ENDOCYTOSIS IN THE CROP OF THE SLUG, DEROCERAS RETICULATUM (MULLER) AND THE EFFECTS OF THE INGESTED MOLLUSCICIDES, METALDEHYDE AND METHIOCARB

Utilising the markers horseradish peroxidase (HRP) and lanthanumnitrate, uptake of endogenous material was demonstrated in thecrop of the slug, Deroceras reticulatum. Pinocytosis of HRPwas observed to occur rapidly, (within 5 min post feeding) inspecimens that had previously been starved for 48 h. Similarrates of uptake were recorded for lanthanum but this markerwas confined to a paracellular route. The effects of the molluscicidesmetaldehyde and methiocarb, following ingestion were studiedat the electron microscope level. At sub-lethal doses morphologicaldamage to the surface epithelium of the crop was attributableto both active ingredients. In addition the appearance of intracellularvacuoles within crop cells was evident from 24 h post treatmentwith methiocarb. (Received 7 February 1990; accepted 4 April 1990)     

THE EFFECTS OF STEADY AND CYCLING TEMPERATURES ON THE ACTIVITY OF THE SLUG DEROCERAS RETICULATUM

At constant temperatures, crawling activity in the slug Derocerasreticulatum has an optimum at 13°C in late winter, and 17°Cin early summer. The optimum for feeding remains at 14°C.Activity has anendogenous basis, but daytime activity increaseswith temperature and long daylengths. Cycling temperatures producemore locomotor activity and less feeding in 24 h than constanttemperatures, even when the temperature is higher at night.However, cooling stimulates and warming inhibits activity duringthe period of change and when cooling occurs at dusk, over halfthe 24 h activity occurs in the next three hours. Faster ratesof cooling produce greater responses, but can result in loweroverall activity because the slugs remain longer at low temperatures. (Received 25 May 1984;     

A COMPARISON OF THE LIFE CYCLES OF THE SLUGS DEROCERAS RETICULATUM (MULLER) AND ARION INTERMEDIUS NORMAND ON PERMANENT PASTURE

Life cycles of the slugs Deroceras reticulatum and Arion intermediuswere compared over a four-year period on permanent pasture nearOvingham, Northumberland. Both species were semelparous, theirlife cycles taking about one year. D. reticulatum, unlike A.intermedius and other species, had two overlapping generationsthat laid their eggs in late spring and autumn respectivelyand also had one instead of two immature phases in its lifecycle. The pattern and rates of growth for the immature phasesin the life cycle of A. intermedius differed markedly from thosedescribed under laboratory conditions. Growth in the infantilephase was delayed in the field by low winter temperatures whilesecond stage growth was usually delayed in late spring by dryconditions. The life cycle of A. intermedius appears to be synchronisedby seasonal changes in photoperiod, unlike that of D. reticulatum.Growth in D. reticulatum continued throughout the winter monthsexcept under exceptionally cold conditions and was not usuallydelayed by dry conditions in spring. The size of hermaphroditegland relative to body weight in D. reticulatum reached a maximumin mature-unmated slugs and then became progressively smalleras the slug approached the post-reproductive stage which wasrelatively brief. Exceptionally dry conditions in 1962 delayedthe development of the hermaphrodite gland, the maximum sizereached was significantly reduced and fewer eggs were laid. (Received 17 September 1987; accepted 2 January 1988)     

SUSCEPTIBILITY OF THE EGGS OF THE PEST SLUG DEROCERAS RETICULATUM TO CONTACT WITH METAL SALTS

Laboratory research is reported in which eggs of the pest slugDeroceras reticulatum were incubated on filter paper moistenedwith solutions of cupric sulphate, aluminium sulphate, ferricchloride and zinc sulphate at different concentrations. Afterfour or more days exposure, the median lethal doses (LD50) werebelow 10 mg metal ion/cm2 for the four metals tested. Coppershowed the highest toxicity with LD50 values below 5 mg metalion/cm2. (Received 25 May 1999; accepted 1 September 1999)     

A COMPARISON OF THE LIFE CYCLES OF DEROCERAS RETICULATUM (MULLER) AND ARION INTERMEDIUS NORMAND (PULMONATA: STYLOMMATOPHORA) AT DIFFERENT TEMPERATURES UNDER LABORATORY CONDITIONS

