The effect of feeding androgenic hormones on the proteolytic activity of the alimentary canal of carp Cyprinus carpio L.

The effect of feeding testosterone, 11-ketotestosterone and adrenosterone for 60 days on the proteolytic activity of the alimentary canal of carp is reported. The proteolytic activity of the gut increased in all the experimental groups compared with the controls. One month after the cessation of the drug feeding, the proteolytic activity dropped to less than the control values. A de novo synthesis of the enzymes is suspected.     

光滑足距小蠹消化道的解剖结构

采用体视显微和扫描电镜技术研究光滑足距小蠹Xylosandrus germanus(Blandford)消化道的解剖结构。结果表明,光滑足距小蠹消化道由前肠、中肠和后肠三部分组成。成虫前胃由8个骨化的前胃板组成,呈灯笼状结构。前胃板由板状部和片状部组成,板状部短而简单,片状部甚长,由斜面、咀嚼刷和关闭刚毛组成。胃盲囊着生在中肠近后端,有细管状和囊状2种,成虫分别有1对,幼虫有1对细管状和3~5对囊状。6根马氏管分成2组,1组4根,另一组2根。6根马氏管与后肠肠壁形成隐肾系统。消化道具有1对囊状和1对细管状的胃盲囊可作为光滑足距小蠹成虫的识别特征。     

鲢鳙控藻排泄物生态效应研究进展

利用鲢鳙控藻非经典生物操纵来控制蓝藻水华至今还存在分歧,主要集中在可能引起水体浮游生物个体小型化和微型藻类生物量激增等生态问题。这一现象的产生是由多种因素引起的,其中排泄物的影响不容忽视。根据国内外文献,综述了鲢鳙控藻排泄物的物质组成、未消化藻类的生长和光合活性以及消化部分在养殖水体中的迁移转化和对水体营养盐的直接贡献。由于养殖水体营养物质来源和生物转化过程的错综复杂性,往往很难用传统的方法来界定排泄物来源的氮对生态系统群落结构与功能改变的贡献及其传递过程。针对目前研究现状,建议借助叶绿素荧光成像系统和同位素示踪技术,从鱼类排泄物的角度评价鲢鳙控藻的生态后效及各自影响程度的差异,为非经典生物操纵的机理探讨和可行性分析提供参考依据。     

Left-right asymmetry in the alimentary canal of the Drosophila embryo

In many animal groups, left-right (LR) asymmetry within the body is observed. The left and right sides of the body are generally defined with reference to the anterior-posterior (AP) and dorsal-ventral (DV) axes. In this study, we investigated whether LR asymmetry is solely dependent on the AP and DV polarities in Drosophila embryos. We focused on the proventriculus, a posterior part of the foregut, and the hindgut because LR asymmetry in these body parts is highly stable in normal embryos. In embryos with a fully reversed AP polarity, LR asymmetry in both the proventriculus and the hindgut was re-oriented in relation to the reversed AP polarity. This demonstrates that inversion of AP polarity does not affect LR asymmetry of these tissues, and implies that LR asymmetry is specified in relation to the AP and DV polarities. Our findings were not consistent with the alternative hypothesis that LR asymmetry is predetermined by maternal signals that localize asymmetrically along the LR axis in the oocyte and/or early embryo.     

紫胫长夹蝗消化道的形态学观察

本文通过扫描仪对紫胫长夹蝗Choroedocus violaceipes Miller消化道内外壁进行了扫描.观察到消化道各部位的形态特征:食道直管状,由多列纵行脊组成;嗉囊由V形区、V形脊、柳叶脊、扇形脊和不规则脊组成;前胃杯形,由多列纵行脊组成;贲门是由6个凸出于肠壁的Y形结构环围而成;中肠膜质,约占消化道长度的2...     

Histochemical demonstration of carbonic anhydrase activity in the alimentary canal

Summary Carbonic anhydrase (CAH) activity was histochemically demonstrated in various parts of the alimentary canal of rat and in the stomach of man using the method of Waldeyer and Häusler (1959). The most intense histochemical reaction was observed in the parietal cells of the rat stomach, and reactions of decreasing intensity in the epithelial cells of the colon, appendix, jejunoileum, duodenum and oesophagus in the order mentioned. An intense reaction was also observed in the parietal cells of the stomach of man and a weak activity in the pyloric glands. After electrophoresis on cellulose acetate film the CAH activity in human and rat stomach mucosa showed one band with the same migration rate as the fastest moving band of the erythrocyte CAH.     

An in situ estimate of daily food consumption and alimentary canal evacuation rates of common carp, Cyprinus carpio L.

