Effect of gamma irradiation on food consumption, assimilation and digestive enzymes in Ephestia cautella (Walker) larvae

The effects of gamma irradiation on the consumption, digestion and utilization of food by 8-18-day-old larvae of Ephestia cautella treated as 1-day-old larvae with 80 Gy, and also on the activity of protease, amylase and invertase enzymes, were studied. Gamma irradiation decreased the amount of food consumed and digested by the treated larvae in comparison with un-irradiated ones. It also reduced assimilation efficiency which further reduced weight gain. Protease, amylase and invertase enzyme activity was adversely affected in all irradiated larvae. The results revealed a positive correlation between the activity of the digestive enzymes and the amount of food digested by the larvae.     

消化酶、消化吸收与饲料加工

动物对饲料的消化吸收是通过消化酶将蛋白质、淀粉和脂肪等物质分解成小分子低肽及氨基酸、麦芽糖、葡萄糖和短链脂肪酸等才被小肠吸收.消化酶对饲料的消化,不仅取决于酶的活性、浓度和添加量;还与温度、pH值、饲料颗粒大小、颗粒表面积大小和饲料熟化度有关,同时应考虑金属离子对消化酶活性抑制和激活的影响.对不同食性和不同生长期的动物...     

Assessment of eight rice cultivars flour for feeding resistance to Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) is an important pest of processed stored grains worldwide. Study of life history, feeding efficiency and digestive function of an insect on different host cultivars can indicate their resistance for the insect's population increase. Due to the economic importance of T. castaneum on stored rice flour, this research was aimed to investigate the life history, feeding indices and digestive enzymatic activity of T. castaneum on flour of eight rice cultivars (Ali-Kazemi, Dom-Siah, Fajr, Gilaneh, Gohar, Hashemi, Khazar, and Neda). A delay in the developmental time of T. castaneum was detected on cultivar Gohar. The lowest fecundity and egg fertility were observed on cultivar Gohar. Feeding indices of fourth instar larvae were the lowest on cultivars Gohar and Neda. The amylolytic activity of fourth instar larvae was the highest on cultivars Hashemi, Dom-Siah, Ali-Kazemi and Gilaneh, and the lowest on cultivar Gohar. Also, the highest and lowest proteolytic activities of fourth instar larvae were on cultivars Khazar and Hashemi, respectively. Significant correlations were detected between tested parameters of T. castaneum with starch and protein value of examined cultivars flour. The results of cluster analysis indicate that Dom-Siah, Hashemi and Ali-Kazemi are relatively susceptible cultivars, and other tested cultivars, especially Gohar, are relatively resistant cultivars for feeding of T. castaneum. The resistant rice cultivars could be further evaluated to identify secondary biochemicals that contribute to T. castaneum resistance.     

Biochemical changes induced by fenpropathrin in the sixth instar larvae of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

Sixth instar larvae of Tribolium castaneum were exposed to one of four sublethal concentrations i.e. 10, 20, 200 or 400 mg/L, of a synthetic pyrethroid, fenpropathrin, for 48 hr. The lactate dehydrogenase activity decreased 44, 15 and 10% after exposure to fenpropathrin at concentrations of 20, 200 and 400 mg/L respectively, while a significant increase was recorded in glutamate oxaloacetate transaminase (15, 16, 34 and 37%) and glutamate pyruvate transaminase (6, 20, 13 and 29%) activities respectively after exposure to 10, 20, 200 and 400 mg/L. The amylase and acid phosphatase activities remained unaffected. The trehalase activity increased 42, 72 and 149%, after 20, 200 and 400 mg/L, the isocitrate dehydrogenase activity increased 28 and 67% after 10 and 20 mg/L, white alkaline phosphatase activity increased 13 and 12% after 10 and 400 mg/L respectively. The weaker (10 and 20 mg/L) and stronger (200 and 400 mg/L) doses elicited two different types of responses. A dose of 20 mg/L resulted in increased soluble proteins (14%), lipids (49%), cholesterol (57%), RNA (18%), and DNA (32%) content per larva, while the stronger dose of 400 mg/L resulted in their decrease except for lipids. The total proteins, lipids and free amino acids content per larva were not affected by either concentration, while the glucose content per insect decreased with increasing concentration of fenpropathrin.     

