Molecular structure of troponin C from chicken skeletal muscle at 3-angstrom resolution   总被引：19，自引：0，他引：19  

M Sundaralingam  R Bergstrom  G Strasburg  S T Rao  P Roychowdhury  M Greaser  B C Wang 《Science (New York, N.Y.)》1985,227(4689):945-948

The x-ray structure of chicken skeletal muscle troponin C (TnC), the Ca2+-binding subunit of the troponin complex, shows that the protein is about 70 angstroms long with an unusual dumbbell shape. The carboxyl and amino domains are separated by a single long alpha helix of about nine turns. Only the two high-affinity Ca2+-Mg2+ sites of the COOH-domain are occupied by metal ions resulting in conformational differences between the COOH- and NH2-domains. These differences are probably important in the triggering of muscle contraction by TnC. Also the structure of TnC is relevant in understanding the function of other calcium-regulated proteins, in particular that of calmodulin because of its strong similarity in amino acid sequence.  相似文献   

Dual infection of lambs with Trichostrongylus colubriformis and chlamydiae     

R.B. Grieve  R.C. Bergstrom  E.L. Belden 《Veterinary parasitology》1977,3(4):343-348

Lambs in one group were inoculated with chlamydiae and Trichostrongylus colubriformis larvae simultaneously; lambs in a second group were inoculated with chlamydiae after a T. colubriformis infection was established. Results were compared to those from groups inoculated with T. colubriformis only and chlamydiae only. There were no significant differences in fecundity associated with chlamydial inoculation. Packed cell volumes (PCVs) were depressed in groups inoculated with chlamydiae, and chlamydial antibody formation appeared to be inhibited when chlamydiae was superimposed on a T. colubriformis infection. Relatively few T. colubriformis adults were recovered in lambs inoculated with chlamydiae and T. colubriformis simultaneously.  相似文献   

C-reactive protein, tumor necrosis factor α, and interleukin-6 in dogs with pyometra and SIRS     

Boel A. Fransson  DVM  PhD  DACVS    Anne-Sofie Lagerstedt  DVM  PhD    Annika Bergstrom  DVM    Ragnvi Hagman  DVM  MSc  PhD    Jean S. Park  PhD    Boon P. Chew  DVM  PhD    Marc A. Evans  Claude A. Ragle  DVM  DACVS  DABVP 《Journal of Veterinary Emergency and Critical Care》2007,17(4):373-381

Objective: To determine the frequency of the systemic inflammatory response syndrome (SIRS) in canine pyometra and to evaluate the relationship between C‐reactive protein (CRP), tumor necrosis factor α (TNFα), interleukin‐6 (IL‐6), and SIRS. Design: Prospective clinical study. Setting: Veterinary teaching hospital. Animals: Fifty‐three clinical cases of canine pyometra and 19 healthy control bitches. Interventions: Upon admission to the veterinary hospital, history and physical examination findings, including previously defined clinical SIRS parameters, were documented. Blood samples were obtained for hematology and biochemical tests and for CRP, TNFα, and IL‐6 analysis. The diagnosis of pyometra was confirmed by histopathology of the uterus after ovariohysterectomy. After surgery, clinical SIRS parameters, length of hospitalization, and mortality were recorded. Measurements and main results: Pyometra dogs were grouped as SIRS positive (30/53; 57%) or SIRS negative (23/53; 43%). Logistic regression showed that CRP was the only parameter that significantly related to SIRS apart from the clinical criteria that define this syndrome. The mortality rate was low (2/53; 3.8%), and conclusions regarding association with SIRS could not be drawn. A positive SIRS status, high plasma CRP concentration, and high body temperature were variables that related to increased morbidity reflected by the length of hospitalization. Conclusions: SIRS was seen in 57% of canine pyometra cases and a positive SIRS status showed a positive association with prolonged hospitalization. The mortality rate was low (3.3%) among SIRS positive dogs, indicating that progression to multiple organ dysfunction syndrome (MODS) rarely occurs in surgically treated cases of pyometra. CRP was associated with SIRS and with prolonged hospitalization. Further studies of plasma CRP may be warranted in canine intensive care cases susceptible to development of SIRS and MODS.  相似文献   

Nachbarschaftsbezogene Analyse der Kronenraumbesetzung von Esche, Hainbuche und Winterlinde in einem artenreichen Laubmischwald (Nationalpark Hainich, Thüringen)     

