大兴安岭南段东南麓低山丘陵牧草种质资源初探     

德英  敖特根  赵来喜 《草业科学》2008,25(5):28-31

为了充分了解及有效保存内蒙古地区的牧草种质遗传资源,对大兴安岭南段东南麓低山丘陵各类天然草场资源的分布及组成进行了调查研究,根据采集植物标本的鉴定结果统计,该地区共有野生种子植物和蕨类植物774种,属88科329属,饲用植物占植物总数的82.17%.同时调查还发现,该区草地资源存在过度放牧、良种未得到充分保护等问题,并提出了一些针对性的建议,为进一步完善该地区牧草育种和良种繁殖体系及有效地保护和利用牧草种质资源提供参考.  相似文献   

Parasitic infections in dairy cattle around Hanoi, northern Vietnam     

Geurden T  Somers R  Thanh NT  Vien LV  Nga VT  Giang HH  Dorny P  Giao HK  Vercruysse J 《Veterinary parasitology》2008,153(3-4):384-388

In northern Vietnam, dairy cattle are mainly managed in small-scale farms, where animals are kept confined and feeding occurs by cut and carry methods. In the present study the occurrence of parasitic infections was examined in five provinces around Hanoi. A total of 201 farms were visited, and 334 stool and 239 blood samples were collected from calves younger than 3 months, animals between 3 and 24 months and adult cows. Furthermore, 254 milk samples were collected from lactating animals. Coproscopical examination indicated a high prevalence of nematode eggs (Cooperia spp., Haemonchus and Oesophagostomum spp.) in animals (n=176) between 3 and 24 months (66%) and in adult cows (n=90; 54%). In these age groups the prevalence of Fasciola was 28% and 39%, respectively, and for Paramphistomum the prevalence was 78% and 82%, respectively. Fifty percent of the calves younger than 3 months (n=68) were positive for Giardia, and none for Cryptosporidium. Most Giardia isolates were identified as the non-zoonotic G. duodenalis assemblage E on the beta-giardin gene. The blood samples were examined with commercially available Svanovir((R))Elisa's for the presence of Anaplasma marginale and Babesia bigemina specific antibodies, and a prevalence of 28% and 54% was found, respectively. In the milk samples Neospora caninum specific antibodies (Svanovir((R))Elisa) were detected in 30% of the lactating animals. The present study demonstrates that parasitic infections occur frequently in dairy cattle around Hanoi although animals are mainly kept confined, and indicates that further research on the economic impact of these infections is needed.  相似文献   

豪猪源福氏志贺菌的分离鉴定及喹诺酮类耐药基因检测     

张鹏飞  王印  德西措姆  杨泽晓  姚学萍  罗燕  廖倡宇 《中国预防兽医学报》2019,(2):204-208

为调查四川省某规模化豪猪养殖场中豪猪大面积腹泻死亡的原因,本研究采集病死豪猪的肠道内容物和肺脏等病料样品进行细菌的分离纯化,通过培养特性观察、革兰染色镜检、生化鉴定、16S rRNA基因的克隆测序进行鉴定,并对分离菌株进行致病性、耐药性分析,对其喹诺酮类耐药基因进行PCR检测并测序分析。结果显示,分离得到1株革兰阴性菌,该分离株符合福氏志贺菌的培养特性和生化特性,并且其16S rRNA基因序列与福氏志贺菌该基因序列的同源性为99%;对小鼠具有较强致病性;药敏试验结果显示分离株具有多重耐药性,仅对丁胺卡那敏感,对喹诺酮类、四环素类、头孢类、氨基糖苷类、青霉素类和氯霉素类药物均表现为耐药;分离株的DNA促旋酶Ⅱ和拓扑异构酶Ⅳ的喹诺酮耐药决定区均有突变,且携带有质粒介导的喹诺酮耐药基因qnr A和qnr S。本研究是国内首次关于豪猪源福氏志贺菌病的报道,为豪猪养殖中该细菌性疾病的诊断防治等相关研究提供参考。  相似文献   