Effect of linear density of inlay yarns on the structural characteristics of knitted fabric tube and pressure generation on cylinder

An important step in the digestion of wool by certain insect pests is the reductive cleavage of protein disulphide bonds to open the fibre for protease action. For larvae of the webbing clothes moth, Tineola bisselliella, two enzymes have been suggested as being involved in this process, cystine reductase and cysteine lyase/desulphydrase.

In the present study, cystine reductase is shown not to be present in T. bisselliellalarvae. An earlier study, showing that cysteine lyase/desulphydrase is present in these larvae, is confirmed and extended to demonstrate that the activity is localised to the gut of larvae. This activity is also present in the larval gut of another clothes moth, Tinea pellionella, but is absent from the gut of the carpet beetle, Anthrenus flavipes, suggesting that larvae of moths and beetles use different mechanisms to reduce the disulphide bonds of wool.     

In vitro influence of spices and spice-active principles on digestive enzymes of rat pancreas and small intestine

In vitro influence of 14 individual spices (curcumin, capsaicin, piperine, garlic, onion, ginger, mint, coriander, cumin, ajowan, fennel, fenugreek, mustard, and asafoetida) on the activities of digestive enzymes of rat pancreas and small intestine was examined by including them in the reaction mixture at two different concentrations. A majority of spices enhanced the activity of pancreatic lipase and amylase when they are directly in contact with the enzyme. It is inferred that this positive influence on the activity of enzymes may have a supplementary role in the overall digestive stimulant action of spices, besides causing an enhancement of the titres of digestive enzymes in pancreatic tissue.     

Maize hybrids affected nutritional physiology of the khapra beetle,Trogoderma granarium Everts (Coleoptera: Dermestidae)

The Khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae), is an important insect pest of stored cereals, grains and other stored products in Iran and some countries of the world. Nutritional indices and digestive enzymatic activity of fifth instar T. granarium were investigated on nine maize hybrids (704, AR 89, AS 71, AS 77, BC 678, KSC 703, PL 472, SC 704, and Simax) at 33 ± 1 °C, relative humidity of 65 ± 5%, and a photoperiod of 14: 10 (L: D) h. The highest and lowest food consumption by larvae was on AR 89 and BC 678, respectively. Fifth instar larvae fed on 704 had the highest efficiency of conversion of ingested food, and those fed on BC 678 showed the lowest relative growth rate. The larval growth index, standardized insect-growth index and fitness index were the highest when larvae were reared on PL 472, and the lowest when they were reared on BC 678. The highest proteolytic and amylolytic activity was on KSC 703, and the lowest activity was on BC 678. The results of this study indicated that BC 678 was an unsuitable hybrid for feeding of fifth instar T. granarium. Studying the nutritional physiology of T. granarium on different maize hybrids can be useful in identifying the anti digestive compounds of host grains, which can be expressed in genetically engineered crops to confer resistance to this key pest.     

In vitro influence of spices and spice‐active principles on digestive enzymes of rat pancreas and small intestine

In vitro influence of 14 individual spices (curcumin, capsaicin, piperine, garlic, onion, ginger, mint, coriander, cumin, ajowan, fennel, fenugreek, mustard, and asafoetida) on the activities of digestive enzymes of rat pancreas and small intestine was examined by including them in the reaction mixture at two different concentrations. A majority of spices enhanced the activity of pancreatic lipase and amylase when they are directly in contact with the enzyme. It is inferred that this positive influence on the activity of enzymes may have a supplementary role in the overall digestive stimulant action of spices, besides causing an enhancement of the titres of digestive enzymes in pancreatic tissue.     

