Light-energy processing and freezing-tolerance traits in red spruce and black spruce: species and seed-source variation     

Major JE  Barsi DC  Mosseler A  Campbell M  Rajora OP 《Tree physiology》2003,23(10):685-694

Red spruce (Picea rubens Sarg.) and black spruce (Picea mariana (Mill.) B.S.P.) are genetically and morphologically similar but ecologically distinct species. We determined intraspecific seed-source and interspecific variation of red spruce and black spruce, from across the near-northern margins of their ranges, for several light-energy processing and freezing-tolerance adaptive traits. Before exposure to low temperature, red spruce had variable fluorescence (Fv) similar to black spruce, but higher photochemical efficiency (Fv/Fm), lower quantum yield, lower chlorophyll fluorescence (%), and higher thermal dissipation efficiency (qN), although the seed-source effect and the seed-source x species interaction were significant only for Fv/Fm. After low-temperature exposure (-40 degrees C), red spruce had significantly lower Fv/Fm, quantum yield and qN than black spruce, but higher chlorophyll fluorescence and relative fluorescence. Species, seed-source effect, and seed-source x species interaction were consistent with predictions based on genetic (e.g., geographic) origins. Multi-temperature exposures (5, -20 and -40 degrees C) often produced significant species and temperature effects, and species x temperature interactions as a result of species-specific responses to temperature exposures. The inherent physiological species-specific adaptations of red spruce and black spruce were largely consistent with a shade-tolerant, late-successional species and an early successional species, respectively. Species differences in physiological adaptations conform to a biological trade-off, probably as a result of natural selection pressure in response to light availability and prevailing temperature gradients.  相似文献   

Soil carbon distribution and quality in a montane rangeland-forest mosaic in northern Utah     

Helga Van Miegroet  Janis L. Boettinger  Michelle A. Baker  Julia Nielsen  Dave Evans  Alex Stum 《Forest Ecology and Management》2005,220(1-3):284-299

Relatively little is known about soil organic carbon (SOC) dynamics in montane ecosystems of the semi-arid western U.S. or the stability of current SOC pools under future climate change scenarios. We measured the distribution and quality of SOC in a mosaic of rangeland-forest vegetation types that occurs under similar climatic conditions on non-calcareous soils at Utah State University's T.W. Daniel Experimental Forest in northern Utah: the forest types were aspen [Populus tremuloides] and conifer (mixture of fir [Abies lasiocarpa] and spruce [Picea engelmannii]); the rangeland types were sagebrush steppe [Artemisia tridentata], grass-forb meadow, and a meadow-conifer ecotone. Total SOC was calculated from OC concentrations, estimates of bulk density by texture and rock-free soil volume in five pedons. The SOC quality was expressed in terms of leaching potential and decomposability. Amount and aromaticity of water-soluble organic carbon (DOC) was determined by water extraction and specific ultra violet absorbance at 254 nm (SUVA) of leached DOC. Decomposability of SOC and DOC was derived from laboratory incubation of soil samples and water extracts, respectively.

Although there was little difference in total SOC between soils sampled under different vegetation types, vertical distribution, and quality of SOC appeared to be influenced by vegetation. Forest soils had a distinct O horizon and higher SOC concentration in near-surface mineral horizons that declined sharply with depth. Rangeland soils lacked O horizons and SOC concentration declined more gradually. Quality of SOC under rangelands was more uniform with depth and SOC was less soluble and less decomposable (i.e., more stable) than under forests. However, DOC in grass-forb meadow soils was less aromatic and more bioavailable, likely promoting C retention through cycling. The SOC in forest soils was notably more leachable and decomposable, especially near the soil surface, with stability increasing with soil depth. Across the entire dataset, there was a weak inverse relationship between the decomposability and the aromaticity of DOC. Our data indicate that despite similar SOC pools, vegetation type may affect SOC retention capacity under future climate projections by influencing potential SOC losses via leaching and decomposition.  相似文献   

Acute tracheal compression in a large breed dog due to a dorsal tracheal membrane abscess          下载免费PDF全文

Alex M. Lynch BVSc  DACVECC  Therese E. O'Toole DVM  DACVIM  DACVECC  John E. Rush DVM  DACVIM  DACVECC  Danielle Rondeau DVM  DACVIM  Kelly O'Neill DVM  DACVIM  Raymond K. Kudej DVM  PhD  DACVS 《Journal of Veterinary Emergency and Critical Care》2015,25(6):795-800

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Global parasite and Rattus rodent invasions: The consequences for rodent‐borne diseases          下载免费PDF全文

Serge MORAND  Frédéric BORDES  Hsuan‐Wien CHEN  Julien CLAUDE  Jean‐François COSSON  Maxime GALAN  Gábor Á CZIRJÁK  Alex D GREENWOOD  Alice LATINNE  Johan MICHAUX  Alexis RIBAS 《Integrative zoology》2015,10(5):409-423