Body temperature,activity patterns and hunting in free‐living cheetah: biologging reveals new insights     

Robyn S. HETEM  Duncan MITCHELL  Brenda A. DE WITT  Linda G. FICK  Shane K. MALONEY  Leith C. R. MEYER  Andrea FULLER 《Integrative zoology》2019,14(1):30-47

As one of the few felids that is predominantly diurnal, cheetahs (Acinonyx jubatus) can be exposed to high heat loads in their natural habitat. Little is known about long‐term patterns of body temperature and activity (including hunting) in cheetahs because long‐term concurrent measurements of body temperature and activity have never been reported for cheetahs, or, indeed, for any free‐living felid. We report here body temperature and locomotor activity measured with implanted data loggers over 7 months in 5 free‐living cheetahs in Namibia. Air temperature ranged from a maximum of 39 °C in summer to ?2 °C in winter. Cheetahs had higher (～0.4 °C) maximum 24‐h body temperatures, later acrophase (～1 h), with larger fluctuations in the range of the 24‐h body temperature rhythm (approximately 0.4 °C) during a hot‐dry period than during a cool‐dry period, but maintained homeothermy irrespective of the climatic conditions. As ambient temperatures increased, the cheetahs shifted from a diurnal to a crepuscular activity pattern, with reduced activity between 900 and 1500 hours and increased nocturnal activity. The timing of hunts followed the general pattern of activity; the cheetahs hunted when they were on the move. Cheetahs hunted if an opportunity presented itself; on occasion they hunted in the midday heat or in total darkness (new moon). Biologging revealed insights into cheetah biology that are not accessible by traditional observer‐based techniques.  相似文献   

New or Common Plant Diseases and Pests     

R AITKENHEAD  C. R. B. BAKER  G. W. D. DE  CHICKERA 《Plant pathology》1974,23(3):117-118