Automatic, rapid screening of seed resistance in cowpea, Vigna unguiculata (L.) Walpers, to the seed beetle Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) using acoustic monitoring

The biomonitor technique was investigated as a rapid and automatic method for measuring the resistance of cowpea varieties to the seed beetle Callosobruchus maculatus. This technique measures the activity of internally feeding insect larvae by counting ultrasonic emissions produced as they feed. Activity throughout the development of C. maculatus larvae in known susceptible and resistant cowpea varieties was recorded. This showed details of the development of each larval instar, and showed clear differences between the resistant and susceptible cowpeas. A rapid method for comparing cowpeas was proposed in which the activity of larvae was recorded for 24 h starting 14 days after oviposition. Using this method, significant differences in activity were apparent between one susceptible and two resistant cowpea varieties. Further comparisons using a randomised block experimental design also showed a clear difference in activity between one susceptible and one known resistant cowpea variety. This experimental protocol took 21 days. It is suggested that the biomonitor offers a promising method for screening seeds for resistance to insect pests with a reduction in the time and effort required over conventional bioassay methods.     

Poly(ethylene glycol)-alpha-chymotrypsin complex catalytically active in anhydrous isooctane

Enzymatic catalysis in predominantly organic media has undergone rapid expansions, particularly over the past decade. There are numerous potential advantages in employing enzymes in organic media. However, there are some crucial defects in the native enzyme-catalyzed biocatalyses, such as a decrease in their reaction rate due to diffusional limitations of substrates. To overcome these defects, enzymes modified chemically with polymers and physically with surfactants, which were soluble in organic solvents, were often used. However, they had inherent drawbacks. On the other hand, the enzymes modified physically with polymers were found to be soluble and catalytically active in organic media. To date, however, the effect of the amount of added polymers on the enzyme activity has not been clarified, even though this may be an important factor governing the activity of polymer-enzyme complexes in organic media. In this study, we obtained a complex of an enzyme and a hydrophilic polymer by lyophilizing an aqueous solution containing a polymer and an enzyme. We found that the polymer-enzyme complex was catalytically active in organic media even when the molar ratio of polymer/enzyme in its preparation stage was unity, and that the activity of the polymer-enzyme complex increased with an increase in the molar ratio of polymer/enzyme, reached the maximum activity (ca. 7200-fold higher than that of the native enzyme suspended in organic media) and then gradually decreased.     

Antinutritional effects of the chitin-binding lectin from Microgramma vacciniifolia rhizome (MvRL) on Sitophilus zeamais

Sitophilus zeamais Motsch. (Coleoptera: Curculionidae) is one of the most common and destructive storage pests in the world and its control depends mostly on the utilization of synthetic pesticides. The hazards of synthetic chemicals to people and the environment, together with the development of resistance by the insects, stimulate the investigation of alternative methods. In the present study, we determined the effects of the ingestion of artificial diet containing the Microgramma vacciniifolia rhizome lectin (MvRL) on survival, feeding and nutrition of S. zeamais adults. MvRL was incorporated into the artificial diets at concentrations ranging from 10 to 130 mg/g. Mortality rate, ingested food and variation in the weight of the insects were determined after 7 days. In addition, the in vitro effects of MvRL on the activity of insect digestive enzymes were investigated. MvRL did not increase the mortality rates but disrupted the nutritional status of the insects since the biomass variation and efficiency in conversion of ingested food were negative. The lectin was able to inhibit in vitro β-glucosidase and α-amylase activities. In conclusion, MvRL showed anti-nutritional properties on S. zeamais adults, which may be due interference with digestive enzymes. MvRL may be useful as an additive or synergistic agent for reduced pest fitness by affecting the food conversion into biomass.     