Growth rates and life cycles of D. reticulatum and A. intermediusare described and compared at different temperatures. D. reticulatummatures earlier in the cycle than A. intermedius and is moresensitive to changes in temperature. These differences are discussedin relation to the natural life cycles and ecology of thesespecies. (Received 9 February 1981;     

AN ELECTRON PARAMAGNETIC RESONANCE (E.P.R.) STUDY OF ENDOGENOUS TRANSITION METALS IN THE TERRESTRIAL SLUG DEROCERAS RETICULATUM

E.P.R. spectroscopy was used to detect and characterise transitionmetal ions, notably Fe and Mn, and organic free radicals withinthe tissues of the slug Deroceras reticulatum. Tissue Cu wasE.P.R. silent. The calcium complexes found within the varioussoft tissues and the shell were shown to be of the calcite configuration.It was suggested that the presence of the organic free radicalswithin the digestive gland and reproductive organ may be dueto the peroxidation of subcellular membrane lipids. (Received 15 October 1987; accepted 2 January 1988)     

黄羊消化道内不同大小食物颗粒的分布

研究了黄羊消化道内7个部位（瘤胃、网胃、瓣胃、皱胃、小肠、盲肠和直肠）食物粒径的分布规律。粒径大于0．1mm的大颗粒食物,在瘤、网胃中所占的比例较大,分别为57．8％和39．41％,在瓣胃以及瓣胃以下的消化道内容物中所占的比例急剧下降,小于10％;而粒径小于1．0mm的食物颗粒在瓣胃以及瓣胃以下的消化道中所占的比例却显著地增大,瓣胃中所占的比例为88％－95．2％。由于食物营养质量的季节性变化,黄羊消化道内食物粒径分布也呈现出明显的季节性变化。     

DIFFERENTIATION OF THE DIGESTIVE TRACT EPITHELIUM UNDER THE INFLUENCE OF THE HETEROLOGOUS MESENCHYME OF THE DIGESTIVE TRACT IN THE BIRD EMBRYOS

The endoderm of the oesophagus, proventriculus, gizzard or small intestine of the 5-day-old chick or quail embryo was cultivated in combination with homologous or heterologous mesenchyme on a WxxxOLFFyyy and HxxxAFFHNyyy medium for 7 to 21 days or on the chorio-allantoic membrane (CAM) for 8 days. With homologous mesenchyme the epithelium always differentiated homotypically. In association with heterologous mesenchyme, the differentiation of the epithelium was both homotypical and heterotypical depending on the region of the digestive tract. The oesophagus and small intestine differentiate mainly homotypically both in culture and on CAM, but the gizzard and proventriculus show heterotypic differentiation particularly on CAM. Thus, the endoderm of the digestive tract of the 5-day-old chick or quail embryo, though rather "determined", still reacts to the heterologous stimuli of the mesenchyme to some degree.     

AXOPLASMIC TRANSPORT IN THE OPTIC NERVE AND TRACT OF THE RABBIT

The axonal transport of labelled proteins was studied in the optic system of adult rabbits after an intraocular injection of [³H]Ieucine. It was demonstrated that the precursor was incorporated into protein, which was transported along the axons of the retinal ganglion cells. Intraocularly injected puromycin inhibited protein synthesis in the retina and markedly inhibited the appearance of labelled protein in the optic nerve and tract. It was further demonstrated by intracisternal injection of [³H]leucine that an intraocular injection of puromycin did not affect the local protein synthesis in the optic nerve and tract. Cell fractionation studies of the optic nerve and tract showed that the rapidly migrating component, previously described as moving at an average rate of 110-150 mm/day, was largely associated with the microsomal fraction. About 40 per cent of the total protein-bound radioactivity in this component was found in the microsomal fraction and about 15 per cent was recovered in the soluble protein fraction. Most of the labelled material moving at a rate of 1-5-2 mm/day was soluble protein. The specific radioactivity of this component was about ten times greater than that of the fast one. In the slow component about 50 per cent of the radioactivity was found in the soluble protein fraction and about 10 per cent of the radioactivity was recovered in the microsomal fraction. Radioautography demonstrated incorporated label in the neuropil structures in the lateral geniculate body as early as 4-8 hr after intraocular injection. The labelling of the neuropil increased markedly during the first week, and could be observed after 3 weeks.     

