Estimating the outcrossing rate of Cyperus difformis using resistance to ALS-inhibiting herbicides and molecular markers     

A MEROTTO JR  M JASIENIUK†  & A J FISCHER† 《Weed Research》2009,49(1):29-36

Cyperus difformis (smallflower umbrella sedge) is an economically important weed of rice in California where its control has recently been complicated by the evolution of herbicide resistance. Knowledge of the mating system of this weed is needed to elucidate the dynamics of resistance evolution and to design mitigation strategies that delay its occurrence. The aim of this study was to estimate the outcrossing rate of C. difformis using molecular and phenotypic markers. Outcrossing rates were estimated in natural field populations using sequence-related amplified polymorphism (SRAP) molecular markers and in glasshouse and field experiments using resistance to the acetolactate synthase-inhibiting herbicide bensulfuron-methyl as a phenotypic marker. Using SRAP markers, the multilocus ( t _m) and average single-locus ( t _s) outcrossing rates varied from 0.014 to 0.025 and from 0.008 to 0.012, respectively, among natural weed populations in rice fields. Using resistance to bensulfuron-methyl as a genetic marker, the average C. difformis outcrossing rate estimated was 0.009 in the glasshouse and 0.0084 in the field. These results indicate that C. difformis is a highly self-fertilising species. Therefore, the primary mechanism by which genes for herbicide resistance can be transferred among C. difformis populations in different rice fields is probably seed dispersal. Weed management should emphasise prevention of seed production and dispersal to preclude the further spread and evolution of resistance in C. difformis .  相似文献   

Transplacental Transfer of Iron in the Water Buffalo (Bubalus bubalis): Uteroferrin and Erythrophagocytosis     

FTV Pereira  FC Braga  KC Burioli  JR Kfoury Jr  LJ Oliveira  PC Papa  AF Carvalho  CE Ambrósio  FW Bazer  MA Miglino 《Reproduction in domestic animals》2010,45(5):907-914

The objectives of this investigation were to understand transplacental transport of iron by secreted uteroferrin (UF) and haemophagous areas of water buffalo placenta and clarify the role(s) of blood extravasation at the placental‐maternal interface. Placentomes and interplacentomal region of 51 placentae at various stages of gestation were fixed, processed for light and transmission electron microscopy, histochemistry and immunohistochemistry. Haemophagous areas were present in placentomes collected between 4 and 10 months of pregnancy. Perl’s reaction for ferric iron was negative in placentomes, but positive in endometrial glands. Positive staining for UF indicated areas in which it was being taken up by phagocytosis and/or fluid phase pinocytosis in areolae of the interplacentomal mesenchyme, with little staining in endometrial stroma. Imunohistochemistry detected UF in trophectoderm of haemophagous regions of placentomes and in other parts of the foetal villous tree, but the strongest immunostaining was in the epithelial cells and lumen of uterine glands. Ultrastructural analyses indicated that erythrophagocytosis was occurring and that erythrocytes were present inside cells of the chorion that also contained endocytic vesicles and caveolae. Results of this study indicate that both the haemophagous areas of placentomes and the areolae at the interface between chorion and endometrial glands are important sites for iron transfer from mother to foetal‐placental tissues in buffalo throughout pregnancy.  相似文献   

The Quantum Event of Oceanic Crustal Accretion: Impacts of Diking at Mid-Ocean Ridges     

JR Delaney  DS Kelley  MD Lilley  DA Butterfield  JA Baross  WSD Wilcock  RW Embley  M Summit 《Science (New York, N.Y.)》1998,281(5374):222-230

Seafloor diking-eruptive events represent the irreducible, quantum events of upper oceanic crustal accretion. They record events by which a large portion of the oceanic crust has formed through geological history. Since 1993, the U.S. Navy's real-time Sound Surveillance System has allowed location of ongoing acoustic signatures of dike emplacement and basalt eruptions at ridge crests in the northeast Pacific. These diking-eruptive events trigger a sequence of related, rapidly evolving physical, chemical, and biological processes. Magmatic volatiles released during these events may provide nutrients for communities of subseafloor microorganisms, some of which thrive in high-temperature anaerobic environments. Many of the organisms identified from these systems are Archaea. If microorganisms can thrive in the water-saturated pores and cracks within deep, volcanically active portions of our planet, other hydrothermally active planets may harbor similar life forms.  相似文献   

A massive terraced village complex in chihuahua, mexico, 3000 years before present     

RJ Hard  JR Roney 《Science (New York, N.Y.)》1998,279(5357):1661-1664

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The structure of the upper atmosphere of mars: In situ accelerometer measurements from mars global surveyor   总被引：1，自引：0，他引：1  

GM Keating  SW Bougher  RW Zurek  RH Tolson  GJ Cancro  SN Noll  JS Parker  TJ Schellenberg  RW Shane  BL Wilkerson  JR Murphy  JL Hollingsworth  RM Haberle  M Joshi  JC Pearl  BJ Conrath  MD Smith  RT Clancy  RC Blanchard  RG Wilmoth  DF Rault  TZ Martin  DT Lyons  PB Esposito  MD Johnston  al et 《Science (New York, N.Y.)》1998,279(5357):1672-1676

