Microbiology     

Mitchell R 《Science (New York, N.Y.)》1982,215(4529):157

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An evolutionarily conserved mechanism delimiting SHR movement defines a single layer of endodermis in plants   总被引：2，自引：0，他引：2  

Cui H  Levesque MP  Vernoux T  Jung JW  Paquette AJ  Gallagher KL  Wang JY  Blilou I  Scheres B  Benfey PN 《Science (New York, N.Y.)》2007,316(5823):421-425

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The Air noncoding RNA epigenetically silences transcription by targeting G9a to chromatin   总被引：1，自引：0，他引：1  

Nagano T  Mitchell JA  Sanz LA  Pauler FM  Ferguson-Smith AC  Feil R  Fraser P 《Science (New York, N.Y.)》2008,322(5908):1717-1720

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TDP-43 mutations in familial and sporadic amyotrophic lateral sclerosis   总被引：1，自引：0，他引：1  

Sreedharan J  Blair IP  Tripathi VB  Hu X  Vance C  Rogelj B  Ackerley S  Durnall JC  Williams KL  Buratti E  Baralle F  de Belleroche J  Mitchell JD  Leigh PN  Al-Chalabi A  Miller CC  Nicholson G  Shaw CE 《Science (New York, N.Y.)》2008,319(5870):1668-1672

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disorder characterized pathologically by ubiquitinated TAR DNA binding protein (TDP-43) inclusions. The function of TDP-43 in the nervous system is uncertain, and a mechanistic role in neurodegeneration remains speculative. We identified neighboring mutations in a highly conserved region of TARDBP in sporadic and familial ALS cases. TARDBPM337V segregated with disease within one kindred and a genome-wide scan confirmed that linkage was restricted to chromosome 1p36, which contains the TARDBP locus. Mutant forms of TDP-43 fragmented in vitro more readily than wild type and, in vivo, caused neural apoptosis and developmental delay in the chick embryo. Our evidence suggests a pathophysiological link between TDP-43 and ALS.  相似文献   

Role for the membrane receptor guanylyl cyclase-C in attention deficiency and hyperactive behavior     

Gong R  Ding C  Hu J  Lu Y  Liu F  Mann E  Xu F  Cohen MB  Luo M 《Science (New York, N.Y.)》2011,333(6049):1642-1646

Midbrain dopamine neurons regulate many important behavioral processes, and their dysfunctions are associated with several human neuropsychiatric disorders such as attention deficit hyperactivity disorder (ADHD) and schizophrenia. Here, we report that these neurons in mice selectively express guanylyl cyclase-C (GC-C), a membrane receptor previously thought to be expressed mainly in the intestine. GC-C activation potentiates the excitatory responses mediated by glutamate and acetylcholine receptors via the activity of guanosine 3',5'-monophosphate-dependent protein kinase (PKG). Mice in which GC-C has been knocked out exhibit hyperactivity and attention deficits. Moreover, their behavioral phenotypes are reversed by ADHD therapeutics and a PKG activator. These results indicate important behavioral and physiological functions for the GC-C/PKG signaling pathway within the brain and suggest new therapeutic targets for neuropsychiatric disorders related to the malfunctions of midbrain dopamine neurons.  相似文献   

Venipuncture Techniques in Pet Rodent Species     

Sandra Mitchell DVM  Dip. ABVP 《Journal of Exotic Pet Medicine》2011,20(4):284-293

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Serum chemistry comparisons between captive and free-ranging giraffes (Giraffa camelopardalis)     

Schmidt DA  Barbiers RB  Ellersieck MR  Ball RL  Koutsos EA  Griffin ME  Grobler D  Citino SB  Bush M 《Journal of zoo and wildlife medicine》2011,42(1):33-39

Serum chemistry analyses were compared between captive and free-ranging giraffes (Giraffa camelopardalis) in an attempt to better understand some of the medical issues seen with captive giraffes. Illnesses, including peracute mortality, energy malnutrition, pancreatic disease, urolithiasis, hoof disease, and severe intestinal parasitism, may be related to zoo nutrition and management issues. Serum samples were collected from 20 captive giraffes at 10 United States institutions. Thirteen of the captive animal samples were collected from animals trained for blood collection; seven were banked samples obtained from a previous serum collection. These samples were compared with serum samples collected from 24 free-ranging giraffes in South Africa. Differences between captive and free-ranging giraffes, males and females, and adults and subadults were analyzed by using a 2 x 2 x 2 factorial and Fisher's least significant difference for mean separation; when necessary variables were ranked and analyzed via analysis of variance. Potassium and bilirubin concentrations and alanine aminotransferase (ALT) activities were different between captive and free-ranging giraffes, but all fell within normal bovid reference ranges. The average glucose concentration was significantly elevated in free-ranging giraffes (161 mg/dl) compared with captive giraffes (113 mg/dl). All giraffes in this study had glucose concentrations higher than bovine (42-75 mg/ dl) and caprine (48-76 mg/dl) reference ranges. Differences were also seen in lipase, chloride, and magnesium though these findings are likely not clinically significant. There were no differences detected between sexes. Adults had higher concentrations of potassium, total protein, globulins, and chloride and higher gamma glutamyltransferase activities, whereas subadults had higher concentrations of phosphorus. Within the captive group, nonimmobilized animals had higher concentrations of total protein and globulins. Captive giraffe diets need further investigation to determine if the differences seen in this study, especially glucose and bilirubin concentrations and ALT activities, may result in some health problems often seen in captive giraffes.  相似文献   

