Effects of relative humidity, light intensity and photoperiod on the colony development of Erysiphe sp. on Rhododendron     

D. M. Kenyon †  G. R. Dixon  S. Helfer 《Plant pathology》2002,51(1):103-108

Growth and reproduction by powdery mildew pathogens is generally inhibited by decreasing relative humidity. With Erysiphe sp. on Rhododendron cv. Elizabeth, the initial stages of colony development were adversely affected by reducing the relative humidity from 100% to 70 and 85%. No significant effects on secondary or tertiary hyphal development were detected. Light intensity and photoperiod both had considerable effect on the induced resistance response of the host. Over the initial 5 days of colonization there were no significant differences between any of the treatments. After 13 days, however, expansion of fungal colonies at 180 photosynthetic active radiation (PAR) was limited solely to the area initially infested by primary hyphae. By comparison, in colonies grown at 80 PAR regardless of day length, secondary and tertiary hyphae had extended beyond the area first colonized. These effects resulted in differing morphologies, small colonies of densely packed hyphae formed at 180 PAR compared with open spreading colonies at 80 PAR.  相似文献   

Organic zinc and copper supplementation on antioxidant protective mechanism and their correlation with sperm functional characteristics in goats          下载免费PDF全文

M Narasimhaiah  A Arunachalam  S Sellappan  VK Mayasula  PR Guvvala  SK Ghosh  V Chandra  J Ghosh  H Kumar 《Reproduction in domestic animals》2018,53(3):644-654

Trace minerals feeding had significant effects on sperm production and fertility with better absorption and proper utilization within the body for optimum reproductive function. Several studies have shown that more influenced trace elements in the diets of animals are copper (Cu) and zinc (Zn). Bucks showing deficiency of this mineral might affect the quality of semen production which in turn would affect the fertility. This experiment was thus designed to test the effects of organic Cu and Zn supplementation on antioxidants enzyme activities and sperm functional attributes in fresh semen of bucks. Forty bucks (n = 40, Aged 5 months) were assigned to ten groups of four animals in each group, supplemented (for a period of 8 months) with different levels of organic Zn: 20 mg (T2), 40 mg (T3) and 60 mg (T4), organic Cu: 12.5 mg (T5), 25 mg (T6), 37.5 mg (T7) and combined organic Zn and Cu: 20 + 12.5 mg (T8), 40 + 25 mg (T9), 60 + 37.5 mg (T10), respectively, per kg dry matter and no additional mineral diet (control; T1). One hundred and sixty semen samples were collected through electro‐ejaculator and analysed for sperm quantity, quality, acrosome intactness and plasma membrane integrity and correlated with the catalase, superoxide dismutase, glutathione peroxidase and glutathione reductase enzyme activities in seminal plasma. The results indicated organic Cu and zinc supplemented bucks produced more sperm cells, had higher sperm concentrations, maintained higher (p < .01) sperm livability, plasma membrane and acrosome integrities, more motility and velocity. The increased antioxidant enzyme activities, reduced oxidative stress and lowered lipid peroxidation were positively correlated (p < .05) with the sperm functional attributes. In conclusion, organic Cu and Zn supplement to male goats showed protective roles against oxidative damage and maintained better fresh semen characteristics.  相似文献   

Morphological and Physiological Responses of Plantain (Plantago lanceolata) and Chicory (Cichorium intybus) to Water Stress and Defoliation Frequency          下载免费PDF全文

L. M. Cranston  P. R. Kenyon  S. T. Morris  N. Lopez‐Villalobos  P. D. Kemp 《Journal of Agronomy and Crop Science》2016,202(1):13-24

Plants are often subjected to periods of water stress. There are little data examining the effect of water stress on the forage species Plantago lanceolata and Cichorium intybus. In two pot experiments with P. lanceolata and C. intybus, morphological responses under optimum, dry, and very‐dry water treatments with weekly, fortnightly and 3‐weekly defoliation intervals and physiological responses under optimum and very‐dry water treatments were measured. A third experiment compared the rooting depths of P. lanceolata and C. intybus under field conditions. These findings suggest that both P. lanceolata and C. intybus can survive and continue to grow under water stress conditions with the main differences between the two species being attributable to morphological characteristics (root mass, taproot diameter and shoot mass fraction) rather than differences at a physiological level. Overall, the results suggest plantain may be more productive under moderate drought due to its greater shoot mass fraction, whereas chicory may be more productive and persistent under severe drought due to its greater root mass, taproot diameter and root depth under field conditions.  相似文献   

Lymphoproliferative diseases of fowl--high LDH levels associated with lymphoblastic leukemia (JM-V)     

N D Jones  A J Kenyon  C F Helmboldt  M Sevoian 《Avian diseases》1969,13(3):579-584

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Studies on Macaca mulatta infected with Rocky Mountain spotted fever.     