Annika Frech  Christoph Leuschner  Marc Hagemeier  Dirk Hölscher 《European Journal of Forest Research》2003,122(1):22-35

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评估调质时间和温度对猪颗粒饲料淀粉糊化度和维生素沉积的影响     

Lewis LL  Stark CR  Fahrenholz AC  Bergstrom JR  Jones CK 《广东饲料》2015,24(5)

本论文研究了饲料加工的两个关键参数(调质温度和时间)对育肥猪颗粒饲料淀粉糊化度和维生素沉积的影响。日粮配方为含30%干酒糟及其可溶物的玉米-豆粕型基础日粮。整个试验中配方保持不变。本试验采用2×3双因子设计,调质温度分别为77℃和88℃,调质时间分别15秒、30秒和60秒。此外,本试验还设置一个对照组,对照组饲料不采用调质制粒工艺,而是采用粉料饲喂。因此,本试验共有7个处理组。采集调质后制粒前(热干粉)、制粒后冷却前(热制粒)、以及制粒冷却后(冷制粒)的样品,并分析这三种样品的总淀粉率、淀粉糊化  相似文献   

Prevalence of ophthalmic disease in blue‐eyed horses     

B. E. Bergstrom  A. L. Labelle  M. E. Pryde  R. E. Hamor  K. E. Myrna 《Equine Veterinary Education》2014,26(8):438-440

A perception exists amongst referring veterinarians and the lay public that blue‐eyed horses have increased frequency of ocular disease. The aim of this retrospective study was to assess the prevalence of ocular disease in horses with blue or heterochromic eyes relative to those with brown eyes. The medical records of horses presenting to either the Comparative Ophthalmology services or Equine Medicine/Surgery services at 2 institutions were reviewed. Signalment, ocular and nonocular diagnoses were recorded. Ocular disease was divided into 4 categories: adnexa, cornea, intraocular/orbit and squamous cell carcinoma (SCC). Owners were contacted by telephone to confirm iris colour. Chi‐square analysis was used to compare group proportions. A total of 164 eyes of horses with ocular disease and 212 eyes of horses without ocular disease were included. Blue eyes were equally common in the ocular disease and nonocular disease groups (P = 0.265). There was no significant difference in the proportion of blue‐ and brown‐eyed horses when comparing the adnexal and corneal (P = 0.548), corneal and intraocular/orbit (P = 0.379) and adnexal and intraocular/orbit (P = 0.843) categories. A significant difference was detected in the proportion of blue‐eyed horses between the adnexal (P = 0.000), corneal (P = 0.033), intraocular/orbital (P = 0.000) and SCC categories, with a higher proportion of blue‐eyed horses in the SCC than in the other 3 groups. Horses with blue or heterochromic irides are more likely to develop ocular SCC than horses with brown irides, but are not more likely to have adnexal, corneal or intraocular/orbital disease or to be presented for evaluation of ophthalmic disease. Veterinarians should consider the results of this study when answering questions from the lay public regarding the predisposition of blue‐eyed horses to ocular disease.  相似文献   

Mixing methods – assessment of potential benefits for natural resources planning     

Tanja Myllyviita  Teppo Hujala  Annika Kangas  Kyle Eyvindson  Susanna Sironen  Pekka Leskinen 《Scandinavian Journal of Forest Research》2014,29(7):20-29

Multi-objective forest planning is a multi-methodological endeavor whose success largely depends on how well the combined use of different methods contributes to the goals of the planning. This review assessed the benefits of mixing methods in natural resources planning. A sample of 30 peer-reviewed research articles was analyzed using an evaluation framework, designed based on democracy and planning theories, and participatory planning literature, including four dimensions: transparency, flexibility, consensus building, and operability. According to analyses, mixing different types (i.e. qualitative and quantitative) of methods generally yields greater benefits than the combination of similar methods. The subsample of 12 planning cases that utilized simulation-optimization software (SOS) appeared operable and moderately transparent, whereas flexibility and consensus building were often lacking. In comparison to the wide scholarly discussion on multi-methodology and mixing methods, it was observed that successful mixing examples in natural resource planning are still scarce and there are weaknesses in bridging the methods together. There is an evident need to pursue and to better communicate the benefits of mixing. Some good mixing examples utilizing SOS provided evidence that forest planning processes would make an excellent venue for studying the benefits and caveats of using mixed methods.  相似文献   

