Validating census methods to measure changes in house mouse populations

BACKGROUND: Tracking and census baiting are two techniques that are commonly advocated for monitoring the size of mouse populations. However, currently these techniques are only able to provide an index of population size, rather than an assessment of absolute numbers. In this study the authors tested the reliability of both tracking (footprints left on tiles of fixed size) and census baiting as indices of population size, and sought to calibrate levels of activity and bait consumption under both semi‐natural and field conditions (inside farm buildings). RESULTS: Under semi‐natural conditions, census baiting produced more satisfactory population estimates than those derived from tracking activity. An initial field trial established that the optimum bait point density for this technique was 1 point per 2 m. Subsequent field trials demonstrated that the bait census technique offers a way to estimate the approximate size of stable populations of mice (population size = (mean daily bait consumption ‐ 36.3)/2.46). CONCLUSION: The results to date are sufficiently encouraging to support the use of this cost‐effective approach to monitoring mouse numbers in the type of habitats investigated in this study. © Crown copyright 2008. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.     

Histopathological diagnostics of liver amoebiasis in Cambodia

Results of histopathological examination of a solitary chronical amoebic abscess in the liver of a patient from Cambodia are described. The abscess was at a proliferously reparative phase and Entamoeba histolytica was detected at the border between the necrosis and inner wall of abscess, as well as in the proper non-specific granulation tissue of the inner layers of abscess capsule. A differential diagnosis of the amoebic abscess from similar parasitary or pseudoparasitary liver lesions and differential diagnosis of amoebae in histological sections are given. For orientation examinations of the liver tissue for the presence of amoebae the authors recommend the impregnation after Grocott and staining with Goldner's trichrome for a more detailed evaluation of histological sections.     

Histopathological changes associated with silverleaf syndrome in squash

Silverleaf syndrome on squash ( Cucurbita pepo ) is characterized by vein clearing, and leaf whitening, and has been associated with the presence of nymphs of Bemisia tabaci (sweetpotato whitefly), and the presence of two double-stranded RNAs (4·2 and 4·6 kb) in symptomatic leaves. However, the aetiology of the disorder remains unknown. Anatomical studies using transverse and paradermal sections from symptomatic leaves of C. pepo cv. Dixie showed turgescent, aligned adaxial epidermal cell layer, flat cuticle and the presence of sub-epidermal spaces. Histochemical studies failed to reveal any breakdown in the cellulose cell walls; however, the cuticular layer, the pectin layer and cellulose wall of epidermal cells formed a fiat compact structure. Some changes were observed in the lipid content, with the presence of lipid bodies near cell wall membranes. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of preparations of symptomatic squash leaves, partially purified by differential centrifugation, revealed a protein with a molecular mass of about 48 k Da that was not found in comparable preparations of asymptomatic leaves. This protein was localized by immunological staining in the spongy mesophyll cells and in the layer of bundle sheath associated with sieve elements and companion cells of the leaf phloem.     

A review of biochemical mechanisms of warfarin resistance in the house mouse

The biochemical mechanisms of warfarin resistance in the house mouse (Mus musculus L.) have not been fully investigated. In some populations of warfarin-resistant mice there is a reduction in sensitivity of hepatic vitamin K-epoxide reductase to inhibition by warfarin. This is similar to a proposed mechanism of anticoagulant resistance in the Norway rat (Rattus norvegicus Berk.). The same enzyme in other warfarin-resistant populations is, however, sensitive to warfarin inhibition. Other studies have indicated that detoxification may play a role in conferring warfarin resistance in house mice.     