  相似文献   

The breakage of dormancy in Datura ferox seeds as an effect of water absorption     

LUCILA C. DE MIGUEL  ALBERTO SORIANO 《Weed Research》1974,14(4):265-270

Datura ferox seeds do not germinate when they are incubated intact and in darkness, even after 24 months of dry storage. If allowed to absorb water vapour for 3–4 weeks at 20°C, they lose dormancy, germinating even when incubated in darkness. The breakage of dormancy is directly related to the vapour pressure of the atmosphere where the seeds are stored, and good aeration is necessary for the process to occur. If seeds absorb liquid water, the toss of dormancy is much less than that of seeds stored in a saturated atmosphere. A similar effect is observed when seeds are buried in a soil at field capacity. The results indicate that a certain degree of imbibition, under good gas-exchange conditions, is important for breaking dormancy. As a hypothesis, it is proposed that most of the population remains dormant when not enough O₂ is available for (he imbibed seed. The low rate of O₂ entry could be due to poor diffusion through the water-saturated seed coat (seeds which absorb liquid water) or to a low O₂ level in the surrounding atmosphere (soil at field capacity). One of the possible roles of O₂ could be to oxidize the inhibitor(s) present in these seeds. La rupture de la dormance des semences de Datura ferox considérée comme un effet de l'absorplion de l'eau. Les semences de Datura ferox ne germent pas quand elles sont mises au germoir intactes et à l'obscurité, même aprés 24 mois de conservation au sec. Si elles peuvent absorber de la vapeur d'eau pendant 3 à 4 semaines à 20°C, elles perdent leur dormance et germent meme & à l'obscurité. La rupture de la dormance est en relation directe avec la pression de la vapeurd'eau de l'atmosphére dans laquelle les semences sont conservées; une bonne aération est nécessaire pour que le processus se déclanche. Si les semences absorbent de l'eau à l'état liquide, la rupture de dormance est beaucoup moindre que celle de semences conscrvées dans une atmosphére saturée. Un effet analogue est observé lorsque les semences sont ententes dans un sol ayant atteint sa capacity au champ. Les résultats indiquent qu'un certain degriS d'imbibition, sous de bonnes conditions d'changes gazeux. est important pour la rupture de la dormance. Comme hypothtése, il est proposé que la plus grande partie de la population reste dormante lorsqu'il n'y a pas assez d'oxygene disponible pour la semence imbibeée. Le faible taux d'absorption d'oxygéne pourrait étre du à sa fuible diffusion à travers l'enveloppe saturée d'eau de la semence (pour celles qui absorbent l'eau à I état liquide) ou à un bas niveau d'oxygene dans Tatmosphére environnante (cas d'un sol à la capacityé au champ). Un des rôles possibles de l'oxygéne pourrait être d'oxyder les inhibiteurs presents dans les semences. Das Brechen der Keimruhe in Samen von Datura ferox ah ein Effekt der Wasseraiifnahme Samen von Datura ferox keimen nicht, wenn sie bei Dunkelheit gehalten werden; auch nicht, wenn sie zuvor 24 Monate trocken lagerten. Wenn sie bei 20°C, 3 bis 4 Wochen tang Wasserdampf aufnehmen, verlieren sie die Keimhemmung und keimen sogar im Dunketn. Zwischcn dem Brechen der Keimruhe und dem Damptdruck der Luft in der sie gelagert werden, besteht eine direkte Beziehung. Fur diesen Vorgang ist eine gute BelCiflung Vorausselzung. Wenn die Samen flijssiges Wasser aufnehmen, ist der Verlust der Keimhemmung wesentlich geringer als wenn sie in einer gesättigten Atmosphäre gelagert werden. Eine ähnliche Wirkung wird beobachtet. wenn die Samen im Boden bei Feldkapazität gelagert werden. Die Ergebnisse zeigen, dass für das Brechen der Keimruhe ein bestimmtes Mass der Aufnahme bei ausreichendem Gasaustausch wichtig ist. Als cine Hypothese wird vorgeschlagen, dass die meisten der Population dormant bleiben, wenn für die mil Wasser vollgesaugten Samen nicht ausreichend O₂ verfügbar ist. Der geringe Zutritt an O₂ konnte auf die mässige Diffusion durch die wassergesättigte Samenschale (Samen die fliissiges Wasser aufnehmen), oder auf einen geringen O₂-Gehalt in der umgebenden Luft (Boden bei Feldkapazität) zurückzuführen sein. Eine der möglichen Bedeutungen die dem O₂ zukommen, könnte in der Oxidation des bzw. der Hemmstoffe der Samen liegen.  相似文献   

Capillary electrophoretic behaviour of humic substances from Sphagnum peats of various geographical origin: relation with the degree of decomposition     

G. BRAGATO  A. MORI  M. DE  NOBILI 《European Journal of Soil Science》1998,49(4):589-596

Humic substances (HS) extracted from 14 Sphagnum peats of various geographical origin were submitted tocapillary electrophoresis (CE) in free solution and in entangled polymer solutions (25 gl^-1 and 50 gl^?1) of polyethylene glycol (PEG). Electrophoretic runs were made in uncoated capillaries (75 μm internal diameter) using a tris-hydroxymethylaminomethane (TRIS)-phosphate buffer (pH 8.3) eventually containing PEG and applying a voltage of 10 kV. The HS extract of a Lithuanian peat was fractionated by ultrafiltration into five fractions with a nominal mean relative molecular mass (M) of 3000, 7500, 20 000, 75 000 and 200 000 Da. Without PEG, migration times were not correlated with the logarithm of M, but linear relations were obtained with 25gl^?1 and 50gl^?1 PEG solutions. Both solutions separated the different fractions by size; the best regression and the largest interval of linearity, M from 3000 to 200 000 Da, was obtained with the 25gl^?1 PEG solution. At 10kV and without PEG, migration times ranged from 6.5 to 8.1 min and did not differentiate the peats, whereas at 25gl^?1 PEG, migration times ranged from 3.3 to 6.5 min and, when plotted as a function of either the r value or the von Post index (H), which are used to evaluate the degree of decomposition of horticultural peats, they separated samples on the basis of their geographical origin and probable type of mire complex. At 25gl^?1 PEG, migration times also showed a well-defined linear decreasing trend with the increase of mean annual temperatures. These relations suggest the hypothesis that humification in mires goes along with an increase in the average size of humic molecules.  相似文献   