The relationship between Plodia interpunctella (Hb.) (Lepidoptera, Phycitidae) and stored-grain fungi

The development of Plodia interpunctella, in shelled corn (maize) discouraged the growth of stored grain fungi, and slightly raised the moisture content of the infested corn. Mouldy corn, on the other hand, hindered the development of this insect. Fewer larvae reached the adult stage on mouldy corn and only after a prolonged developmental period; the adults produced were smaller in size and produced fewer eggs in their ovaries than those on mould-free corn. The more mouldy the corn the more it became unfavourable for the insect but this depended in part on the fungus species present. The relationship between this insect and the majority of stored grain fungi appeared to be antagonistic. An exceptional relationship was found with Aspergillus halophilicus, in plated cultures, which attracted the adult insect to lay its eggs and on this fungus larvae developed almost as normally as on mould-free corn.     

Microwaves to control Callosobruchus maculatus in stored mung bean (Vigna radiata)

Disinfestation of stored grains using microwaves can be an alternative to chemical methods for controlling insects in grains and pulses. Mung bean of 12% moisture content (m.c.) was infested with different life stages of the cowpea weevil (Callosobruchus maculatus) and exposed to 200, 300 or 400 W microwave power levels for 14, 28 and 42 s. One hundred percent insect mortality for all life stages (egg, young larva, old larva, pupa and adult) was achieved with exposure to 400 W power level for 28 s, which caused a surface temperature of mung bean of 68.1 °C. Eggs were the most susceptible and adults were the least susceptible life stages to microwave treatments. No significant difference was observed between mortality of larvae and pupae stages and their mortality was between eggs and adults. Mung bean temperatures increased and germination decreased with increased power level or exposure time.     

Deleterious effects of Myracrodruon urundeuva leaf extract and lectin on the maize weevil,Sitophilus zeamais (Coleoptera,Curculionidae)

Deterioration and degradation of grains by storage insect pests lead to economic losses of several billion dollars and affect food security. Sitophilus zeamais is responsible for pre- and post-harvest damages to maize. The high toxicity of synthetic insecticides and the development of resistance by insects to the chemicals currently used stimulate the investigation of plant-derived insecticides as new alternatives for pest control. In this study, we report the effects of diets containing Myracrodruon urundeuva leaf extract (10–150 mg/g) and lectin (MuLL; 3–150 mg/g) on the survival, feeding, and nutrition of the storage pest S. zeamais. The digestive enzyme activity in gut extracts from the insects reared on the leaf extract (25 mg/g) or MuLL (15 mg/g) diets was also evaluated. The leaf extract induced mortality (LC₅₀: 72.4 mg/g), while MuLL (30–150 mg/g) exerted strong feeding deterrence. The leaf extract and MuLL promoted the loss of biomass, as reflected in the negative values for relative biomass gain rates and efficiencies in converting ingested food. Protease, trypsin-like, acid phosphatase, and amylase activities in the insects reared on leaf extract or MuLL diets were significantly (P < 0.05) lower than those in the control insects. MuLL ingestion also significantly reduced (P < 0.05) endoglucanase and alkaline phosphatase activities. In conclusion, the leaf extract and MuLL have the potential for S. zeamais control by killing adults and preventing the use of a food source, respectively. The deleterious effects of the extract and lectin on S. zeamais may be linked to enzyme inhibition and consequent suppression of digestive processes.     

Rice cultivars affect fitness-related characteristics and digestive physiology of the rice weevil,Sitophilus oryzae (L.) (coleoptera: Curculionidae)