The density dilemma: limitations on juvenile production in threatened salmon populations     

Annika W. Walters  Timothy Copeland  David A. Venditti 《Ecology of Freshwater Fish》2013,22(4):508-519

Density‐dependent processes have repeatedly been shown to have a central role in salmonid population dynamics, but are often assumed to be negligible for populations at low abundances relative to historical records. Density dependence has been observed in overall spring/summer Snake River Chinook salmon Oncorhynchus tshawytscha production, but it is not clear how patterns observed at the aggregate level relate to individual populations within the basin. We used a Bayesian hierarchical modelling approach to explore the degree of density dependence in juvenile production for nine Idaho populations. Our results indicate that density dependence is ubiquitous, although its strength varies between populations. We also investigated the processes driving the population‐level pattern and found density‐dependent growth and mortality present for both common life‐history strategies, but no evidence of density‐dependent movement. Overwinter mortality, spatial clustering of redds and limited resource availability were identified as potentially important limiting factors contributing to density dependence. The ubiquity of density dependence for these threatened populations is alarming as stability at present low abundance levels suggests recovery may be difficult without major changes. We conclude that density dependence at the population level is common and must be considered in demographic analysis and management.  相似文献   

A Major Gene for Resistance to Anthracnose Leaf Blight in Maize     

B. Badu-Apraku  V. E. Gracen  G. C. Bergstrom 《Plant Breeding》1987,98(3):194-199

The inheritance of the reaction of maize (Zea mays L.) to anthracnose leaf blight caused by Colletotrichum graminicola was studied in eight generations derived from a cross between a hypersensitively resistant inbred. LB–58, and a susceptible inbred, A632. The generations consisted of the two parents, F₁, F₂ backcrosses and the backcrosses-selfed, Chisquare analysis of the data for individual locations as well as across locations indicated that resistance at both the seedling and mature plant stages of development is conditioned by a single dominant gene, designated CgL. A study of the reactions of LB-58 in several hybrid combinations indicated that resistance was expressed in ail cast-s even though the expression of CgL gene was modified somewhat in different hybrid combinations.  相似文献   

Ammonium‐driven nitrification plays a key role in increasing Mn availability in calcareous soils     

Michael Dreyer  Merle Wichmann  Marie Rischen  Bruno M. Görlach  Annika Ehmke  Britta Pitann  Karl H. Mühling 《植物养料与土壤学杂志》2020,183(3):389-396

Background : Manganese deficiency often becomes a yield limiting factor, particularly on calcareous soils, even though the total soil manganese content is usually sufficient. Although it is known that acidifying N fertilizers can improve Mn availability, the reason of this effect is still unknown. Aim : Our aim was to investigate the effect of stabilized ammonium fertilizers as a tool to distinguish between physiological‐ and nitrification‐induced acidification. Method : Two pot experiments with Triticum aestivum L. and one soil incubation experiment using different nitrogen forms (CN = calcium nitrate, AN = ammonium nitrate, AS = ammonium sulfate, ATS = ammonium thiosulfate) with and without addition of nitrification inhibitors (DCD, Nitrapyrin, Piadin, DMPP) were conducted to examine the effect on Mn availability in the soil and Mn uptake by the plants at different development stages (EC 31 und 39). Results : With increasing fertilizer ${\mathrm{NH}}_4^{+}$ content a higher Mn concentration was detected: CN: 32 µg Mn g^?1 DM, AN: 39 µg Mn g^?1 DW, AS: 55 µg Mn g^?1 DM, ATS: 109 µg Mn g^?1 DM. The addition of a nitrification inhibitor resulted in a significantly lower rhizosphere pH compared to the non‐stabilized fertilizer. Surprisingly, the use of different nitrification inhibitors led to unchanged (CN, AN) or lower Mn concentrations of wheat. Especially in the ${\mathrm{NH}}_4^{+}$ treatments (AS and ATS), this negative effect was very evident (AS+DCD: 42 µg Mn g^?1 DM; ATS+DCD: 55 µg Mn g^?1 DM). Conclusions : Mn availability was enhanced by ongoing nitrification process rather than physiological acidification. Compared to other N forms, ammonium thiosulfate led to the highest Mn availability in bulk soil.  相似文献