Localization and fate of aluminium in the digestive gland of the freshwater snail Lymnaea stagnalis

The digestive gland of the freshwater snail Lymnaea stagnalis, exposed to water containing an elevated concentration of aluminium at neutral pH for up to 30 days, followed by a 20 day recovery period, was examined by light and electron microscopy and X-ray microanalysis. Aluminium was localized in the yellow granules present in the digestive and excretory cells and in the green and small granules present in the digestive cells. More aluminium, silicon, phosphorus and sulphur were present in all three granule types from aluminium exposed snails. The number of yellow and green granules from the digestive gland of aluminium exposed snails showed a progressive increase over the experimental period compared to controls. The number and aluminium content of the granules is likely to reflect the role of the digestive gland as a 'sink' for accumulated aluminium. We propose that intracellular monomeric silica is involved in the detoxification of aqueous aluminium which at neutral pH is largely in the form of an insoluble polyhydroxide. The increased amounts of sulphur and phosphorus in the granules are likely to be part of a broad response to metal loading but probably do not play a significant role in the storage and detoxification of aluminium.     

Nucleotidase activities in membrane preparations of nervous ganglia and digestive gland of the snail Helix aspersa

Nucleotide-metabolizing enzymes play an important role in the regulation of nucleotide levels. In the present report, we demonstrated an enzyme activity with different kinetic properties in membrane preparations of the nervous ganglia and digestive gland from Helix aspersa. ATPase and ADPase activities were dependent on Ca2+ and Mg2+ with pH optima approximately 7.2 and between 6.0 and 8.0 in digestive gland and nervous ganglia, respectively. The enzyme activities present in membrane preparations of these tissues preferentially hydrolyzed triphosphate nucleotides. In nervous ganglia, the enzyme was insensitive to the classical ATPases inhibitors. In contrast, in digestive gland, N-ethylmaleimide (NEM) produced 45% inhibition of Ca(2+)-ATP hydrolysis. Sodium azide, at 100 microM and 20 mM, inhibited Mg(2+)-ATP hydrolysis by 36% and 55% in digestive gland, respectively. The presence of nucleotide-metabolizing enzymes in these tissues may be important for the modulation of nucleotide and nucleoside levels, controlling their actions on specific purinoceptors in these species.     

Renal sorbitol accumulation and associated enzyme activities in diabetes

Streptozotocin-induced diabetes increased sorbitol levels in the rat renal medulla. The activities of renal medullary aldose reductase and sorbitol dehydrogenase, responsible for the formation and metabolism of sorbitol, favor sorbitol formation and did not change in diabetes. The elevated sorbitol concentration appears to be due to an increase in medullary glucose concentration.     

Developmental changes in the activities of prostaglandin synthesizing enzymes in the digestive and immune systems of rat

The developmental changes of prostaglandin (PG) synthesizing enzymes in the digestive system (stomach and small intestine) and the immune system (spleen and thymus) of rats were investigated. In all the digestive organs, the predominant PG produced from PGH2 changed at around 2 weeks after birth to another PG. Further, the predominant activities of PG synthesizing enzymes were different organ by organ in the digestive system. In the case of the immune system, only the activity of PGD2 synthesizing enzyme displayed a significant increase during development and the activities of other PG synthesizing enzymes remained insignificant throughout the development. These results suggest that PGs may play important roles during the development of each organ.     

Histochemical changes of carbohydrate and protein contents in the digestive gland cells of the land snail Monacha cartusiana following starvation

The present study was designed to investigate histochemically the detection of carbohydrate and protein in the normally feeding snails and after 15 and 30 days of starvation. Generally, abundant carbohydrate and protein materials were detected in the component cells of the digestive gland of normally feeding snails. The results of this investigation revealed a pronounced decline of carbohydrates in the digestive gland cells of Monacha cartusiana snails after starvation. Severe decline in carbohydrate content was observed especially after 30 days of starvation. Moreover, protein inclusions have exhibited a week stainability in the digestive gland cells of these snails as a consequence of starvation.     