烟粉虱感染白僵菌后的组织病理变化

病症观察表明,烟粉虱感染白僵菌96 h后虫体颜色变为深红色。组织切片观察表明,白僵菌处理后36 h,可在表皮下面观察到芽生孢子。48 h后可在体内观察到明显的菌丝段。60 h可以观察到菌丝入侵到脂肪体中,96 h发现内部组织器官病变,肌肉边界变得模糊不清,体内出现大量菌丝,120 h后菌丝突破体壁向外生长,132 h后形成菌丝层。     

Metabolism of O,S-dimethyl propionyl- and hexanoylphosphoramidothioate in the house fly and white mouse

The metabolism of O,S-dimethyl propionyl- and hexanoylphosphoramidothioate was investigated in the white mouse and house flies. Compared to the hexanoylphosphoramidothioate, the propionyl analog is approximately 35-fold more toxic to house flies and is 10-fold less toxic to mice. On a percentage basis, substantially larger amounts of methamidophos were detected in house flies treated topically with the propionylphosphoramidothioate than in flies treated with the hexanoyl derivative. The reverse was evident in the case of the mouse where much larger amounts of methamidophos were formed after oral treatment with the hexanoylphosphoramidothioate. Minor amounts of other metabolic products also were detected, including an unknown from the hexanoylphosphoramidothioate. Metabolism of the S-methyl moiety to carbon dioxide appeared to be a major pathway for metabolic degradation of both compounds in both the white mouse and house fly. The difference in toxicity of the two acylphosphoramidothioates to the mouse and house fly is attributed to difference in the amounts of methamidophos formed in the animals.     

玫烟色拟青霉对菜青虫的侵染及致病作用

采用扫描电镜和组织切片方法研究了玫烟色拟青霉(Paecilomyces fumosoroseus)对3龄菜青虫的侵染和致病作用。结果表明:玫烟色拟青霉可通过体壁侵染虫体。3龄菜青虫在接菌8h后,附着在虫体表面的孢子开始萌发,24h后菌丝即可穿透体壁进入血腔,48h后可见虫体内有部分菌丝体。侵入虫体内的菌丝对寄主组织没有选择性。菌丝首先在入侵的血腔中生长,然后侵入邻近的脂肪体和肌肉,随菌丝在虫体内的增殖,中肠、丝腺等相继被侵染。受侵的各组织器官均发生明显的病变,如体壁分离、脂肪体变形、溶解,肌纤维排列松散,中肠上皮细胞脱落并出现许多空泡等。     

Metabolism and toxicity of metribuzin in mouse liver

Metribuzin was hepatotoxic in mice when administered intraperitoneally (ip) at sublethal doses of 150 to 250 mg/kg. Four dose-dependent abnormalities were evident. Histopathological examination revealed a fulminant centrilobular hepatic necrosis. The serum glutamic-pyruvic transaminase (GPT) activity was elevated. The liver glutathione (GSH) content was almost completely depleted. There was extensive covalent binding of radiocarbon from [carbonyl-¹⁴C]metribuzin to liver proteins and also high blood levels of metribuzin fragments. Each of these four effects of metribuzin on the liver or blood was alleviated or blocked in mice pretreated with piperonyl butoxide (PB), which inhibits the cytochrome P-450-dependent monooxygenase. PB also reduced the lethality of metribuzin by three-fold. In contrast, pretreatment with diethyl maleate to suppress the liver GSH content increased the lethality of metribuzin by twofold. The hepatotoxicity and acute lethality of metribuzin were probably due to reactive intermediates which are normally detoxified by GSH conjugation. The principal urinary metabolites of metribuzin in mice and rats are mercapturic acids, which arise via metribuzin sulfoxide or deaminometribuzin sulfoxide reacting with GSH. Sulfoxidation therefore appears to activate metribuzin to an electrophilic metabolite which, in the absence of GSH, binds to tissue proteins producing hepatotoxicity.     

Metabolism of 2,2-dimethyl-2,3-dihydrobenzofuranyl-7 N-dimethoxyphosphinothioyl-N-methylcarbamate in the house fly,rat, and mouse

The metabolism of a selectively toxic derivative of carbofuran, 2,2-dimethyl-2,3-dihydrobenzofuranyl-7 N-dimethoxyphosphinothioyl N-methylcarbamate (PSC), was examined in the house fly, rat, and mouse. In house flies, PSC is metabolized mainly to carbofuran and related oxidation products containing the intact N-methylcarbamyl ester moiety. Degradation to phenolic products was the principal route of metabolism in rodents. The results indicate that the selective toxicity of PSC between insects and mammals is attributable to differing pathways of metabolism.     

