Temporal dynamics of stem expansion and contraction in savanna trees: withdrawal and recharge of stored water     

Scholz FC  Bucci SJ  Goldstein G  Meinzer FC  Franco AC  Miralles-Wilhelm F 《Tree physiology》2008,28(3):469-480

Relationships between diel changes in stem expansion and contraction and discharge and refilling of stem water storage tissues were studied in six dominant Neotropical savanna (cerrado) tree species from central Brazil. Two stem tissues were studied, the active xylem or sapwood and the living tissues located between the cambium and the cork, made up predominantly of parenchyma cells (outer parenchyma). Outer parenchyma and sapwood density ranged from 320 to 410 kg m(-3) and from 420 to 620 kg m(-3), respectively, depending on the species. The denser sapwood tissues exhibited smaller relative changes in cross-sectional area per unit change in water potential compared with the outer parenchyma. Despite undergoing smaller relative changes in cross-sectional area, the sapwood released about 3.5 times as much stored water for a given change in area as the outer parenchyma. Cross-sectional area decreased earlier in the morning in the outer parenchyma than in the sapwood with lag times up to 30 min for most species. The relatively small lag time between dimensional changes of the two tissues suggested that they were hydraulically well connected. The initial morning increase in basal sap flow lagged about 10 to 130 min behind that of branch sap flow. Species-specific lag times between morning declines in branch and main stem cross-sectional area were a function of relative stem water storage capacity, which ranged from 16 to 31% of total diurnal water loss. Reliance on stored water to temporarily replace transpirational losses is one of the homeostatic mechanisms that constrain the magnitude of leaf water deficits in cerrado trees.  相似文献   

Removal of nutrient limitations by long-term fertilization decreases nocturnal water loss in savanna trees     

Scholz FG  Bucci SJ  Goldstein G  Meinzer FC  Franco AC  Miralles-Wilhelm F 《Tree physiology》2007,27(4):551-559

Under certain environmental conditions, nocturnal transpiration can be relatively high in temperate and tropical woody species. We have previously shown that nocturnal sap flow accounts for up to 28% of total daily transpiration in woody species growing in a nutrient-poor Brazilian Cerrado ecosystem. In the present study, we assessed the effect of increased nutrient supply on nocturnal transpiration in three dominant Cerrado tree species to explore the hypothesis that, in nutrient-poor systems, continued transpiration at night may enhance delivery of nutrients to root-absorbing surfaces. We compared nocturnal transpiration of trees growing in unfertilized plots and plots to which nitrogen (N) and phosphorus (P) had been added twice yearly from 1998 to 2005. Three independent indicators of nocturnal transpiration were evaluated: sap flow in terminal branches, stomatal conductance (g(s)), and disequilibrium in water potential between covered and exposed leaves (DeltaPsi(L)). In the unfertilized trees, about 25% of the total daily sap flow occurred at night. Nocturnal sap flow was consistently lower in the N- and P-fertilized trees, significantly so in trees in the N treatment. Similarly, nocturnal g(s) was consistently lower in fertilized trees than in unfertilized trees where it sometimes reached values of 150 mmol m(-2) s(-1) by the end of the dark period. Predawn gs and the percentage of nocturnal sap flow were linearly related. Nocturnal DeltaPsi(L) was significantly greater in the unfertilized trees than in N- and P-fertilized trees. The absolute magnitude of DeltaPsi(L) increased linearly with the percentage of nocturnal sap flow. These results are consistent with the idea that enhancing nutrient uptake by allowing additional transpiration to occur at night when evaporative demand is lower may avoid excessive dehydration associated with increased stomatal opening during the day when evaporative demand is high.  相似文献   

Effect of dietary crude-protein type on fertilization and embryo quality in dairy cattle   总被引：2，自引：0，他引：2  

T Blanchard  J Ferguson  L Love  T Takeda  B Henderson  J Hasler  W Chalupa 《American journal of veterinary research》1990,51(6):905-908