We summarize the current knowledge on parasitism‐related invasion processes of the globally invasive Rattus lineages, originating from Asia, and how these invasions have impacted the local epidemiology of rodent‐borne diseases. Parasites play an important role in the invasion processes and successes of their hosts through multiple biological mechanisms such as “parasite release,” “immunocompetence advantage,” “biotic resistance” and “novel weapon.” Parasites may also greatly increase the impact of invasions by spillover of parasites and other pathogens, introduced with invasive hosts, into new hosts, potentially leading to novel emerging diseases. Another potential impact is the ability of the invader to amplify local parasites by spillback. In both cases, local fauna and humans may be exposed to new health risks, which may decrease biodiversity and potentially cause increases in human morbidity and mortality. Here we review the current knowledge on these processes and propose some research priorities.  相似文献   

Effect of a Bowman-Birk proteinase inhibitor from Phaseolus coccineus on Hypothenemus hampei gut proteinases in vitro     

de Azevedo Pereira R  Valencia-Jiménez A  Magalhães CP  Prates MV  Melo JA  de Lima LM  de Sales MP  Tempel Nakasu EY  da Silva MC  Grossi-de-Sá MF 《Journal of agricultural and food chemistry》2007,55(26):10714-10719

The coffee berry borer, Hypothenemus hampei (Ferrari), is an important devastating coffee pest worldwide. Both trypsin and chymotrypsin enzyme activities from H. hampei larval midgut can be inactivated by proteinaceous enzyme-inhibitors. A serine proteinase inhibitor belonging to the Bowman-Birk class was purified from a wild accession of Phaseolus coccineus L. seeds. The inhibitor (PcBBI1) is a cysteine-rich protein that is heat-stable at alkaline pH. MALDI-TOF/MS analysis showed that PcBBI1 occurs in seeds as a monomer (8689 Da) or dimer (17,378 Da). Using in vitro inhibition assays, it was found that PcBBI1 has a high inhibitory activity against H. hampei trypsin-like enzymes, bovine pancreatic chymotrypsin, and trypsin. According to this, PcBBI1 could be a promising tool to make genetically modified coffee with resistance to coffee berry borer.  相似文献   

Hormonal changes during meiotic maturation and ovulation in the brook trout (Salvelinus fontinalis)     

Frederick W. Goetz  Alexis Y. Fostier  Bernard Breton  Bernard Jalabert 《Fish physiology and biochemistry》1987,3(4):203-211

The plasma levels of estradiol-17 (E2), 17, 20-dihydroxy-4-pregnen-3-one (17,20-P) and gonadotropin (GTH) were measured in brook trout (Salvelinus fontinalis) during the period from the end of vitellogenesis to postovulation. Blood samples were taken according to specific stages of maturation, including germinal vesicle breakdown (GVBD) and ovulation. E2 levels were quite high (45 ng/ml) at the end of vitellogenesis (and prior to GVBD) and dropped precipitously by GVBD (2 ng/ml). They remained low through ovulation and postovulation. 17,20-P levels were low prior to GVBD (0.7 ng/ml) and increased dramatically at GVBD (148 ng/ml). The levels of 17,20-P remained high at ovulation (142 ng/ml) and then dropped significantly within 24 h to approximately half of the ovulatory values. They decreased even further by 7 days postovulation. GTH levels rose gradually through GVBD and ovulation from a postvitellogenic level of approximately 3 ng/ml to a 7 day postovulatory value of approximately 10 ng/ml. The overall results; 1) decrease in estradiol prior to GVBD, 2) increase in 17,20-P at GVBD and 3) gradual GTH rise through GVBD and ovulation, are similar to those reported for other salmonids.  相似文献   

Transient Fanconi syndrome in Quarter horses     

Cameon M. Ohmes  Elizabeth G. Davis  Laurie A. Beard  Karie A. Vander Werf  Alex W. Bianco  Urs Giger 《The Canadian veterinary journal. La revue veterinaire canadienne》2014,55(2):147-151

Two Quarter horses with weight loss had glucosuria, euglycemia, and a mild metabolic acidosis suggesting a proximal renal tubular defect. Further testing revealed transient generalized aminoaciduria, lactic aciduria, and glucosuria, indicating Fanconi syndrome. Both horses recovered with supportive therapy. This is the first report of acquired Fanconi syndrome in horses.  相似文献   

Short-wave solar radiation level willingly tolerated by lactating Holstein cows in an equatorial semi-arid environment     

Steffan Edward Octávio Oliveira  Cíntia Carol de Melo Costa  João Batista Freire de Souza Jr  João Paulo Araújo Fernandes de Queiroz  Alex Sandro Campos Maia  Leonardo Lelis de Macedo Costa 《Tropical animal health and production》2014,46(8):1413-1417