Glutathione S-transferase in the house fly: Biochemical and genetic changes associated with induction and insecticide resistance

Kinetic parameters were measured for glutathione S-transferase, an enzyme important in metabolic resistance to insecticides, in one susceptible and two insecticide-resistant strains of the house fly (Musca domestica L.), and in untreated and chemically induced flies. Both resistant strains differed from the susceptible strain in apparent K_m values for the enzyme, while only one differed in apparent V_max. Two of the strains were inducible with phenobarbital; the third with 3-methylcholanthrene. Kinetic analysis indicated enzyme induction was associated with changes in K_m rather than V_max, and genetic experiments showed that most variation relating to K_m and V_max was controlled by chromosome II. Based on these results, both metabolic resistance and induction of enzyme activity were associated primarily with the production of different forms of glutathione S-transferase rather than more of the enzyme present in susceptible flies.     

Circadian changes in the activity of some esterases in house crickets and their effect on the inhibitory action of phorate

A culture of house crickets Acheta domisticus (L) was maintained under light-dark, 12:12 photoperiod. The activities of cholinesterase (ChE) and carboxylesterase (CarE) of rhythmic adults were assayed at different times of the day. Both enzymes showed a daily rhythmic pattern of activity. ChE had its highest activity level at 1200 hr, while CarE showed two peaks of activity, at 1200 and 2400 hr. The lowest level of activity for both enzymes was recorded shortly after the onset of darkness. The effect of these rhythmic fluctuations on the inhibitory action of phorate was studied. Insects were topically treated with a sublethal dose of phorate. Phorate application took place at different intervals to coincide with different magnitudes of enzymes activity. ChE inhibition did not differ significantly in relation to the time of phorate application, however, CarE inhibition was much higher when phorate was applied at the beginning of the dark phase. Inhibited ChE showed a rapid recovery only in insects treated in the light phase.     

Histopathological changes and the genesis of adiaspiromycomas in mice infected intraperitoneally with Emmonsia cresens Emmons et Jellison, 1960.

Following an intraperitoneal inoculation with a suspension of aleuries of the funtus Emmonsia crescens, characteristic adiaspiromycomas originate in the abdominal cavity; a generalisation of the infection was caused by lymphogenic and haematogenic dissemination. At first, fragments of the mycelium became implanted and started to grow on the peritoneum; these were quickly destroyed by a gradually increasing leukocytic reaction. In the first month of infection nodules were formed mainly on predisposed sites in the abdominal cavity. Inside these nodules we found aleuries in the granulation tissue and a necrotic centre enclosing the accumulated inoculum. Development was delayed in aleuries released from agar particles after their resorption and in aleuries originating from remnants of the inoculum. This accounted for an initial heterogeneity of spherules in the nodules. The original nodules fus-d and formed large fibrous adiaspiromycomas. In the following months atypical spherules produced in large numbers by minute, developmentally retarded, budding spherules from the zone bordering the centres, were found inside these cel layer succumbed to regressive changes. The viability of these large spherules was confirmed by a finding of live adiaspores even at as late a time as 19 months after infection.     

Effect of diethylstilbestrol treatment of the Levant vole female during lactation,on the reproduction of her female offspring

Reproduction of 105 females of Levant vole (Microtus guentheri), which ingested diethylstilbestrol (DES) with their mothers’ milk at the age of 0–12 days, and of 62 control females, was studied. In most cases ingestion of DES did not cause sterility, but delayed sexual maturity by 1.5–2 months. This delay was observed in all of the females which ingested DES when they were newborn and 1 day old, in 50% of those that received it at the age of 2 days, and in only 30–40% of those that received it at an older age. Ingestion of DES had no effect on litter size or sex ratio. The total pup production of females which were given DES through their mothers’ milk was about half that of control females.     