Diallyl-disulphide to reduce the numbers of sclerotia of Sclerotium cepivorum in soil     

Andrew R. Entwistle  Peter R. Merriman  Herbie L. Munasinghe  Patricia Mitchell 《Soil biology & biochemistry》1982,14(3):229-232

A single injection of 0.2 ml diallyl disulphide (DADS) at 0.156% (v/v) into soil containing naturally-produced sclerotia of Sclerotium cepivorum and maintained in the laboratory at 15°C stimulated sclerotial germination and reduced sclerotial numbers by 67%; ungerminated sclerotia remained viable. Higher concentrations of DADS had no additional effect except that at 20% (v/v), germination was slightly inhibited. A similar reduction in sclerotial numbers was obtained when the mixture of soil and sclerotia was exposed to DADS vapour. Four, monthly applications of DADS at 0.2 ml 0.15% (v/v) per application did not give a further reduction.The effect of DADS was temperature dependant, with a reduction in sclerotial numbers of 65 and 9% at 15 and 5°C respectively.  相似文献   

Deoxynivalenol and zearalenone residues in eggs of laying hens fed with a naturally contaminated diet: effects on egg production and estimation of transmission rates from feed to eggs     

Sypecka Z  Kelly M  Brereton P 《Journal of agricultural and food chemistry》2004,52(17):5463-5471

The potential for the Fusarium mycotoxins 4-deoxynivalenol (DON) and zearalenone (ZON) to enter the human food chain through contaminated eggs was assessed using a controlled feed study. Four groups of laying hens (eight in each group) were fed a diet that included differing amounts of naturally contaminated wheat containing DON ( approximately 20 mg kg(-1)) and ZON (0.5 mg kg(-1)). Eggs were collected and pooled from each group on a daily basis. Pooled samples were analyzed by liquid chromatography with mass spectrometry detection (LC-MS/MS). The method allowed DON, other type B trichothecenes, ZON, and its metabolites to be determined in a single multi-residue analysis. The selectivity of the MS/MS procedure allowed cleanup to be minimized (for DON, cleanup by immunoaffinity column was used) or eliminated (for ZON). The limits of detection of 0.01 microg kg(-1) for DON and 0.1 microg kg(-1) for ZON in eggs were lower than previously published methods. None of the samples analyzed had detectable levels of ZON or its metabolites. Although maximum levels of DON contamination (10 mg kg(-1) feed) were relatively high, no adverse effects were observed on egg production. On the basis of the determined DON levels in the hen's diet and the determined levels of DON in the corresponding eggs, transmission rates of 15 000:1, 18 000:1, and 29 000:1 for treatment levels 5, 7.5, and 10 mg DON kg(-1) feed, respectively, were found. These results show that, although eggs could be a human exposure route for DON, the levels are insignificant compared to the other sources, although the presence of metabolites of DON was not studied.  相似文献   

Managing lead exposure and toxicity in cow-calf herds to minimize the potential for food residues.     

Cheryl Waldner  Sylvia Checkley  Barry Blakley  Colleen Pollock  Becky Mitchell 《Journal of veterinary diagnostic investigation》2002,14(6):481-486

Lead poisoning is commonly diagnosed in cattle. In this study, 3 groups of cattle from different herds accidentally exposed to discarded lead batteries on pasture were intensively studied to determine the extent and severity of exposure. The losses from acute death due to lead toxicity were substantial in all the 3 study groups at 12%, 17%, and 4%. Blood samples were taken from all cattle around the time of the first diagnosis and then later in 2 of the 3 herds to monitor the change in lead concentrations over time. Asymptomatic lead toxicosis was observed in these herds. In these 3 groups, between 4% and 12% of asymptomatic cattle had blood lead concentrations consistent with acute lead poisoning (> 0.35 ppm), and between 7% and 40% of these asymptomatic animals were in the high-normal range (0.1-0.35 ppm). Because of the consistently high number of asymptomatic cattle with elevated lead levels, all cattle potentially exposed to a lead source should be tested before sale or slaughter to minimize the entry of lead into the food chain. The blood lead concentrations, which were monitored for months after the initial diagnosis, decreased slowly after the cattle were removed from the lead source. The prolonged retention of lead may be due to continued release and absorption of lead from metal particles in the reticulum or rumen. The mean reduction in the lead level was 0.046 ppm (95% CI, 0.017-0.075 ppm) every 30 days for these 2 herds. Using a single-component exponential model, the half-life of lead in the animals retested from Herds 1 and 2 was highly variable. The median half-life was 63 days (interquartile range, 34-107 days). One out of 8 pregnant heifers with high blood levels had a stillborn calf. There were no abortions or calf mortalities in this group. Blood samples were'collected from the calves around the time of birth. The concentrations of lead in the blood of the calves exposed in utero were low (0.010-0.095 ppm).  相似文献