The Mars Global Surveyor (MGS) z-axis accelerometer has obtained over 200 vertical structures of thermospheric density, temperature, and pressure, ranging from 110 to 170 kilometers, compared to only three previous such vertical structures. In November 1997, a regional dust storm in the Southern Hemisphere triggered an unexpectedly large thermospheric response at mid-northern latitudes, increasing the altitude of thermospheric pressure surfaces there by as much as 8 kilometers and indicating a strong global thermospheric response to a regional dust storm. Throughout the MGS mission, thermospheric density bulges have been detected on opposite sides of the planet near 90 degreesE and 90 degreesW, in the vicinity of maximum terrain heights. This wave 2 pattern may be caused by topographically-forced planetary waves propagating up from the lower atmosphere.  相似文献   

Enteric redmouth bacterium: comparison of isolates from different geographic areas     

G. L. BULLOCK  H. M. STUCKEY  E. B. SHOTTS  JR  † 《Journal of fish diseases》1978,1(4):351-356

Abstract. Characteristics of 18 strains of Yersinia ruckeri the causative agent of enteric redmouth disease, from a variety of hosts and a wide geographic range were compared. Except for variations in colonial morphology and in citrate, sorbitol, and trehalose reactions, the strains were morphologically and biochemically homogeneous. Sixteen strains reacted with antiserum against the first serotype reported, and one strain reacted with antiserum against a more recently reported serotype. One strain represented a third serotype. Evidence presented indicated that extension of the geographic range may not be entirely a result of the transport of carrier fish.  相似文献   

Social and financial aspects of the artisanal fisheries of Middle São Francisco River, Minas Gerais, Brazil     

S. A. Franco De Camargo  & M. Petrere JR 《Fisheries Management and Ecology》2001,8(2):163-171

The presence or absence of motorized boats, partnerships and multispecies catches characterize the fisheries of São Francisco River, Minas Gerais, Brazil. Fishing activity based on 109 interviews, carried out in the wet (high water: February and March) and dry (low water: July and August) seasons, with professional fishermen are described. Aiming to identify the fishery income components, a covariance model was proposed, with the income as the response variable, related to the factors: fishing ground; use of motorized or paddle boat; seasonality; presence of fishing assistant; and the following covariates: capture in weight in the week prior to the interview; fisherman experience in yrs; and distance (km) travelled for fishing. The results indicated that the main contributions to income were the absence of an engine (because of high price of the fuel), the absence of a partner (because of low capture) and the amount of fish caught by the fishermen.  相似文献   

Duration of Mycoplasma hyopneumoniae Infection in Gnotobiotic Pigs   总被引：3，自引：0，他引：3       下载免费PDF全文

N.R. Underdahl  G.A. Kennedy    A.S. Ramos  JR. 《The Canadian veterinary journal. La revue veterinaire canadienne》1980,21(9):258-261

Sixteen gnotobiotic pigs raised in flexible plastic isolators (four pigs per isolator) were inoculated with a culture of Mycoplasma hyopneumoniae. One pig was killed and underwent necropsy at weekly intervals for the following 16 weeks. Macroscopic lesions were observed in the lungs of 13 of 16 pigs and microscopic lesions were found in 14 of 16 pigs. Mycoplasma hyopneumoniae was cultured from the trachea or lungs from 10 of the 16 pigs. Scanning electron microscope studies showed areas of damage to the cilia, collections, of leucocytes and mucus, and mycoplasma in the trachea as well as the bronchi. These conditions were found in all the pigs seen at necropsy from nine to 16 weeks postinoculation and there was no evidence of noticeable regression or recovery during this 16 week period.  相似文献   

Chloramphenicol 4. Responsible topical use in ophthalmology     

JR BLOGG 《Australian veterinary journal》1991,68(1):8-9

Chloramphenicol has gained widespread use in the topical treatment of ocular infections. The rationale for this use was based on the ability of chloramphenicol to penetrate the cornea and enter the anterior segment, together with its broad spectrum of antimicrobial activity. However, routine use in corneal ulceration or keratitis is not desirable. Hypopyon, when present, is usually sterile. Concerns about human exposure to chloramphenicol and its recent prohibition of use in food-producing animals, raise the need to review its indications and discuss alternatives. The role of chloramphenicol in ocular therapeutics is examined in this article.  相似文献   

Treatment of virulent footrot with lincomycin and spectinomycin   总被引：1，自引：0，他引：1  

CM VENNING  MA CURTIS  JR EGERTON 《Australian veterinary journal》1990,67(7):258-260

A mixture of lincomycin and spectinomycin was investigated as a treatment for footrot in sheep. In a controlled clinical trial 92.5% of acute and chronic cases of virulent footrot were cured following a single intramuscular injection of a mixture containing 50 mg lincomycin and 100 mg spectinomycin/ml at a dose rate of 1 ml/10 kg bodyweight. No improvement in clinical response was observed in groups of sheep treated on 3 successive days with this dose rate nor in another group treated once at a dose rate 1 ml/3.3 kg bodyweight. Cure effectiveness of each of the 3 treatment groups relative to untreated controls was 89%, 95% and 95%. Efficacy of lincomycin/spectinomycin was compared with that of penicillin/streptomycin in the treatment of footrot on 2 farms in south western New South Wales. Assessments made 14 to 17 d after treatment showed that on one farm all 122 ewes treated with lincomycin/spectinomycin had recovered while 170 of 175 ewes treated with penicillin/streptomycin recovered in the same period. On the second farm 87 of 90 ewes treated with lincomycin/spectinomycin recovered, compared with 184 of 190 sheep in the same flock treated with penicillin/streptomycin. Supportive footbathing did not seem to improve the clinical response in either treatment group and the paring done was sufficient only to establish diagnosis and to remove grossly overgrown horn.  相似文献