Metal accumulation and enzyme activities in gills and digestive gland of pearl oyster (Pinctada fucata) exposed to copper

The effects of exposure to copper under laboratory-controlled conditions were investigated in the pearl oyster, Pinctada fucata. Metal accumulation and the activity of five enzymes were measured: two immune defense involved enzymes [acid phosphatase (AcPase) and phenoloxidase (PO)], two antioxidant enzymes [superoxide dismutase (SOD) and Se-dependent glutathione peroxidase (Se-GPx)] and one metal-sensitive enzyme [alkaline phosphatase (ALP)]. Analyses were carried out in gills and digestive gland of oysters exposed to 0.05 microM and 0.5 microM copper, respectively, at 12, 24, 48 and 72 h of exposure. The digestive gland of P. fucata was the main copper accumulation organ when oysters were exposed to low concentrations, whereas gills became the target organ in oysters exposed to high concentrations. The adaptation and recovery of the oysters were observed in our study. Levels of the copper accumulation and the sensitivity to copper were the main, if not, part of the reasons for the various responses of the selected enzymes. Se-GPx may potentially be used as biomarkers in biotesting of marine heavy metal pollutions. The enzymatic responses were compared with those of other studies and the possible reasons were discussed.     

The neuropeptide FMRFamide can protect cells against apoptosis in the snail digestive gland

FMRFamide-related peptides are widespread neurotransmitters or neurohormones regulating somatic or visceral motor activity. Some recent data indicate that these neuropeptides may be involved in the control of cell proliferation and apoptosis. In this work we investigated the possible effect of FMRFamide on cell viability in an invertebrate-type proliferating tissue. As a model, we used the midintestinal gland of the snail, Helix lucorum Linnaeus. Immunohistochemistry demonstrated the direct innervation of the gland cells by FMRFamide-containing nerve fibers. Midintestinal glands of snails were injected with 50 μM FMRFamide and the control with sterile deionised water or bovine serum albumin (BSA). Injections were administrated 4 times. Transmission electron microscopy, annexin V-labeling, thiazolyl blue (MTT) viability tests and ploidy analyses were carried out to define the viable/dead cell ratio in the tissue samples. FMRFamide increased the MTT-reduction of tissues, reduced the amount of apoptotic nuclei and annexin V-labeled cells. Deionised water or BSA injection induced cell death. Cell cyle analysis revealed that FMRFamide significantly elevated the amount of cells in G₀/G₁ phase, but did not induce mitosis. We conclude, that the FMRFamide can be a life-signal for cells, protect them from apoptosis without altering mitosis. The project was supported by OTKA grant No. T 042762.     

The localization of aluminium in the digestive gland of the terrestrial snail Helix aspersa

The terrestrial snail Helix aspersa was exposed to food containing elevated levels of aluminium for up to 33 days and the digestive gland examined by light and electron microscopy and X-ray microanalysis. Four types of cell are found in the digestive gland, (digestive, excretory, calcium and thin) although aluminium was only found in the excretory cells. The aluminium was localised in the 'yellow' or excretory granules that are a characteristic feature of the excretory cells. Aluminium was only found in the granules of snails fed aluminium but there was no difference in the appearance of granules from control or aluminium-fed snails. The granules were large (up to 20 mum in diameter), irregularly shaped and electron-dense. Sulphur, phosphorus and calcium were detected in granules from all snails. The presence of sulphur may indicate protein residues. The amount of aluminium and phosphorus in the granules increased over the experimental period but the number of granules did not change. Levels of aluminium in the granules decreased when the snails were given control food. The role of the excretory granules in the localisation, detoxification and excretion of aluminium is discussed.     

