Tracking the evolution of a hydrothermal event plume with a RAFOS neutrally buoyant drifter     

JE Lupton  ET Baker  N Garfield  GJ Massoth  RA Feely  JP Cowen  RR Greene  TA Rago 《Science (New York, N.Y.)》1998,280(5366):1052-1055

The migration and evolution of a deep ocean hydrothermal event plume were tracked with a neutrally buoyant RAFOS float. The float remained entrained in the plume for 60 days, and the plume vorticity was calculated directly from the anticyclonic motion of the float. Concentrations of suspended particles, particulate iron, and dissolved manganese in the plume did not decay significantly during the 60 days, which indicates that event plumes would be easily detectable a year after formation.  相似文献   

Near extinction of a large, widely distributed fish     

JM Casey  RA Myers 《Science (New York, N.Y.)》1998,281(5377):690-692

Are extinctions of marine vertebrates as rare and unlikely as current data indicate? Long-term research surveys on the continental shelf between the Grand Banks of Newfoundland and southern New England reveal that one of the largest skates in the northwest Atlantic, the barndoor skate (Raja laevis), is close to extinction. Forty-five years ago, research surveys on St. Pierre Bank (off southern Newfoundland) recorded barndoor skates in 10% of their tows; in the last 20 years, none has been caught, and this pattern of decline is similar throughout the range of the species.  相似文献   

The influence of site factors on the composition and structure of semi-natural mixed-species stands of beech (Fagus sylvatica), silver fir (Abies alba) and Norway spruce (Picea abies) in the Upper Draganul Watershed of North-West Romania     

Abrudan  IV; Mather  RA 《Forestry》1999,72(2):87-94

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Reference hematologic and plasma chemistry values of brown tree snakes (Boiga irregularis).     

E W Lamirande  A D Bratthauer  D C Fischer  D K Nichols 《Journal of zoo and wildlife medicine》1999,30(4):516-520

Reference hematologic and plasma chemistry values were determined from 103 blood samples collected from 53 clinically healthy brown tree snakes (Boiga irregularis). Female snakes had significantly higher mean plasma values for total solids, total protein, calcium (Ca), phosphorus (P), uric acid, and blood monocyte percentage than did males, whereas males had significantly higher mean plasma fibrinogen values. The variances for hematocrit, monocyte percentage, azurophil percentage, plasma total solids, plasma total protein, albumin, Ca, and P also differed significantly between sexes. The higher mean values and greater variances for plasma total protein, plasma total solids, Ca, and P in the female snakes were probably associated with yolk synthesis and accumulation.  相似文献   

Grasslands in ‘Old World’ and ‘New World’ Mediterranean‐climate zones: past trends,current status and future research priorities          下载免费PDF全文

C. Porqueddu  S. Ates  M. Louhaichi  A. P. Kyriazopoulos  G. Moreno  A. del Pozo  C. Ovalle  M. A. Ewing  P. G. H. Nichols 《Grass and Forage Science》2016,71(1):1-35

Despite their ecological, economic and social importance, grasslands in areas with Mediterranean climates continue to receive limited scientific, political and media attention. The main objectives of this review are to compare and contrast dryland grasslands in the ‘Old World’ regions of the Mediterranean basin (southern Europe, western Asia and North Africa) with those of ‘New World’ regions with Mediterranean climates (Australia and Chile) and to identify common research priorities. The common characteristics and differences in climate, soils, native vegetation, importance of the livestock sector and the socio‐economic background for the different Mediterranean environments are examined. Past trends and the current status of temporary and permanent Mediterranean grasslands are also described. Some common issues between these regions are as follows: (i) adaptation to climate change; (ii) increasing persistence and drought survival of both annual and perennial species; (iii) the important role of forage legumes; (iv) maintaining grassland plant diversity; and (v) improved ecosystem services, such as carbon sequestration, control of soil erosion and wildfires, and preservation of both wild and domestic biodiversity. The favourable climate in these regions, which allows year‐round grazing and the growth of legumes, should be exploited to improve the sustainability of grassland‐based, extensive farming systems and the quality of their animal products, while at the same time improving ecosystem services. The decreasing support for grassland research and development programmes requires increased international scientific and technical cooperation among the few institutions operating in the different Mediterranean‐climate areas of the World to provide innovative and sustainable solutions to farmers.  相似文献   

Tetraoxanes as a new class of efficient herbicides comparable with commercial products          下载免费PDF全文

Raphael C Cusati  Luiz CA Barbosa  Célia RA Maltha  Antônio J Demuner  Alberto Oliveros‐Bastidas  Antônio A Silva 《Pest management science》2015,71(7):1037-1048

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Transduction and Transplantation of Spermatogonia into the Testis of Ram Lambs through the Extra-testicular Rete     