The amount of short-wave solar radiation willingly tolerated by lactating Holstein cows on pasture was determined in an equatorial semi-arid environment. The study was carried out on a dairy farm located in Limoeiro do Norte, CE, northeastern Brazil. The observed behaviours were as follows: grazing, under the sun, under the shade, standing, lying, ruminating, idling and wallowing in the water. The behaviours were recorded using instantaneous scan sampling at regular intervals of 15 min from 0600 to 1800 hours over 5 days. On all sampling days, the meteorological variables, including local short-wave solar radiation (R _S-W, W m^?2), were recorded. The R _S-W data were divided into five levels. The sun exposure was more frequent under low (100 %) and moderately low (97 %) levels, when R _S-W remained below 500 W m^?2. The grazing was more intense under low (100 %) and moderately low (93 %) levels. Above 500 W m^?2, the grazing time significantly decreased (11 %). The cows avoided grazing under high (0 %) and very high (0 %) levels, when R _S-W exceeded 700 W m^?2. The ruminating behaviour was more frequent under high (33 %) and very high (37 %) levels, in which the highest averages of R _S-W were recorded (815 and 958 W m^?2, respectively). The standing posture was more frequent under low (100 %) and moderately low (97 %) levels. Therefore, the critical R _S-W level that motivates cows to stop grazing and seek shade was in the interval between 500 and 700 W m^?2.  相似文献   

Dietary nano-chromium tripicolinate increases feed intake and decreases plasma cortisol in finisher gilts during summer   总被引：1，自引：1，他引：0  

Alex Tsungyu Hung  Brian Joseph Leury  Matthew Allen Sabin  Cherie Louise Collins  Frank Rowland Dunshea 《Tropical animal health and production》2014,46(8):1483-1489

Chromium (Cr) is an essential mineral element and has been used in pig diets to improve growth performance, insulin sensitivity, immune response and carcase traits and to reduce heat or other stress responses. The aims of thiss study were to determine the impact of nano-sized chromium tripicolinate (nCrPic) on growth performance, feed efficiency and carcase characteristics of finisher gilts during the summer period. A total of 60 finisher Large White x Landrace gilts were stratified on initial weight and then within strata randomly allocated into two treatment groups in three replicates during mid-summer for 28 days. All pigs were housed in individual pens and had ad libitum access to feed and water. Pigs were fed either a control finisher diet (wheat-based diet containing 13.8 MJ digestible energy (DE) per kilogram and 0.56 g available lysine/MJ DE) or a control diet containing 400 ppb Cr as nCrPic. Dietary nCrPic supplementation increased feed intake by 6 % over the entire study (P?=?0.05). In particular, dietary nCrPic increased average daily feed intake (ADFI) by 8 % (P?=?0.02) during the final 2 weeks of the study. Moreover, dietary nCrPic tended to improve average daily feed (ADFI) over the entire study (P?=?0.09). However, there were no significant effects of nCrPic on feed conversion ratio (FCR), final weight, hot standard carcase weight (HCWT), P2 depth or dressing percentage. Plasma cortisol was decreased by 25 % (P?=?0.06) by dietary nCrPic supplementation. However, there were no effects of nCrPic on plasma glucose, insulin and nonesterified fatty acids (NEFA), might because of the higher feed intake. In conclusion, this study demonstrates that dietary nCrPic supplementation at 400 ppb can increase feed intake in finisher gilts during mid-summer, suggesting that nCrPic can ameliorate some of the negative effects of heat stress in pigs, possibly via decreased of circulating cortisol.  相似文献   

Changes in fetal mannose and other carbohydrates induced by a maternal insulin infusion in pregnant sheep     

Laura D Brown  Stephanie R Thorn  Alex Cheung  Jinny R Lavezzi  Frederick C Battaglia  Paul J Rozance 《畜牧与生物技术杂志(英文版)》2014,5(1):28

Background

The importance of non-glucose carbohydrates, especially mannose and inositol, for normal development is increasingly recognized. Whether pregnancies complicated by abnormal glucose transfer to the fetus also affect the regulation of non-glucose carbohydrates is unknown. In pregnant sheep, maternal insulin infusions were used to reduce glucose supply to the fetus for both short (2-wk) and long (8-wk) durations to test the hypothesis that a maternal insulin infusion would suppress fetal mannose and inositol concentrations. We also used direct fetal insulin infusions (1-wk hyperinsulinemic-isoglycemic clamp) to determine the relative importance of fetal glucose and insulin for regulating non-glucose carbohydrates.

Results

A maternal insulin infusion resulted in lower maternal (50%, P < 0.01) and fetal (35-45%, P < 0.01) mannose concentrations, which were highly correlated (r² = 0.69, P < 0.01). A fetal insulin infusion resulted in a 50% reduction of fetal mannose (P < 0.05). Neither maternal nor fetal plasma inositol changed with exogenous insulin infusions. Additionally, maternal insulin infusion resulted in lower fetal sorbitol and fructose (P < 0.01).

Conclusions

Chronically decreased glucose supply to the fetus as well as fetal hyperinsulinemia both reduce fetal non-glucose carbohydrates. Given the role of these carbohydrates in protein glycosylation and lipid production, more research on their metabolism in pregnancies complicated by abnormal glucose metabolism is clearly warranted.  相似文献