枣花病对意大利蜜蜂消化酶和解毒酶系活性的影响

[目的]枣花期蜜蜂易发生枣花中毒(又称枣花病),致使大量采集蜂死亡.本研究初步探讨了枣花病对蜜蜂的毒性作用机理.[方法]以正常的意大利蜜蜂Apis mellifera ligustica工蜂为对照,采用分光光度法测定山西临猗、太谷和临县患枣花病的意大利蜜蜂工蜂体内淀粉酶、蛋白酶、蔗糖酶、果胶酶、海藻糖酶、酯酶(este...     

北草蜥几种消化酶活力比较

应用酶学分析法测定了越冬后北草蜥胃、肠组织中蛋白酶、淀粉酶、纤维素酶的活力。结果表明 ,不同年龄、性别的北草蜥同一组织中消化酶活力有显著差异 ;不同地理种群的北草蜥同一组织中消化酶活力有显著差异 ;不同消化酶在北草蜥同一组织中的活力有显著差异 ;在北草蜥不同的组织中同一消化酶的活力有显著差异。说明北草蜥消化酶的活力与年龄、性别、部位和地理环境等因素有关 ,受食物组成、能量需求和遗传等因素的影响 ,产生了不同的酶活力和分布。这也说明生物长期适应环境 ,形成了不同的代谢水平     

Heat waves trigger swift changes in the diet and life-history of a freshwater snail

Hydrobiologia - Extreme climatic events, such as heat waves, may induce changes in nutrient acquisition by omnivorous ectotherms. Likely modulated by the intensity, frequency and duration of these...     

Feeding habits and ontogenic changes in digestive enzyme patterns in five freshwater teleosts

Feeding habits and the activity of digestive enzymes (total alkaline proteases, α‐amylase and lipase) from dace Leuciscus leuciscus, roach Rutilus rutilus, Prussian carp Carassius auratus gibelio, perch Perca fluviatilis and pikeperch Sander lucioperca fry were studied in the Malye Chany Lake–Kargat Estuary (western Siberia, Russia). The diet of fry from all studied species was mainly composed of chironomid larvae and zooplanktonic organisms (i.e. cladocera and copepoda), whereas carnivorous species such as P. fluviatilis and S. lucioperca also preyed on fry from other fishes while detritus and microalgae were also important in the diet of ommivorous species. When comparing diet similarity (Sørensen–Dice index, Q_S) among fry at different stages of development, both omnivorous and carnivorous species showed a high level of similarity (0·67 < Q_S < 0·89 and 0·73 < Q_S < 0·89, respectively). Diet similarity values were in agreement with the overall digestive activity profile analysed by cluster analysis. Diet similarity suggested potential trophic competition when zooplanktonic and benthic prey began to decline towards autumn. The analysis of pancreatic digestive enzymes revealed a correlation among their activities and fry feeding habits with α‐amylase:total proteases (A:P) values higher than 1 in omnivorous species and lower (A:P ≤ 1) in carnivorous species.     

pH值对中国龙虾消化酶活力的影响

采用酶学分析方法研究了pH对中国龙虾胃蛋白酶、类胰蛋白酶、淀粉酶、纤维素酶和脂肪酶活力的影响。结果表明,在设定的pH范围内,中国龙虾各消化酶的活力均随着pH的升高呈现先升后降的变化趋势。其中,胃、肠、肝胰腺内胃蛋白酶最适pH均为2.2,类胰蛋白酶最适pH分别为8.8-9.2、8.4、8.8,淀粉酶最适pH分别为7.0、7.0、7.4,纤维素酶最适pH分别为4.2、4.2-4.6、5.4,脂肪酶最适pH分别为7.2-7.6、7.2、6.8-7.2。同时测得中国龙虾胃、肠、肝胰腺内的生理pH分别为5.33、6.93、6.60。中国龙虾的消化酶活力存在器官特异性。在最适pH下,胃蛋白酶活力顺序为胃>肠>肝胰腺,类胰蛋白酶、纤维素酶、脂肪酶的活力顺序均为肝胰腺>肠>胃,淀粉酶的活力顺序为肠>肝胰腺>胃。     