JR Rodriguez-Sosa  JD Silvertown  RA Foster  JA Medin  A Hahnel 《Reproduction in domestic animals》2009,44(4):612-620

Spermatogonial transplantation will provide a new way to study spermatogenesis in domestic animals, disseminate male genetics and produce transgenic animals, if efficiency can be improved. We evaluated a 'surgical' method for transplanting donor cells into testes of ram lambs, where the head of the epididymis is reflected, and a catheter introduced into the extra-testicular rete testis. We also tested transduction of ram spermatogonia with a lentiviral (LV) vector as a means to identify permanent colonization, and introduce genes into donor cells. Eight ram lambs, 11- to 13-week olds, were the recipients: in five, spermatogonia were injected into one testis, and the contralateral testis was an un-manipulated control: in two, spermatogonia were injected into one testis and the contralateral was sham-injected: in one, both testes were injected. Six lambs received spermatogonia labelled with a cell-tracking dye and these were collected 1 or 2 weeks after transplantation; three lambs received spermatogonia transduced with a LV vector driving the expression of enhanced Green Fluorescence Protein and these were collected after 2 months. Donor cells were detected by immunohistochemistry in tubules of seven of nine recipient testes. Approximately 22% of tubule cross-sections contained donor cells immediately after transplantation, and 0.2% contained virally transduced cells 2 months after transplantation. The onset of spermatogenesis was delayed, and there were lesions in both injected and sham-injected testes. Despite the effects of the surgery, elongated spermatids were present in one recipient testis 2 months after surgery. The results suggest that, after modifying the surgical and transduction techniques, this approach will be a means to produce good colonization by donor spermatogonia in sheep testes.  相似文献   

Isolation of Canine Mammary Cells With Stem Cell Properties and Tumour-Initiating Potential     

C Cocola  P Anastasi  S Astigiano  E Piscitelli  P Pelucchi  L Vilardo  G Bertoli  M Beccaglia  MC Veronesi  S Sanzone  O. Barbieri  RA Reinbold  GC Luvoni  I Zucchi 《Reproduction in domestic animals》2009,44(S2):214-217

Recent data suggest that mammary carcinogenesis may be driven by cancer stem cells (CSCs) derived from mutated adult stem cells, which have acquired aberrant cell self-renewal or by progenitor cells that have acquired the capacity for cell self-renewal. Spontaneous mammary cancers in cats and dogs are important models for the understanding of human breast cancer and may represent alternative species model systems that can significantly contribute to the study of human oncogenesis. With the goal of identifying markers for isolating human breast CSCs, we have generated a canine model system to isolate and characterize normal and CSCs from dog mammary gland. Insight into the hierarchical organization of canine tumours may contribute to the development of universal concepts in oncogenesis by CSCs. Cells with stem cell properties were isolated from normal and tumoural canine breast tissue and propagated as mammospheres and tumourspheres in long-term non-adherent culture conditions. We showed that cells obtained from spheres that display self-renewing properties, have multi-lineage differentiation potential, could generate complex branched tubular structures in vitro and form tumours in NOD/SCID mice. We analysed these cells for the expression of human stem and CSC markers and are currently investigating the tumour-initiating properties of these cells and the hierarchical organization of normal and neoplastic canine mammary tissue.  相似文献   

Conversion of starch from dry common beans (Phaseolus vulgaris L.) to ethanol     

Nancy N. Nichols  Nongnuch SutivisedsakBruce S. Dien  Atanu BiswasWilliam C. Lesch  Michael A. Cotta 《Industrial Crops and Products》2011,33(3):644-647

Dry common beans (Phaseolus vulgaris L.) were evaluated for potential conversion of starch to ethanol. Eight varieties of beans with average starch content of 46% (db) were assayed in a laboratory-scaled process based upon the commercial corn dry grind fermentation process. Ethanol yield was 0.43-0.51 g ethanol/g glucose (0.19-0.23 g ethanol/g beans). The average ethanol yield for the eight bean types was 92% of maximum theoretical yield, demonstrating that starch from beans could be efficiently converted to ethanol. Ethanol concentration obtained from 20% (w/w) solids loading was 3.5-4.4% (w/v). The residual fermentation solids contained, on a dry basis, 37.1-43.6% crude protein, 10.8-15.1% acid detergent fiber and 19.1-31.3% neutral detergent fiber.  相似文献   

Commercially Available Enzyme‐Linked Immunosorbent Assay and Polymerase Chain Reaction Tests for Detection of Feline Immunodeficiency Virus Infection          下载免费PDF全文

J. Nichols  H.Y. Weng  A. Litster  C. Leutenegger  L. Guptill 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2017,31(1):55-59

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