An experiment was conducted to determine whether balancing dietary crude protein for optimal rumen degradability would improve fertilization rate and quality of ova in lactating dairy cows. Thirty-eight Holstein cows in early lactation were fed 1 of 2 diets formulated to be isocaloric and isonitrogenous, containing 16% crude protein. Diet 1 contained 73% rumen degradable intake protein, whereas diet 2 contained 64% rumen degradable intake protein. The cows were induced to superovulate and were inseminated, and ova were recovered nonsurgically on postbreeding day 7. Ova were counted and classified as fertilized or unfertilized. Fertilized ova were scored as excellent, good, fair, poor, or degenerate. Unfertilized ova and poor and degenerate embryos were considered to be nontransferable ova and excellent, good, and fair embryos were considered to be transferable ova. There were no differences for mean number of fertilized, unfertilized, transferable, or nontransferable ova recovered from cows fed the 2 diets (P greater than 0.10). Mean percentage of fertilized ova recovered from cows was greater (P less than 0.05) in those fed diet 2, compared with diet 1. Mean percentage of transferable ova recovered from cows tended to be greater (P = 0.06) in those fed diet 2, compared with diet 1. More cows failed to yield transferable ova (P less than 0.05) when fed diet 1, compared with diet 2. Fertilization failure or early degeneration of embryos may occur in cows fed excess rumen degradable protein.  相似文献   

Cryosurgery for treatment of recurrent proliferative keratoconjunctivitis in five dogs     

C A Wheeler  G L Blanchard  H Davidson 《Journal of the American Veterinary Medical Association》1989,195(3):354-357

Cryosurgery was used for treatment of recurrent proliferative keratoconjunctivitis in 5 dogs that had been treated with combined medical and surgical procedures without success. Four dogs recovered completely after one application of cryosurgery. The fifth dog did not respond to cryosurgery until after oral administration of corticosteroids was stopped, indicating a possible immune-mediated mechanism of action of cryosurgery on proliferative keratoconjunctivitis.  相似文献   

Immunoglobulin A myeloma in a cat with pleural effusion and serum hyperviscosity   总被引：2，自引：0，他引：2  

E C Hawkins  B F Feldman  P C Blanchard 《Journal of the American Veterinary Medical Association》1986,188(8):876-878

Immunoglobulin A myeloma, serum hyperviscosity, and septic pleuritis were diagnosed in a cat with pleural and peritoneal effusions. Serum hyperviscosity was determined by use of a WBC pipette, and clinical manifestations included retinopathy and cardiac changes. The presence of Salmonella typhimurium in the pleural fluid may have resulted from increased susceptibility to infection. Postmortem examination revealed plasma cell infiltration of the pleura, mesenteric lymph nodes, and the serosa of the intestine, liver, and spleen. This case represents an unusual form of myeloma in the cat.  相似文献   

Venereal disease.     

T L Blanchard  R M Kenney  P J Timoney 《Veterinary Clinics of North America: Equine Practice》1992,8(1):191-203

Equine venereal infections of concern in the United States include EHV-3, T. equigenitalis, P. aeruginosa, and K. pneumoniae. Stallions may also harbor EAV in the genital tract and transmit the virus to mares during coitus. With the exception of EHV-3, the stallion generally remains asymptomatic while transmitting infections to mares during breeding. Methods for diagnosis, treatment, and control of these infections are discussed.  相似文献   

Effects of chronic GRF treatment on lambs having low or normal birth weight     

P. Pastoureau  J. Charrier  M.M. Blanchard  G. Boivin  J.P. Dulor  M. Theriez  B. Barenton 《Domestic animal endocrinology》1989,6(4):321-329

The effects of a long term treatment with human GRF(1–29)NH2 on plasma growth hormone (GH), somatomedin C (Sm-C), histomorphometric parameters of bone growth and body composition were investigated in normal and low birthweight male lambs. The animals were divided into two groups according to their birthweight: 24 normal birthweight (NBW) lambs weighing more than 4 kg and 22 low birthweight (LBW) lambs weighing less than 2.5 kg at birth. Half of the animals in each group received two daily subcutaneous injections (8 μg/kg body weight) of hGRF(1–29)NH2 (GRF) from birth to slaughter at 45 or 90 days of age. The other animals received the solvant only. At the beginning and at the end of the treatment, plasma GH and serum Sm-C concentrations were measured in all groups. After slaughter, a histomorphometric study was performed on undecalcified sections of metacarpal growth plates, and the remaining of the carcass was pulverized to study the chemical body composition.