Effects of dissolved organic matter on the mobility of copper in a contaminated sandy soil   总被引：1，自引：0，他引：1  

E. J. M. TEMMINGHOFF  S. E. A. T. M. VAN DER  ZEE F. A. M. DE  HAAN 《European Journal of Soil Science》1998,49(4):617-628

Changes in land use can result in increased soil organic matter content, and decreases in Ca and pH which will affect the mobility of Cu in soil. We studied how the mobility and coagulation of dissolved organic matter and pH affected the mobility of Cu in contaminated sandy soil by batch and column experiments in the laboratory. The soil, with pH ranging from 3.8 to 5.7, had been polluted with Cu in the range 0.13–1.9 mmol kg^?1 more than a decade ago. Calcium and Cu bound by dissolved organic matter (purified humic acid) was determined in the pH range 4–8; Cu²⁺ concentration ranged from 10^?4 to 10^?12M and Ca²⁺ concentration from 10^?3 to 10^?6M. Binding of Cu by dissolved organic matter as affected by Ca and pH could be predicted well with the non-ideal competitive adsorption (NICA) model. Coagulation of dissolved organic matter was affected by the amount of trivalent (Al³⁺) and divalent (Ca²⁺ and Cu²⁺) cations in solution. There was little effect of pH on coagulation between pH 4 and 6. The concentration of the divalent cations, Ca²⁺ and Cu²⁺, at which coagulation of dissolved organic matter appeared could be explained by differences in the binding of Ca and Cu by dissolved organic matter. Binding of Cu by dissolved organic matter as well as by solid organic matter, both affected by Ca and pH, could be described well with the NICA model. We investigated the coagulation and mobility of dissolved organic matter in column experiments and found that they enhanced Cu mobility. Three processes, Cu desorption by soil, dissolved organic matter coagulation and Cu complexation by dissolved organic matter, act simultaneously in the soil columns. All three with counteracting effects on Cu mobility are influenced by Ca and pH and could be adequately represented by the multicomponent NICA model.  相似文献   

Analysis of Public Employment Impact Multipliers in Depressed Areas     

JACOB DE ROOY 《Growth and change》1980,11(2):32-38

  相似文献   

Growth and metabolic responses of tambaqui (Colossoma macropomum) fed different levels of protein and lipid     

L.C. DE ALMEIDA  I.M. AVILEZ  C.A. HONORATO  T.S.F. HORI  G. MORAES 《Aquaculture Nutrition》2011,17(2):e253-e262

Growth and metabolism were investigated in juvenile tambaqui (Colossoma macropomum) fed with isoenergetic diets in four treatments with protein (P) lipid (L) in g kg^?1: P350L49; P301L81; P253L113 and P205L145, respectively. The experiments were carried out in the laboratory facilities. Fish growth, the intermediary metabolites (total sugar, lactate, pyruvate, ammonia, protein, fatty acids, triacylglycerols, amino acids and glycogen), and the enzyme activities of lactate dehydrogenase, malate dehydrogenase, glutamate dehydrogenase, aspartate aminotransferase and alanine aminotransferase were assayed. Fish from treatments P350L49 and P301L81 depicted the best growth. Increase in glycolytic, glycogenolytic and lipolytic activities in liver was observed following dietary lipid increase. In fish fed with high lipid levels, the energetic demand was supplied by enhancement of muscular glycogenesis and lipolysis. The plasma metabolic profile reflected the blood function on metabolites delivery to tissues underlining biochemical adaptations because of changes in the feeding. In conclusion, the increase in dietary lipid plus protein decrease resulted in (i) reduction in fish growth, (ii) augment of liver glycolysis and glycogenolysis (iii) increase in muscular glycogenesis and (iv) predominance of lipolytic metabolism.  相似文献