The effect of temperature and crowding on midgut amylolytic activity in Tenebrio molitor adults

The effect of two constant temperatures (23°C and 28°C), mixed group (5 + 5), and isolation on the midgut amylolytic activity during adult development of Tenebrio molitor has been investigated in vitro. Higher temperatures (28°C) and mixed groups stimulate the rate of midgut amylolytic activity. After attaining the maximal level, the amylolytic activity shows fluctuations. The possible role of hormones and primer pheromones in the control of the midgut amylolytic activity in T. molitor adults is discussed.     

No mate preference associated with the supergene controlling social organization in Alpine silver ants

Disassortative mating is a powerful mechanism stabilizing polymorphisms at sex chromosomes and other supergenes. The Alpine silver ant, Formica selysi, has two forms of social organization—single‐queen and multiple‐queen colonies—determined by alternate haplotypes at a large supergene. Here, we explore whether mate preference contributes to the maintenance of the genetic polymorphism at the social supergene. With mate choice experiments, we found that females and males mated randomly with respect to social form. Moreover, queens were able to produce offspring irrespective of whether they had mated with a male from the same or the alternative social form. Yet, females originating from single‐queen colonies were more fertile, suggesting that they may be more successful at independent colony founding. We conclude that the pattern of asymmetric assortative mating documented from mature F. selysi colonies in the field is not caused by mate preferences or major genetic incompatibilities between social forms. More generally, we found no evidence that disassortative mate preference contributes to the maintenance of polymorphism at this supergene controlling ant social organization.     

Metabolic response of cerambycid beetle (Morimus funereus) larvae to starvation and food quality

The response of xylophagous Morimus funereus larvae to a direct change of diet demonstrated that the larvae from nutrient-poor substrates, e.g. oak, are very sensitive to such a change. Depending on dietary protein quality and quantity, an increase of proteolytic activity, i.e. an intensified protein metabolism accompanied by changes in body mass gain, was observed. At the same time, amylolytic activity was usually decreased. In the larvae reared on Robert's diet, sensitivity to the switch in diet was lower at the level of proteolytic enzymes that remained at the control level, while amylolytic activity was elevated. If the switch to a new diet was preceded by 7-day-starvation that disturbed nutritional homeostasis, the response of the larvae was similar to that recorded upon a direct switch only after short-term feeding (24 h) upon starvation. Differences in the response to changes in the diet of the larvae from nature, those reared under laboratory conditions and those of different physiological status could be ascribed to plasticity in the expression of the genes coding for proteases and their isoenzymes, as well as to the multi-functionality of some neurosecretory neurons, synthetic products that participate in the regulation of digestive enzyme activities.     

Genetic diversity of 15 STR loci in a population of Montenegro

Genetic diversity and forensic parameters based on 15AmpFlSTR Identifiler short tandem repeat (STR) loci (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818 and FGA) were evaluated in a sample of 101 unrelated, autochthonous adults from Montenegro. After applying Bonferroni correction, the agreement with Hardy-Weinberg equilibrium (HWE) was confirmed for all loci with the exception of D5S818 (chi2 test) and D21S11 (exact test). The combined power of discrimination (PD) and the combined power of exclusion (PE) for the 15 studied loci were 0.9999999999999999844 and 0.99999382, respectively. According to measures of within-population genetic diversity, D2S1338, D18S51 and FGA may be considered as the most variable and most informative markers for forensic testing and population genetic analyses out of the 15 analysed loci in a population of Montenegro. D5S818 showed to be the least variable and together with TPOX, the least informative. Interpopulation comparisons were carried out and levels of genetic differentiation between population of Montenegro and five South-eastern European populations (Kosovo Albanians, Serbians from Vojvodina province, Macedonians, Bosnians and Croatians) were evaluated. The most differentiated population in relation to Montenegro is a population of Kosovo Albanians as suggested by both AMOVA and coefficients of genetic differentiation (F(ST) and R(ST)).     

Purification and properties of midgut alpha-amylase isolated from Morimus funereus (Coleoptera: Cerambycidae) larvae

Using soluble starch as a substrate five isoforms of alpha-amylase were identified in a crude extract of Morimus funereus larvae. The main alpha-amylase (termed AMF-3) was purified by gel filtration chromatography and anion exchange chromatography to obtain a single band on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Its enzymatic purity was confirmed by an in-gel activity assay after SDS-PAGE. The purity of AMF-3 was increased 112-fold with a 15.4% yield. AMF-3 had apparent molecular masses of 33 and 31 kDa when analysed using SDS-PAGE and Superdex 75 FPLC gel filtration chromatography, respectively and a calculated isoelectric point of 3.2. Purified AMF-3 showed maximal activity at pH 5.2 and had an optimum activity temperature of 45 degrees C. AMF-3 retained over 90% of its maximum activity at temperatures from 45 to 60 degrees C. AMF-3 exhibited a high affinity towards soluble starch with a K(m) value of 0.43 mg/mL. Maximal AMF-3 activity was achieved in the presence of 0.1 mM CaCl(2), while at higher concentrations its activity decreased. AMF-3 activity increased with increasing NaCl concentration. AMF-3 activity was significantly inhibited by alpha-amylase wheat inhibitor. Using a number of raw starch substrates maximum AMF-3 activity was achieved with horse-radish starch, in contrast to undetectable activity towards potato starch.     

Purification and properties of major midgut leucyl aminopeptidase of Morimus funereus (Coleoptera, Cerambycidae) larvae

The major leucyl aminopeptidase (LAP) from the midgut of Morimus funereus larvae was purified and characterised. Specific LAP activity was increased 292-fold by purification of the crude midgut extract. The purified enzyme had a pH optimum of 7.5 (optimum pH range 7.0-8.5) and preferentially hydrolysed p-nitroanilides containing hydrophobic amino acids in the active site, with the highest V(max)/K(M) ratio for leucine-p-nitroanilide (LpNA). Among a number of inhibitors tested, the most efficient were 1,10-phenanthroline having a K(i) value of 0.12 mM and cysteine with K(i) value of 0.31 mM, while EGTA stimulated LAP activity. Zn(2+), Mg(2+) and Mn(2+) all showed bi-modal effects on LAP activity (activated at low concentrations and inhibited at high concentrations). The purified LAP (after gel filtration on Superose 6 column) had molecular mass of 400 kDa with an isoelectric point of 6.2. Sodium dodecylsulphate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed one band of 67 kDa, suggesting that the enzyme is a hexamer. Six peptide sequences from protein band were obtained using ESI/MS-MS analysis. Comparison of the obtained peptide sequences with the EMBL-EBI sequence analysis toolbox and the BLASTP database showed a high degree of identity with other insect aminopeptidases.     

The effect of chronic food restriction on immunopositive ACTH cells in peripubertal female rats

In peripubertal female rats, we have previously found that 50% food restriction (FR) increases plasma IL-6, haptoglobin and both alanine transaminase (ALT) and alkaline phosphatase (AST) aminotransferases, indicating the existence of an inflammatory response. To study whether such FR influences the hypothalamic-pituitary-adrenal (HPA) axis, we examined by immunohistochemistry the morphofunctional features of pituitary adrenocorticotroppic (ACTH) cells. In FR rats the volume and volume density of ACTH cells as well as plasma ACTH levels were increased by 17.6%, 12.5% and 13.4%, respectively, in comparison with controls (p<0.05). We concluded that chronic FR is a systemic stressor in young females, capable to stimulate the HPA axis, probably as a result of IL-6 action.