Digestive α-amylase activity in Aelia acuminata L. (Hemiptera: Pentatomidae)

Activity of α-amylase was revealed in the midgut and salivary glands of the wheat and barley pentatomid pest, A. acuminata. The activity was determined in salivary gland more than those in midgut. Optimal activity of the enzyme occurred at 40°C. Optimal pH activity in salivary gland (pH = 6) was more than those in the midgut (pH = 4.5). pH stability analysis of the enzyme showed that the enzyme is more stable at slightly acidic pHs than those at acidic and alkaline pHs. However, α-amylase is more stable at acidic pH in long period of time. Temperature stability analysis determined the enzyme was remarkably active over a broad range of temperature (5–40°C). α-Amylase activity was decreased after addition of MgCl₂, Tris, Triton X-100, CuSO₄, SDS, urea and CaCl₂. The salts NaCl and KCl increased the enzyme activity from midgut and salivary glands. Zymogram analysis of midgut and salivary gland extract showed at least two bands of amylase activity in the midgut and salivary glands.     

A review on digestive TAG-lipases of insects

Digestion in insects is a multi-step process to afford nutritional requirements of biological activities. The process starts with nervous stimuli and continues with biochemical activities of digestive enzymes as well as several pumps to digest and absorb the obtained molecules. Carbohydrases, lipases and proteases are the three main digestive enzymes involved in digestion process. Lipases seem to be very important not only for digestive role but also for esteratic activity so that some experts consider lipases as the Class 3 of general esterases. Digestive lipases divided into different groups based on their biological roles namely triacylglycerol lipases, phospholipases and two types of phosphatases. Briefly, triacylglycerol lipases (TAG-lipases) are the hydrolysing enzymes that affect the outer esteric links of triacylglycerols in ingested food. Phospholipases including PLA2 and PLA1 remove phosphatide fatty acids attached to the Position 2 and Position 1. Finally, Alkaline and acid phosphatases are the enzymes that hydrolyse phosphomonoesters under alkaline or acid conditions, respectively. In this review, presence and physiological role of digestive TAG-lipases are explained and their possible importance will be discussed in insect.     

A synonymous mutation in NOD2 gene was significantly associated with non-specific digestive disorder in rabbit

Nucleotide-binding oligomerization domain containing 2 (NOD2) plays a pivotal role in the host innate and adaptive immunity by recognizing the pathogenic agents. Therefore, its genetic polymorphisms and association with susceptibility to infectious diseases have been widely reported in human and farm animals. In the present study, we investigated the genetic polymorphisms in 3171 bp coding region of NOD2 gene and association with non-specific digestive disorder (NSDD) in rabbit. A total of four coding single-nucleotide polymorphisms (cSNPs) were detected. Among them, c.2961C>T was further genotyped for case (n = 176) and control (n = 130) based on association analysis, which revealed that C allele carried the potential protective role for susceptibility to NSDD with the odds ratio (OR) values of 0.52 (95% confidence interval (CI) 0.37–0.73, P < 0.01). Under the dominant inheritance model, CC genotype was associated with decreased susceptibility to NSDD (OR = 0.38, 95% CI 0.24–0.60, P < 0.01). Along with the aggravation of NSDD, we observed higher mRNA expression of NOD2 gene (P < 0.05). However, the mRNA expression pattern of CC genotype would be interacted by the different status of NSDD, which only showed the significantly increased level in severe NSDD group (P < 0.05). These results revealed by genetic association and gene expression analysis suggested that the NOD2 gene was associated with the susceptibility to NSDD in rabbit. However, the causative mutations linked to c.2961C>T and corresponding functional depiction should be further explored by performing exhaustive genetic studies.     