Daily food consumption and alimentary canal evacuation rates for common carp, Cyprinus carpio L., were estimated at 4-week intervals from April to October 1979. Both the rate of food evacuation and its relationship to temperature were described by an exponential function. Gut evacuation rates ranged from 6.0% of gut contents per hour at 9°C to 32.7% h⁻¹ at 26.5°C. Temperature accounted for 72–91% of the variation in gut evacuation rate among months. Daily food consumption varied from a low of 3.87 mg g⁻¹ of fish wet wt per day in April at 14°C (0.39% of wet body wt) to a high of 40.75 mg g⁻¹ (4.08%) in August at 26.5°C. Although a greater quantity of food appeared to be consumed during the morning in spring and early summer and a greater amount in the evening after July, there was not a statistically significant time of day for peak feeding activity. The field method described here seemed to provide reasonable estimates of food consumption compared with other field and laboratory studies.     

Microspines in the alimentary canal of arthropoda,onychophora, annelida

The presence and variation of microspines within the foregut and hindgut of the taxa Arthropoda, Onycophora, and Annelida were presented. Microspines appear to be sympleisiomorphic to the Arthropoda sensu stricto. Unispinose microspines constitute the original ancestral condition, and these have been retained and variously modified within the classes to aid in filtering ingested food, food movement through the gut and retain symbionts, and possibly protect the cellular linings of the gut in particulate food eaters.     

Slc4-like anion transporters of the larval mosquito alimentary canal

Mosquito larvae exhibit luminal pH extremes along the axial length of their alimentary canal that range from very alkaline (pH>10) in the anterior midgut to slightly acid in the hindgut. The principal buffer in the system is thought to be bicarbonate and/or carbonate, because the lumen is known to contain high levels of bicarbonate/carbonate and is surrounded by various epithelial cell types which express a variety of carbonic anhydrases. However, the precise mechanisms responsible for the transport of bicarbonate/carbonate into and out of the lumen are unclear. In the present study, we test the hypothesis that SLC4-like anion transporters play a role in bicarbonate/carbonate accumulation in the larval mosquito alimentary canal. Molecular, physiological and immnuohistochemical characterizations of Slc4-like transporters in the gut of larval mosquitoes (Aedes aegypti and Anopheles gambiae) demonstrate the presence of both a Na(+)-independent chloride/bicarbonate anion exchanger (AE) as well as a Na(+)-dependent anion exchanger (NDAE). Notably, immunolocalization experiments in Malpighian tubules show that the two proteins can be located in the same tissue, but to different cell types. Immunolabeling experiments in the gastric caecae show that the two proteins can be found in the same cells, but on opposite sides (basal vs. apical). In summary, our results indicate that the alimentary canal of larval mosquitoes exhibits robust expression of two SLC4-like transporters in locations that are consistent with a role in the regulation of luminal pH. The precise physiological contributions of each transporter remain to be determined.     

The contribution of silver carp (Hypophthalmichthys molitrix) to the biological control of Netofa reservoirs

When silver carp were introduced into the Netofa reservoirs at an initial density of 300–4500 fish per hectare in order to control phytoplankton and zooplankton, there was a significant reduction of algae, zooplankton, and suspended organic matter; the silver carp prevents the growth of blue-green algae.Annual yield ranged from 600 to 1500 kg per hectare. The growth of individual fish after 6 to 8 years was 6 to 15 kg per fish.Introducing silver carp to reservoirs as a means of biological control creates a balanced ecological system in which the interspecific competition is minimal and the environmental improvements are considerable.Silver carp and bottom-feeding fish create a positive synergism in the water-body by filtering phytoplankton and zooplankton from the water, excreting a major part of it to the bottom and enriching it with organic matter suitable for zoobenthos.     

A demonstration of bacterial conjugation within the alimentary canal of Rhabditis nematodes

Abstract: Rhabditis nematodes fed a diet of Escherichia coli defecate viable undigested bacteria. These bacteria retain phenotypic characteristics, including those encoded on plasmids. Nematodes can survive a 2-min surface sterilization with 2% chlorine bleach; internalized bacteria also survive this treatment and are released in the nematode wastes. Bacteria alone or on the surface of dead nematodes are unable to survive incubation with this solution. There were 3.2 × 10⁵ viable bacteria per nematode, indicating that sufficient bacteria were present for gene transfer. Transconjugants ( lac ⁻ nal ^R str ^R cm ^R) were recovered in the nematode fecal material following a protocol where nematodes were initially fed a plasmidless lac ⁻ nal ^R str ^S cm ^S E. coli and then, after surface sterilization, a lac ⁺ nal ^S E. coli plasmid donor containing the conjugative R100JA ( str ^R cm ^R) plasmid. The presence of plasmids in the transconjugants was confirmed by gel electrophoresis. The occurrence of conjugation in the gut was confirmed by dissection of individual surface-sterilized nematodes and isolation of transconjugants.     

