the Antarctic fur seal was close to extinction.     

Hypertrophic response of Duchenne and limb-girdle muscular dystrophies is associated with activation of Akt pathway

Dystrophic muscle undergoes repeated cycles of degeneration/regeneration, characterized by the presence of hypertrophic fibers. In order to elucidate the signaling pathways that govern these events, we investigated Akt activation in normal and dystrophic muscle. Akt is activated in neonatal muscle and in actively dividing myoblasts, supporting a developmental role for Akt signaling. Akt activation was detected at very early, prenecrotic stages of disease pathogenesis, and maximal activation was observed during peak stages of muscle hypertrophy. Duchenne muscular dystrophy patients exhibit a similar pattern of Akt activation. Mice with sarcoglycan-deficient muscular dystrophy possess more severe muscle pathology and display elevated Akt signaling. However, the highest levels of Akt activation were found in dystrophin-utrophin-deficient muscle with very advanced dystrophy. We propose that Akt may serve as an early biomarker of disease and that Akt activation mediates hypertrophy in muscular dystrophy. Current investigations are focused on introducing constitutively active and dominant-negative Akt into prenecrotic mdx mice to determine how early modification of Akt activity influences disease pathogenesis.