大鼠消化道内的K物质

本工作应用K物质的特异性放射免疫测定和免疫组织化学方法,研究了K物质在大鼠胃肠道内的分布、生化特点和功能。结果表明K物质样免疫活性物质广泛存在于大鼠胃肠道内,空肠含量最高,食道含量最低。K物质主要分布于胃肠道的肌间神经丛神经元内,它可促进大鼠消化道离体平滑肌收缩。外周和中枢注射K物质可抑制大鼠胃酸分泌。     

克氏原螯虾消化道内分泌细胞的鉴别与定位

目的 对克氏原螯虾（Procambarus clarkii）消化道的嗜银细胞及5种内分泌细胞进行鉴别与定位。方法应用整块组织Grimelius银染法和过氧化物酶标记的链霉亲和素（SP法）免疫组织化学技术结合生物统计学分析。结果嗜银细胞在克氏原螫虾消化道除幽门胃外的各段均有分布,位于消化道上皮细胞间及结缔组织中。五羟色胺（5-HT）细胞在除幽门胃外的消化道各段均有分布。生长抑素（SS）细胞仅在食道和后肠中有分布。胃泌素（Gas）细胞分布于除幽门胃和中肠外的消化道各段。胰高血糖素（Glu）细胞在除幽门胃外的整个消化道均有分布,在食道和贲门胃中最多。胰多肽（PP）细胞仅在肠道中有较多分布。结论克氏原螫虾消化道中存在多种内分泌细胞,它们的分布情况与其它甲壳动物存在一定的共性,然而也有其一定的特异性。     

ORIGINS AND ACTIVATION OF PROPHENOLOXIDASES IN THE DIGESTIVE TRACT OF THE CRICKET,Gryllus bimaculatus

The function of Phenoloxidases (POs) in sclerotization and defense in insects is well understood, but little is known concerning their occurrence, origins, and function in the digestive tract. In Gyrllus bimaculatus gut all of the PO activity is found in the lumen of the digestive tract, and no detectible activity is found in homogenates of the gut epithelium or secretions from incubated epithelial tissues. Prophenoloxidases (PPOs) are synthesized in the hemocytes of Bombyx mori and are transported into the cuticle. It is suggested that the PPOs in the caecal lumen of G. bimaculatus likewise are synthesized in hemocytes and are transported by unknown means into the caecal lumen, where they are activated to POs by trypsin. Peristalsis transports the POs both forward into the crop and posterior within the peritrophic membrane into the hind gut. The PPOs in the hemolymph consist of a trimer (270–280 kDa) and a tetramer (340–370 kDa). The active POs in the gut lumen consist of a monomer (85–95 kDa) in addition to an activated trimer and tetramer.     

草鱼肠道酸碱度的研究

胃肠道是一个复杂的消化系统, 每一部分都具有独特的生理特征。酸碱度(pH)是消化道重要的生理指标之一, 其对营养物质的消化、吸收和肠道微生物的生长等具有重要影响。为了研究草鱼在食物消化过程中, 肠道的酸碱度变化, 测定了草鱼肠道食物糜、肠液和黏膜的pH。结果显示, 随着食物的消化, 它们的pH都有下降的趋势。肠道食物糜pH在6.86±0.24到8.43±0.10之间, 肠液pH在7.14±0.22到8.63±0.02之间, 相同时间点相同肠段两者之间的pH差异很小, 并且在实验期间两者的pH变化趋势相同。黏膜pH在6.23±0.04到6.7±0.13之间, 为弱酸性。除了时间点12h外, 相同时间点和相同肠道部位黏膜的pH与食物糜、肠液的pH相比均有显著性差异(P<0.05)。分析发现草鱼摄食食物的pH与上述三相的pH之间均有显著性差异(P<0.05), 研究结果为草鱼消化生理及营养学研究提供了基础资料。     

扬子鳄消化道嗜银细胞的分布及形态学观察

该文用龙桂开浸银法对扬子鳄消化道嗜银细胞的分布及形态进行了观察。结果表明：嗜银细胞分布于整个消化道中,从食道到直肠。其中,十二指肠和回、直肠交接处密度很高,胃体及直肠很低。嗜银细胞形态多样。食道嗜银细胞位于上皮基部和固有膜中,呈椭圆形或不规则形。胃嗜银细胞位于胃腺部,圆形或椭圆形,有的可见明显的胞突。肠嗜银细胞位于上皮细胞之间,呈长柱形、纺锤形、长颈瓶形或锤状。多数细胞两端有较长胞突,分别与固有膜