中华真地鳖中肠主要消化酶的活性研究

以中华真地鳖EupolyphagasinensisWalker为研究材料,测定人工饲养和野生地鳖虫在不同生长阶段消化酶的活性以及温度及pH对人工饲养地鳖虫中肠消化酶活性的影响。结果表明,在地鳖虫生长发育过程中,蛋白酶和脂肪酶活性随发育而逐渐增强,淀粉酶活性却随发育而逐渐减弱。在低龄若虫、高龄若虫和成虫阶段,人工饲养地鳖虫蛋白酶活力比野生地鳖虫低,人工饲养地鳖虫淀粉酶和脂肪酶活力比野生地鳖虫高;在30～60℃的范围内,人工饲养地鳖虫蛋白酶、淀粉酶的适宜温度范围为40～50℃,脂肪酶的适宜温度范围为35～45℃;蛋白酶、淀粉酶和脂肪酶的适宜pH范围分别为6.5～7.5,5.6～6.4和7.5～8.5。     

Antioxidative enzymes activities and accumulation of steroids in hairy roots of Trigonella

Steroidal sapogenins and phytosterols are a group of secondary metabolites which are very considerable in the pharmaceutical industry. Fenugreek (Trigonella foenum-graecum L.) is the good source of these compounds. In recent decades, there is a great interest to production of these compounds by cultivation of transformed roots. In present study, hairy roots induction in two Trigonella species (T. foenum-graeceum, T. monantha) with three strains of Agrobacterium rhizogenes (15,834, A4 and wt) was investigated. Transgenic status of roots was confirmed by PCR using rolB specific primers. Virulence of these strains was examined on explants of leaf, leaf cotyledone and hypocotyle in both species. The best strain was wt for hairy root induction in hypocotyle and leaf explants of T. foenum-graeceum and T. monantha. Significant quantitative differences were showed between shoot, root and hairy roots in both species. Protein content in root and hairy root of both species was significantly lower in comparison with shoot. Superoxide dismutase (SOD) and peroxidase (POX) activities in hairy roots of both species were higher as compared to other organs. The hairy roots of both species showed an ability to synthesize steroidal sapogenins. These results presented that hairy roots could be a suitable procedure for producing sapogenins compounds that have medicinal value in Trigonella.     

An experimental heat wave changes immune defense and life history traits in a freshwater snail

The predicted increase in frequency and severity of heat waves due to climate change is expected to alter disease dynamics by reducing hosts' ability to resist infections. This could take place via two different mechanisms: (1) through general reduction in hosts' performance under harsh environmental conditions and/or (2) through altered resource allocation that reduces expression of defense traits in order to maintain other traits. We tested these alternative hypotheses by measuring the effect of an experimental heat wave (25 vs. 15°C) on the constitutive level of immune defense (hemocyte concentration, phenoloxidase [PO]‐like activity, antibacterial activity of hemolymph), and life history traits (growth and number of oviposited eggs) of the great pond snail Lymnaea stagnalis. We also manipulated the exposure time to high temperature (1, 3, 5, 7, 9, or 11 days). We found that if the exposure to high temperature lasted <1 week, immune function was not affected. However, when the exposure lasted longer than that, the level of snails' immune function (hemocyte concentration and PO‐like activity) was reduced. Snails' growth and reproduction increased within the first week of exposure to high temperature. However, longer exposures did not lead to a further increase in cumulative reproductive output. Our results show that short experimental heat waves do not alter immune function but lead to plastic responses that increase snails' growth and reproduction. Thus, although the relative expression of traits changes, short experimental heat waves do not impair snails' defenses. Negative effects on performance get pronounced when the heat waves are prolonged suggesting that high performance cannot be maintained over long time periods. This ultimately reduces the levels of defense traits.     