REGULATION OF AMYLASE,CELLULASE AND CHITINASE SECRETION IN THE DIGESTIVE TRACT OF THE TWO‐SPOTTED FIELD CRICKET,Gryllus bimaculatus

The secretion of amylase and cellulase in Gryllus bimaculatus is determined by increased food intake, whereby shortly after molting food consumption increases. About half of the standing amylase concentration (activity) in the endothelial cells can be secreted within 30 min. The peak of amylase and cellulase secretion that occurs in the photophase is related to the feeding peak in the previous scotophase. The secretion of chitinase on the other hand is primarily controlled by the molting cycle. Only amylase secretion was affected by calcium in the incubation medium, suggesting an apocrine release mechanism. Refeeding experiments (after 5 days without food) suggest that the release of amylase in response to a nutrient in the lumen (glucose) is not due to simple stimulation of exocytosis, but rather a stimulation of synthesis.     

Characterization and Structure Analysis of a Novel Bacteriocin,Lacticin Z,Produced by Lactococcus lactis QU 14

A novel bacteriocin, lacticin Z, produced by Lactococcus lactis QU 14 isolated from a horse’s intestinal tract was identified. Lacticin Z was purified through a three step procedure comprised of hydrophobic-interaction, cation-exchange chromatography, and reverse-phase HPLC. ESI-TOF MS determined the molecular mass of lacticin Z to be 5,968.9 Da. The primary structure of lacticin Z was found to consist of 53 amino acid residues without any leader sequence or signal peptide. Lacticin Z showed homology to lacticin Q from L. lactis QU 5, aureocin A53 from Staphylococcus aureus A53, and mutacin BHT-B from Streptococcus rattus strain BHT. It exhibited a nanomolar range of MICs against various Gram-positive bacteria, and the activity was completely stable up to 100 °C. Unlike many of other LAB bacteriocins, the stability of lacticin Z was emphasized under alkaline conditions rather than acidic conditions. All the results indicated that lacticin Z belongs to a novel type of bacteriocin.     

扬子鳄消化道Ghrelin免疫活性细胞的分布及其在冬眠期的密度变化

目的 研究扬子鳄（Alligator sinensis）消化道中生长素释放肽ghrelin免疫活性（IR）细胞的分布、组织定位及其在冬眠期的变化.方法 应用链霉亲和素-生物素-过氧化物酶复合物（SABC）免疫组织化学方法结合生物统计学分析.结果 Ghrelin-IR细胞在扬子鳄的小胃密度最高,在胃贲门部、胃体和胃幽门部有少量分布,主要位于胃腺上皮细胞之间.在食管、十二指肠、空肠、回肠和直肠中均未检测出ghrelin-IR细胞.冬眠期小胃ghrelin-IR细胞显著性减少（P〈0.01）,其它部位无显著性变化（P〉0.05）.结论扬子鳄消化道ghrelin-IR细胞的分布同其它动物有相似之处,也有其一定的特异性.Ghrelin在扬子鳄冬眠期的代谢变化和能量稳态的调节中起重要作用.     

A change in the pattern in circadian running‐wheel activity after lesions of the intergeniculate leaflet and ventral lateral geniculate nucleus in the Syrian hamster

Abstract

The suprachiasmatic nuclei (SCN) contain the endogenous mammalian circadian pacemaker, which generates the circadian rhythm in locomotor activity. In Syrian hamsters with free‐running rhythms, the onset of running‐wheel activity is very precise and predictable while the end (offset) is more variable. From the thalamic intergeniculate leaflet (IGL) and the ventral lateral geniculate nucleus (vLGN) a projection to the SCN originates. Animals with a lesion aimed at the IGL/vLGN and sham‐and unoperated controls were kept in continuous darkness. With linear regression, lines were fitted through 10 successive onsets and offsets of activity and the mean deviation of the onsets and offsets from the fitted lines was determined. Animals with a complete or partial lesion of the IGL/vLGN had a smaller mean deviation of the circadian activity offset from the fitted regression line (0.313 h) compared with the grouped control animals (0.678 h). To test the difference statistically, we compared the sum of the square residuals of the circadian offsets between the groups. This difference was highly significant (F(69,64)=4.16, p<0.0001), which indicates that animals with a lesion of the IGL/ vLGN have a less variable circadian offset of running‐wheel activity. No differences were observed in the variability in the circadian onset of locomotor activity between experimental and control animals. It is concluded that the IGL/vLGN influence the variability of the offset of the circadian running‐wheel activity.