The rice weevil, Sitophilus oryzae (L.), is one of the main pests of rice and other stored grains. Due to the negative effects of synthetic pesticides on the environment and non-target organisms, more environmentally benign alternative control techniques are needed for controlling pests. In the present study, the development, reproduction, and digestive enzyme activity of Sitophilus oryzae (L.) were evaluated on 12 rice cultivars under laboratory conditions [28 ± 1 °C, 60 ± 5% RH, and a photoperiod of 16:8 (L: D) h]. Among tested rice cultivars, the developmental time of S. oryzae immature stages was the shortest on DomSiah (33.0 days), Hashemi var. Guilan (34.0 days) and Hashemi var. Mazandaran (34.0 days) and the longest on Neda (44.5 days). The highest fecundity was recorded for beetles reared on cultivars DomSiah (316.8 eggs), Hashemi var. Mazandaran (301.1 eggs), and Hashemi var. Guilan (293.3 eggs); and the lowest for beetles reared on cultivar Neda (147.0 eggs). The highest survival of immature stages was recorded on cultivars Hashemi var. Mazandaran (80.0%), AliKazemi (75.2%), DomSiah (73.6%), and Hashemi var. Guilan (71.0%) whereas those on cultivar Neda (25.3%) had the lowest survival. The female adults that developed from larvae reared on cultivars Neda, Govhar, and Fajr had the lowest body mass (67.7, 68.6, and 69.4 mg). Also, the males’ mass was the lowest on cultivars Neda, Fajr, Shiroudi, and Govhar (60.7, 62.2, 62.9 63.3 mg, respectively). The adults developed from larvae reared on cultivars Fajr and Neda had the lowest levels of α-amylase activity (1.77 and 1.64 mU/min/individual, respectively). Also, those reared on cultivar Neda had the lowest levels of protease activity (0.067 OD/min/individual). Results suggest cultivar Neda, as an unsuitable food for S. oryzae development that negatively affects the amylolytic and proteolytic activity of this pest, could be considered in the integrated management programs of this pest.     

Two-sex life table analysis and digestive physiology of Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae) on different barley cultivars

The life table parameters and digestive enzymatic activity of Sitotroga cerealella Olivier (Lepidoptera: Gelechiidae), an important insect pest of grains, were studied under laboratory conditions (25 ± 1 °C, relative humidity of 65 ± 5% and a photoperiod of 16: 8 (L: D) h). Seeds of ten barley cultivars including Bahman, CB-84-10, Fajr30, Makuyi, Nosrat, Yousof, 12A₁, 13A₁, 18A₁ and 19A₁ were used as host diet. S. cerealella showed the shortest developmental time and the highest survival and fecundity after feeding on cultivar 19A₁. The longest developmental time and the lowest fecundity were on cultivars Bahman and Fajr30, respectively. The gross and net reproductive rates and intrinsic rate of increase were the highest when S. cerealella was reared on cultivar 19A₁. However, a corresponding decrease in these parameters was observed on cultivar Fajr30. Fourth instar larvae fed on cultivar 19A₁ showed higher α-amylase activity than those fed on other barley cultivars. However, S. cerealella larvae exhibited no significant difference in proteolytic activity among barley cultivars. Correlation analyses showed that high correlations existed between the life table parameters and α-amylase activity on one side and particle size index on the other. It is suggested that nutritional quality, especially seed hardness, may be the major factor responsible for the susceptibility of barley cultivars to S. cerealella.     

Characterization of Multisubstrate Processes during Membrane Digestion. (Data and hypotheses on the interactions and autoregulation of digestive and transport processes)

The regularities of interactions of the main groups of substrates during membrane digestion, their mechanisms as well as physiological and possible clinical significance are characterized. Mono-, bi- and multisubstrate processes of the hydrolysis of proteins, fats, carbohydrates and phosphoric esters have been investigated using new experimental models. The authors show that the activity of enzymes ensuring membrane digestion is affected by various food substrates which do not serve as substrates for a given enzyme. The inhibitory and stimulating effects have been observed in the process of interactions between different groups of food substrates (for example, lipids and peptides) as well as within a single group of food substrates (for example, between different peptides, peptides and amino acids etc.). The existence of species, ontogenetic and organ characteristics of the processes of interactions at the stage of membrane hydrolysis is shown. The analysis of the mechanisms of interactions permits us to conclude that a number of enzymes accomplishing membrane digestion are allosterically regulated systems. The possible alterations in the regulatory properties of digestive enzymes in pathology are considered.     