不同发酵茶中优势真菌的分离鉴定及产消化酶活性比较

目的 分离鉴定云南普洱茶、广州小青柑、广西六堡茶和湖南熙茯茶中的主要真菌,并探讨其产消化酶活性。方法 采用平板涂布法分离不同发酵茶中的真菌,通过其ITS序列进行分子鉴定;利用平板透明圈法测定不同真菌的产淀粉酶、蛋白酶、纤维素酶和脂肪酶活性。结果 从4种发酵茶中共分离出8种真菌,其中,在云南普洱茶中分离出2种真菌,分别为篮状菌（Talaromyces. sp.）和T. variabilis;广州小青柑中分离出3种真菌,分别为阿曲霉（Aspergillus amstelodami）、烟曲霉（A. fumigatus）和绳状篮状菌（T. funiculosus）;广西六堡茶中分离出2种真菌,分别为黑曲霉（A. niger）和冠突曲霉（A. cristatus）;湖南熙茯茶中仅分离出谢瓦曲霉（A.chevalieri）。其中Talaromyces. sp.、T. variabilis、A. niger、A.amstelodami、A. fumigatus、T. funiculosus有产纤维素酶活性,Talaromyces. sp.、T. variabilis、A. cristatus、A. fumigatus、T. funiculosus有产淀粉酶活性,Talaromyces. sp.、T. variabilis、A. niger、A. fumigatus、T. funiculosus有产蛋白酶活性,A. niger有产脂肪酶活性。在8种真菌中,T. variabilis、烟曲霉和绳状篮状菌可同时产纤维素酶、淀粉酶和蛋白酶;黑曲霉能同时产纤维素酶、蛋白酶和脂肪酶;冠突曲霉仅有产淀粉酶活性;阿曲霉仅有产纤维素酶活性。通过比较不同真菌的产酶活性表明,烟曲霉的产蛋白酶活性能力最强;Talaromyces sp.的产纤维酶活性能力最强;Talaromyces. sp.和绳状篮状菌的产淀粉酶活性最强。结论 发酵茶的真菌以曲霉菌属Aspergillus、散囊菌属Eurotium和篮状菌属Talaromyces为主,多数真菌具有产消化酶活性,这些酶可能在茶叶发酵过程中起重要作用,并影响发酵茶叶的品质。     

Response of digestive gland cells of freshwater mussel Unio tumidus to phenolic compound exposure in vivo

The exposure of freshwater mussels Unio tumidus to phenolic compounds (tannic, ellagic and gallic acid) in vivo caused changes in proteins and DNA function of digestive gland cells. The mussels were exposed to various concentrations of tested polyphenols (60, 200 and 500 microM) for 24 and 48 h and their antioxidant and pro-oxidant effects were determined. The number of SH-groups was quantified spectrophotometrically using Ellman's reagent. Oxidative modification of proteins increased in the digestive gland cells in a dose- and time-dependent manner. The level of nuclear DNA damage was investigated using the comet assay. The results revealed that polyphenolic acids induce single and double-strand breaks in DNA. The highest changes were observed for tannic and gallic acids and the smallest ones for ellagic acid. 1h of DNA repair process was also studied using the same method. The data obtained in this experiment demonstrate that the most effective DNA repair occurs in the cells exposed to phenolic compounds for 24h. A longer incubation (up to 48 h) does not decrease the capacity of the repair mechanism. The antioxidant activity of the tested phenols was analyzed spectrofluorimetrically using a fluorescence probe DCFH-DA (dichlorofluorescein-diacetate). The experimental data showed that the tested acids can act as antioxidants when used at higher doses (200 and 500 microM) against the reactive oxygen species present in the digestive gland cells. The most effective was ellagic acid, also applied at the smallest dose of 60 microM, in comparison with tannic and gallic acids. In conclusion, our results demonstrate that chosen water-soluble polyphenols, which are located in various plant tissues and are also found in the aquatic environment, can influence organisms living in the water. They can be exposed to these chemicals that cause morphological alterations and changes in certain physiological processes in their organs (i.e. digestive gland cells of bivalve molluscs).