Some peptide-like colocalizations in endocrine cells of the pyloric caeca and the intestine of Oncorhynchus mykiss (Teleostei)

Summary The coexistence of immunoreactivities to cholecystokinin, glucagon, glucagon-like peptide 1, salmon pancreatic polypeptide, neuropeptide tyrosine, and peptide tyrosine tyrosine was studied immunocytochemicaly, revealing for the first time in fish intestine the existence in the same cell of immunoreactivities to cholecystokinin-glucagon/glucagon-like peptide 1, cholecystokinin-salmon pancreatic polypeptide, glucagon/glucagon-like peptide 1-salmon pancreatic polypeptide, glucagon/glucagon-like peptide 1-neuropeptide tyrosine, salmon pancreatic polypeptide tyrosine tyrosine, and glucagon/glucagon-like peptide 1-peptide tyrosine tyrosine. Colocalization of cholecystokinin-salmon pancreatic polypeptide was observed only in the pyloric caeca of the rainbow trout Oncorhynchus mykiss, while the other colocalizations also occurred in proximal and middle intestinal segments. In all cases, endocrine cells immunoreactive to only one of the paired antisera were detected except for anti-glucagon and anti-glucagon-like peptide 1, which always immunostained the same cells.     

Microprobe analysis of Na,K, Cl,P, S,Ca, Mg and H2O in frozen-hydrated sections of anterior caeca of the locust, Schistocerca gregaria

Electron probe X-ray microanalysis of frozen-hydrated sections was carried out for sodium, potassium, chlorine, calcium, magnesium, sulphur, phosphorus and water concentrations in the lumen and epithelial cells of freshly-fed adult female desert locusts, and in blood of fed and starved locusts.Sodium and chloride were found to be at a much lower level in the lumen and cells than potassium, and at a much higher level in the blood. The luminal folds were plugged with a dense organic matrix, presumed to be polyanionic glycosaminoglycans, which appeared to restrict access of charged moieties of the absorptive sites. The data were consistent with a model of caecal fluid absorption in which a passive flux of potassium from lumen to blood, possibly assisted by an active absorption of chloride, drives fluid into the blood. Unlike the case of the vertebrate intestine, active absorption of sodium from the lumen would not contribute significantly to the fluid transport in vivo.     

The occurrence of bacteria and mycoplasma like organisms in a monogenean parasite Diclidophora merlangi.

Bacteria are not normal residents of the gut caeca of Diclidophora merlangi and are found in the gut lumen only as a result of contamination of the culture medium. Mycoplasma-like organisms have been found in the cytoplasm of gland cells associated with the anterior alimentary tract of the worm. Their occurrence is infrequent and does not involve cytoplasmic damage in the gland cell. Unlike the gut luminal bacteria, the mycoplasmas can be found in fresh worms and in worms kept in culture media containing antibiotics.     

Ontogeny of lipase expression in winter flounder

The partial sequencing of two lipases from winter flounder Pseudopleuronectes americanus , one most closely related to gastric, lingual and lysosomal acid lipase from other vertebrates and one most closely related to bile salt-activated lipase, is reported. Biochemical analyses of enzymatic activity demonstrated the greater contribution made by bile salt-activated lipase relative to neutral bile salt-independent lipase. Using molecular techniques, the tissue-specific expression of bile salt-activated lipase in pancreatic tissue and acid triacylglycerol lipase in a wide variety of organs was demonstrated. Furthermore, the developmental expression of these types of lipase in larval fish was established.     

Assessment of structural and functional similarities and differences between caeca of the bluegill

Bluegill Lepomis macrochirus possess six to eight gastrointestinal caeca, >70% having seven. The terminal caeca toward abdominal edge (C6, C7) were always larger than the terminal caeca toward the vertebral column (C1, C2) and middle caeca (C3, C4, C5). The caeca varied in relative thickness of the histological layers and lumen space. The terminal caeca (C1, C2, C6, C7) have anatomical positional advantage over, and possess more contents, than the middle ones (C3, C4, C5) in both field and laboratory conditions. Hence, all caeca in bluegill may have the same function but their functional potentials are not the same. Two factors, size of caeca and anatomical position of caeca, apparently work synergistically to cause variation in their functional efficiency.     

Calcium reabsorption in the posterior caeca of the midgut in a terrestrial crustacean,Orchestia cavimana

Summary During molting, the epithelium of the posterior caeca (PC) of the midgut in the terrestrial crustacean, Orchestia cavimana, is active in calcium turnover. In the preexuvial period, epithelial cells that progressively differentiate into cell-type III secrete ionic calcium (originating from the old cuticle) from the base to the apex of the cell within a typical extracellular network of channels; the calcium is then stored in the PC lumen as calcareous concretions. Immediately after exuviation, the epithelial cells rapidly differentiate into cell-type IV, reabsorbing calcium from the concretions through successive generations of spherites which quickly appear, grow, and then disappear from the apex to the base of the same extracellular network. The PC epithelium is thus alternatively calcium-loaded and unloaded. When the calcium-reabsorbing process is complete (average 48 h after exuviation), the epithelial cells again differentiate into two different regional cellular types (cell-type I in the distal segment and cell-type II in the proximal segment) characteristic of the intermolt period.The dynamic changes in the PC epithelium during the postexuvial period are discussed, including the characteristic features of cell-type IV and of the reabsorption spherites.     

臭腹腺蝗（直翅目：锥头蝗科）胃盲囊的异速生长和功能特性

通过对臭腹腺蝗Zonocerus variegatus（直翅目：锥头蝗科）6个若虫期及成虫期主消化道和胃盲囊分段进行解剖和测量,对其胃盲囊的异速生长和功能特性进行了研究。结果表明,胃盲囊和主消化道的生长是不同速的。胃盲囊前段较后段生长速率更高,但两者生长速率显著相关。消化道和胃盲囊的平均长度亦显著相关。随年龄增长,消化道的生长速率降低,而胃盲囊的生长速率上升。与胃盲囊前段功能相同,胃盲囊后段亦具有消化和吸收功能,被认为能在营养缺乏的旱季起到增加肠胃吸收面的功能。     

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。     

南极鱼两种寄生海蛭的研究

从南极海纽喀姆湾(南纬66°17′,东经110°32′)的南极鱼属Notothenia鱼体上得到两个海蛭标本。经鉴定为多皱海蛭Pontobdella rugosa Moore,1938和椎蛭属Notobdella的一新种。前者的环带后区环的分割明显并因许多大、小结节变得崎岖不平。在一完全体节(ⅫⅠ-ⅩⅫⅠ)里环的通常大小关系是8_2(?)a_1>b_5=b_(60)扭椎蛭新种Notobdella streptocheles sp.nov.呈S形弯曲井从稍膨大的中部向两端渐渐变细。在前吸盘上没有眼。尾吸盘与躯干部的最大体宽相等。在—完全体节(Ⅹ-ⅩⅩⅣ)里环的通常大小关系是a_1=a_2>b_3=b_(60)嗉囊有6对盲囊和一个后嗉囊盲囊。