高粱原花青素对生长育肥猪抗氧化、免疫以及养分消化率的影响

研究高粱原花青素(sorghum procyanidins,SPC)对生长育肥猪生长性能、养分消化率、消化酶活性、免疫力和抗氧化能力的影响。160头70日龄、平均体重为(31. 28±1. 12) kg的杜×长×大三元杂交猪,按照单因素完全随机设计分为4个组,分别饲喂玉米-豆粕基础日粮,以及基础日粮中添加100、150、200 mg/kg SPC。实验期为14周,生长期和育肥期各7周。在每个实验阶段开始和结束时称重,每天记录采食量,计算各阶段平均日增重(ADG)、平均日采食量(ADFI)和料重比(F/G)。在每个实验阶段的最后3 d,收集粪样测养分消化率。在每个实验阶段结束时,采血测血清抗氧化指数和免疫参数,同时,每个重复随机屠宰2头猪,取胰腺组织,测消化酶活性。结果表明,日粮添加SPC对生长育肥猪的生长性能没有显著的促进作用(P 0. 05)。在生长猪阶段,日粮添加150 mg/kg和200 mg/kg SPC显著降低了消化酶的活性,对养分消化率有降低的趋势。在育肥猪阶段,日粮添加150 mg/kg显著提高了粗蛋白的表观消化率(P 0. 05),200 mg/kg SPC显著地抑制了消化酶的活性(P 0. 05)。与对照组相比,不论是在生长期还是育肥期,添加150 mg/kg或200 mg/kg的SPC均显著地增强了猪血清谷胱甘肽过氧化物酶(GSH-Px)和超氧化物歧化酶(SOD)的活性以及血清总抗氧化能力(T-AOC)(P 0. 05),降低了血清丙二醛(MDA)浓度(P 0. 05),提高了猪血清IgG、IgM和白细胞介素2(IL-2)的浓度(P 0. 05)。总之,SPC有利于提高生长育肥猪抗氧化能力,增强免疫力,但是对于生长育肥猪的生长性能及养分消化率没有显著的促进作用,相反,高浓度的SPC甚至抑制了消化酶的活性,从而影响养分的消化利用。     

The effect of storage on ice and various freezing treatments on enzyme leakage in muscle tissue of rainbow trout (Oncorhynchus mykiss)

In order to study the biochemical changes in fish muscle during ice storage and freezing-thawing processes, the activities of certain marker enzymes in the cell interstitial fluid from muscle tissue of rainbow trout (Oncorhynchus mykiss) were measured. The enzymes analysed were: lysosomal α-glucosidase (E.C. 3.2.1.20), β-N-glucosaminidase (E.C. 3.2.1.30) and acid phosphatase (E.C. 3.1.3.2). The activity in centrifuged tissue fluid (CTF) was compared with the activity in total homogenate. When ice storage was varied between 3 and 14 days, it did not affect enzyme leakage into the CTF significantly. However, there was a distinct difference between fresh fish and fish iced even for only 1 day, which gave increased leakage of marker enzymes. When the ice-stored samples were subject to a freezing-thawing cycle they showed a marked increase in enzyme activity in the press juice. When the freezing process was varied so as to achieve different freezing rates, the slowest freezing rate caused the highest enzyme leakage.     

SOFTENING AND BIOCHEMICAL CHANGES OF SAPOTE MAMEY FRUIT (POUTERIA SAPOTA) AT DIFFERENT DEVELOPMENT AND RIPENING STAGES

We investigated some of the physicochemical and biochemical factors associated with flesh softening of sapote mamey fruit during development and ripening. The activities of pectinmethylesterase (PME), polygalacturonase (PG) and β‐galactosidase (β‐GAL) enzymes were measured in fruits harvested at different development stages, and postharvest in two production seasons. The textural changes were most noticeable at the preclimacteric stage in ripening fruit. The water‐soluble pectin (WSP) increased at a different rate than firmness decreased. No correlation between PG or PME activity and changes in firmness was observed in ripening fruits, though a low correlation was seen between β‐GAL activity and softening in climacteric stage. Greatest loss of firmness occurred in climacteric stage. Fruit pulp softening was not dependent on a single enzyme activity.