Molecular characterization of glutathione peroxidase gene from the liver of silver carp, bighead carp and grass carp

The cDNAs encoding glutathione peroxidase (GPx) were cloned and sequenced from the liver of three Chinese carps with different tolerance to hepatotoxic microcystins, phytoplanktivorous silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis), and herbivorous grass carp (Ctenopharyngodon idellus). Using genome walker method, a 750 bp 5'-flanking region of the silver carp GPx gene was obtained, and several potential regulatory elements were identified in the promoter region of the GPx gene. The silver carp GPx gene was widely expressed in all tissues examined. Despite phylogenetic analysis, assigning this newly described carp GPx to the group of mammalian GPx2, the carp GPx seems more similar to GPx1 from a physiological point of view. The constitutive expression pattern of the three carp liver GPx gene, shows a positive relationship with their tolerance to microcystins.     

Potential biological control of Erwinia tracheiphila by internal alimentary canal interactions in Acalymma vittatum with Pseudomonas fluorescens

Aims

We aim to determine if Pseudomonas fluorescens is a viable biological control for Erwinia tracheiphila within the insect vector, Acalymma vittatum.

Methods and Results

Pseudomonas fluorescens secreted fluorescein and inhibited growth of E. tracheiphila in disc diffusion assays. To determine if this antagonism was conserved within the insect vector, we performed in vivo assays by orally injecting beetles with bacterial treatments and fluorescent in situ hybridization to determine bacterial presence within the alimentary canal.

Conclusions

Pseudomonas fluorescens inhibited the growth of E. tracheiphila on a nutrient‐limiting medium. In situ experiments demonstrated that P. fluorescens is maintained within the alimentary canal of the beetle for at least 4 days, and co‐occurred with E. tracheiphila. When beetles were first presented with Pseudomonas and then challenged with E. tracheiphila, E. tracheiphila was not recovered via FISH after 4 days. These data suggest that P. fluorescens has potential as a biological control agent to limit E. tracheiphila within the insect vector.

Significance and Impact of the Study

This is a novel approach for controlling E. tracheiphila that has the potential to decrease reliance on insecticides, providing a safer environment for pollinators and growers.     

Distribution of bombesin-like peptides in the alimentary canal of several vertebrate species

The objective of this study was to quantitate and characterize the variants of bombesin-like immunoreactivity in the alimentary canal of the rat, rabbit, hawk, owl, dog, monkey and human. Bombesin-like immunoreactivity was found throughout the entire gastrointestinal tract of all species studied. In the rat, the highest concentration of bombesin-like immunoreactivity was found in the colon. Gel chromatography showed that bombesin-like immunoreactivity corresponded to gastrin-releasing peptide (GRP-27) and GRP-10. In the dog, the greatest concentration of bombesin-like immunoreactivity was observed in the mucosal layer of the fundus, whereas the concentration of bombesin-like immunoreactivity in the muscle layer of the dog did not vary significantly from region to region. Gel chromatography showed that bombesin-like immunoreactivity in the dog corresponded to GRP-27, bombesin, GRP-10, and a smaller fragment. In the human, the concentration of bombesin-like immunoreactivity did not vary significantly from region to region in the mucosal and muscular layers. Gel chromatography of human fundal mucosa showed that bombesin-like immunoreactivity peaks occur in the regions of GRP-27, bombesin and GRP-10. These findings substantiate the observation that bombesin-like peptides play a variety of roles in the regulation of gut function.     

Digestion of plant monogalactosyldiacylglycerol and digalactosyldiacylglycerol in rat alimentary canal

We investigated digestion of orally fed galactoglycerolipids such as monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) from wheat flour in the rat alimentary canal, especially focusing on the digestive fates of deacylated galactosylglycerol structures. After a single oral administration of MGDG (20 mg/rat), monogalactosylmonoacylglycerol and monogalactosylglycerol (MGG) were found to be major digestion products in the intestinal tract. Similarly, digalactosylmonoacylglycerol and digalactosylglycerol (DGG) were confirmed to be present in the intestinal tract after DGDG ingestion (20 mg/rat). In rats fed wheat flour glycolipids (42 mg MGDG and 81 mg DGDG per rat), completely deacylated galactosylglycerols (MGG and DGG) were not detected in portal plasma. Although the deacylated galactosylglycerols were not significantly decomposed by intestinal mucosa in vitro, they were hydrolyzed by cecal contents. The results demonstrated that orally ingested plant galactoglycerolipids in the rat alimentary canal are rapidly hydrolyzed into constituent fatty acids and that hydrophilic galactosylglycerols and the hydrophilic backbone galactosylglycerols are not absorbed from intestine or degraded into galactose and glycerol in the intestinal tract. Therefore, the presence of deacylated galactosylglycerols may affect the fermentative activity of enterobacteria in the cecum and colon.