Diethylstilbestrol as a reproduction inhibitor in the Levante vole

Diethylstilbestrol (DES) at 0.019–0.025 mg/g body weight, fed with grain baits to Levante voles (Microtus guentheri [D. & A.]) of different age, sex and physiological condition, suppressed gestation for the first 10 days after mating. These doses, which are consumed voluntarily, also caused sterility in daughters of females which received DES at the end of pregnancy, and sterility or a significant delay (2–3 months) in sexual maturity of females which received it in their mother’s milk during the first days of life. DES had no significant effect on adult nonpregnant females or on males of any age, even if administered 3 days before mating.     

异色瓢虫成虫对温室几种常见害虫的取食偏嗜性初步研究

在直径90mm培养皿中进行了经饥饿处理的异色瓢虫成虫对同时存在的等数量桃蚜和温室白粉虱若虫、棉蚜和温室白粉虱若虫、西花蓟马和温室白粉虱若虫捕食偏嗜性研究.结果表明,在桃蚜和温室白粉虱若虫同时存在条件下,异色瓢虫成虫对其捕食更偏嗜桃蚜.但是,随着瓢虫饥饿时间延长,捕食选择性减低;在棉蚜和温室白粉虱若虫同时存在条件下,异色瓢虫成虫对其捕食较偏嗜棉蚜;在西花蓟马和温室白粉虱同时存在条件下,异色瓢虫成虫对其捕食更偏食西花蓟马.各试验中对温室白粉虱的捕食效果普遍较差.     

In vivo biochemical changes in liver and gill of Clarias batrachus during cypermethrin exposure and following cessation of exposure

The sublethal effect of a synthetic pyrethroid, cypermethrin on total protein, amino acids, ammonia, glycogen, and enzymes like aminotransaminases (AIAT, AAT), glutamate dehydrogenase, and glycogen phosphorylases (a and ab) was studied in physiological important tissues viz; liver and gill tissues of freshwater teleost air breathing fish, Clarias batrachus. The study was conducted during exposure of 1/3 (33%) of LC₅₀ concentration and followed by cessation of exposure. Thirty-six fish were exposed to 0.07 mg/L cypermethrin for 10 days. After 10 days, 18 fish were released to freshwater and kept in the same for 10 days (recovery group). Thirty-six fish were kept in freshwater as control batch. Protein content in liver tissues decreased at the end of 1st and 5th day followed by slight increase at the end of 10th day. Gill tissue showed statistical significant decrease (P < 0.001) in protein content during exposure period of 10 days. Recovery in protein content was observed to a large extent in both the tissues. Total free amino acids were increased in liver and gill tissues throughout the treatment period, recovery response was seen after cessation of exposure. Ammonia level was decrease in both the tissues throughout the exposure period except in liver tissue at the end of 1st day of exposure. Recovery response was exhibited by both the tissues. A decreased in glycogen content of liver tissue was observed during exposure period, gill tissue also showed decrease in glycogen at the end of 1st and 5th day followed by increase at the end of 10th day of exposure period. When the fish were transferred to freshwater, recovery in glycogen content was noted. The activity level of alanine, aspartate aminotransaminase, glutamate dehydrogenase, and phosphorylases (a, ab) was increased in both the tissues, followed by recovery response after released of fish into freshwater. The present study showed that cypermethrin caused alterations in certain biochemical mechanisms of C. batrachus. This fish indicated recovery response when transferred to cypermethrin free water.     

Oxidative metabolism of lindane and its isomers with microsomes from rat liver and house fly abdomen

Lindane and other hexachlorocyclohexane isomers produced 2,4,6-trichlorophenol as the major oxidative metabolite when incubated in the presence of NADPH under aerobic condition. A mechanism for the formation of 2,4,6-trichlorophenol is proposed, which includes direct oxygenation of the cyclohexane ring. The proposed mechanism is supported by data from studies of model chemical reactions of the pentachlorocyclohexanol isomers. Pathways leading to 1,2,4-trichlorobenzene, tetrachlorobenzene isomers, 2,4,5-trichlorophenol, and tetrachlorophenol isomers are discussed, and are considered to include the route through pentachlorocyclohexene and hexachlorocyclohexene. Reductive dechlorination of lindane under anaerobic condition was observed using microsomes and NADPH.