GRF induced GH release in both GRF-treated groups. However, plasma GH reached higher (P<.001) concentrations and the GRF-induced GH peak lasted longer in LBW than in NBW lambs. At day 45, the GRF treatment increased (P<.05) serum Sm-C concentrations in LBW. Most of histomorphometric parameters reflecting the metacarpal growth in length, were not statistically modified under GRF treatment. However, the size of degenerative cells was smaller (P<.05) in LBW treated lambs as compared to controls. Consequently, the cell production in the growth plate was increased (P<.05) under GRF treatment. In both NBW and LBW groups at 45 days of treatment, GRF treatment reduced the amounts of lipids (P<.025) and energy (P<.05), while increased (P<.01) phosphorus deposition in the body. In contrast, there was no effect of GRF treatment on protein content.

We conclude from this experiment that the induction of GH secretion by a chronic treatment with GRF is able to modify some patterns of growth. However, most of the effects of GRF were observed in LBW lambs and after 45 days of treatment only. This suggests that treatment with GRF may serve to compensate for growth in growth-retarded animals. Further studies with different mode of GRF administration should indicate whether it is as much effective in normal animals.  相似文献   

Evaluation of equine corneal disease using spectral domain optical coherence tomography (SD‐OCT)     

Allison Blanchard  Erin M. Barr  Brian C. Gilger 《Veterinary ophthalmology》2019,22(6):791-798

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Individual tree diameter increment model for managed even-aged stands of ponderosa pine throughout the western United States using a multilevel linear mixed effects model   总被引：3，自引：0，他引：3  

Fabian C.C. Uzoh  William W. Oliver   《Forest Ecology and Management》2008,256(3):438

A diameter increment model is developed and evaluated for individual trees of ponderosa pine throughout the species range in the United States using a multilevel linear mixed model. Stochastic variability is broken down among period, locale, plot, tree and within-tree components. Covariates acting at tree and stand level, as breast height diameter, density, site index, and competition indices are included in the model as fixed effects in order to explain residual variability. The data set used in this study came from long-term permanent research plots in even-aged, pure stands both planted and of natural origin. The data base consists of six levels-of-growing stock studies supplemented by initial spacing and other permanent-plot thinning studies for a total of 310 plots, 34,263 trees and 153,854 observations. Regression analysis is the preferred technique used in growth and yield modeling in forestry. We choose the mixed effects models instead of the regression analysis approach because it allows for proper treatment of error terms in a repeated measures analysis framework. Regional growth and yield models exist for ponderosa pine. However, data collection and analysis procedures differ. As a result, comparisons of growth responses that may be due to geographic variation of the species are not possible. Our goal is to present a single distance-independent diameter increment model applicable throughout the geographic range of ponderosa pine in the United States and by using only data from long-term permanent plots on sites capable of the productivity estimated by Meyer [Meyer, W.H., 1938. Yield of Even-Aged Stands of Ponderosa Pine. US Department of Agriculture Technical Bulletin 630].  相似文献   

Bark phenolics of American beech (Fagus grandifolia) in relation to the beech bark disease1     

W. D. Ostrofsky  W. C. Shortle  R. O. Blanchard 《Forest Pathology》1984,14(1):52-59

The amount of total extractable phenols was determined for bark sections obtained from behind cankers naturally induced by Nectria coccinea var. faginata and from behind mechanically inflicted wounds on stems of American beech. Healthy bark from susceptible trees was found to contain a similar level of phenolics as bark from trees determined to be resistant to the beech bark disease. Six months after wounding, wound-altered bark from susceptible trees was found to be lower in phenols than woundaltered bark from resistant trees. Inoculation of wounds with N. coccinea var. faginata resulted in decreased phenolic levels in bark sections nearest the wound surface, and increased phenolic levels in sections nearest the vascular cambium, several mm distant. Phenolic levels in injured or infected bark appear to follow similar patterns as those resulting from injury or infection of xylem tissues.  相似文献