L S Sammons  R H Kenyon  G T Burger  W R Beisel  C E Pedersen 《American journal of veterinary research》1977,38(6):907-910

Acid-base alterations and changes in other selected serum constituents (free fatty acids, triglycerides, cholesterol, copper, cortisol, alpha1-acid glycoprotein, haptoglobin, and albumin) were measured during a study of Rocky Mountain spotted fever in 16 male rhesus macaques. Blood samples were taken from nonanesthetized macaques conditioned to repeated handling. Arterial pH increased and PCO2 decreased during the febrile period. Free fatty acids, triglycerides, copper, cortisol, alpha1-acid glycoprotein, and haptoglobin increased, whereas albumin decreased during the disease. Significant changes were not observed in arterial PO2. Cholesterol remained unchanged. The increase in arterial pH and decrease in PaCO2 indicated that respiratory alkalosis was present in macaques acutely affected with Rocky Mountain spotted fever.  相似文献   

Quantitative epidemiology of Banana Bunchy Top Virus Disease and its control   总被引：1，自引：0，他引：1  

M. C. Smith  J. Holt  L. Kenyon  & C. Foot 《Plant pathology》1998,47(2):177-187

Models of a banana bunchy top virus disease epidemic were developed to incorporate the two key features of an epidemic in a plantation in the Philippines: an exponential increase in disease incidence over 10 years, and a declining gradient of incidence from the outside edge of the plantation to the centre. A non-spatial model consisted of three difference equations to describe the numbers of latently infected and of infectious plants in the plantation and the size of the inoculum source outside the plantation. In a spatial model the outside portion of the plantation was divided into eight blocks running parallel to the outside edge. The dispersal gradient of the inoculum was assumed to be negative exponential. Analysis of the two models showed that for disease incidence to increase exponentially over time, the rate of disease progress could be dependent either on internal spread and roguing rate (proportion of diseased plants removed and replaced per unit time) or on the rate of increase of external inoculum pressure. The observed incidence gradient from the edge to the centre of the plot could be explained only if external inoculum dominated the parameters in the spatial model. This model was also used to explore a variable roguing rate across blocks. Simulations indicated that this may produce small gains over the adoption of a constant roguing rate over all blocks, but was risky because a shift of roguing emphasis only slightly too far towards the outside blocks can result in a dramatic increase in disease.  相似文献   

The Influence of Morphology,Follicle Size and Bcl‐2 and Bax Transcripts on the Developmental Competence of Bovine Oocytes     

THC De Bem  PR Adona  FF Bressan  LG Mesquita  MR Chiaratti  FV Meirelles  CLV Leal 《Reproduction in domestic animals》2014,49(4):576-583

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Reply     

LA CORNER  PR WOOD  JS ROTHEL 《Australian veterinary journal》1991,68(6):218-219

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Monensin controlled-release intraruminal capsule for control of bloat in pastured dairy cows   总被引：1，自引：0，他引：1  

LB LOWE  GJ BALL  VR CARRUTHERS†  RC DOBOS‡  GA LYNCH  PJ MOATE  PR POOLE†  SC VALENTINE 《Australian veterinary journal》1991,68(1):17-20

Monensin, a polyether ionophore antibiotic, is potentially an important agent for bloat relief in dairy cows grazing temperate legume-based pasture. A series of studies was undertaken to determine the effect of monensin, when delivered continuously in the rumen of lactating dairy cows by means of controlled-release capsules (monensin CRC). Such devices release approximately 300 mg/head/day for 100 d. A short-term pilot study made at Ruakura, New Zealand, tested monensin CRC in cows selected for high susceptibility to bloat and grazing lucerne (Medicago sativa) or red clover (Trifolium pratense). Treatment significantly reduced the incidence of bloat, while milk yield and protein yield were increased. There was no effect on fat yield. Following the pilot study, 6 large-scale field experiments involving a total of 368 lactating dairy cows, were made in Australia and New Zealand to confirm the effectiveness of monensin CRC for bloat control and to measure the effect of such treatment on milk production and composition. A severe bloat problem occurred in 2 experiments, mild bloat occurred in 2 others, while no visual signs of bloat were observed in the remaining 2 experiments. Bloat was significantly (P less than 0.05) reduced by monensin CRC treatment when data was pooled over the 4 experiments in which bloat occurred. Daily milk yield was increased in all experiments from a mean of 17.7 in untreated groups to 18.8 kg/head/day (P less than 0.05) in monensin CRC-treated cows. Protein percentage was not affected by treatment, while there was a decrease from 4.29 to 4.10% fat, although total fat yield was not affected.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Timing requirements for insulin/IGF-1 signaling in C. elegans     

Dillin A  Crawford DK  Kenyon C 《Science (New York, N.Y.)》2002,298(5594):830-834

The insulin/IGF-1 (where IGF-1 is insulin-like growth factor-1) signaling pathway influences longevity, reproduction, and diapause in many organisms. Because of the fundamental importance of this system in animal physiology, we asked when during the animal's life it is required to regulate these different processes. We find that in Caenorhabditis elegans, the pathway acts during adulthood, to relatively advanced ages, to influence aging. In contrast, it regulates diapause during development. In addition, the pathway controls longevity and reproduction independently of one another. Together our findings show that life-span regulation can be dissociated temporally from phenotypes that might seem to decrease the quality of life.  相似文献