Seed dispersal and its implications for silviculture of African mahogany (Entandrophragma spp.) in undisturbed forest in the Central African Republic     

Vincent Medjibe  Jefferson S. Hall   《Forest Ecology and Management》2002,170(1-3):249-257

The study of seed dispersal has received considerable attention in tropical ecology with emphasis placed on its role in the maintenance of species diversity. Since seeds of numerous high-value tropical timber trees are nominally or actively wind dispersed, the subject is also of interest to tropical foresters. In central Africa, up to 70% of harvested timber trees are wind dispersed, including African mahoganies of the genus Entandrophragma. The dual goals of managing many remote areas in central Africa for both biodiversity and timber production values has led to the consideration of low impact logging techniques. In the Central African Republic, increasing light downwind of Entandrophragma has been proposed as a way of increasing regeneration and recruitment of these trees. Mean wind direction at the time of dehiscence of Entandrophragma angolense and Entandrophragma cylindricum was compared with compass orientation of seed shadows for five individuals in mature, undisturbed forest. Mean wind direction was found to be toward the northeast for morning, afternoon, and daily winds and was significantly different from the orientation of seed shadows for all trees. Mean branch direction did not vary significantly from a random pattern, but matched the direction of the seed shadow better than wind direction did. It is concluded that harvesting interventions aimed at increasing light downwind of Entandrophragma will not necessarily benefit seedlings of the species at the study site and further silvicultural research is needed to determine appropriate management interventions, particularly in remote areas of Africa where conservation values are important.  相似文献   

Selection in early generations and the occurrence of heterosis for the character root distribution     

Diego Toaldo  Pedro Patric Pinho de Morais  Jaqueline Battilana  Jefferson Luís Meirelles Coimbra  Altamir Frederico Guidolin 《Euphytica》2013,190(3):335-344

Crops of bean are sensible to climate changes, especially water stress. One way to minimize this instability is through genetic breeding of root system character. Thus, the objective of this study was to identify genotypes with superior root system in the first segregating generation at three depths in the soil profile and also verify the occurrence of heterosis for the root system character. Evaluations were performed using the method of Bohm (Methods studying root systems. Springer, Berlin 1979) at three different depths (0–10, 10–20 and 20–30 cm), in the experimental area of the Institute of Molecular Genetics and Breeding, at the State University of Santa Catarina UDESC Lages-SC. Twelve segregating populations and four parents (BAF 09, BAF 07, BAF 50 and IPR Uirapuru) were assessed by comparison. The favorable genotypes to the progress of generations are: two, seven and three for depths up to 20 cm and three for depths up to 30 cm. The cross between the parents BAF 07 (black group) and BAF 50 (carioca group) presented wide genetic divergence, providing significant increase in the root system revealed by the analysis of their progenies. The selection of superior genotypes in the layer of 20–30 cm was limited because most genotypes have similar and poorly distribution. Due to the strong effect of the dominance component, heterosis occurred for root distribution in early generation. This fact may interfere in the selection of autogamous species of bean related to this genetic character.  相似文献   

Expression and Characterization of Constitutive Heat Shock Protein 70.1 (HSPA‐1A) Gene in In Vitro Produced and In Vivo‐Derived Buffalo (Bubalus bubalis) Embryos     

GT Sharma  A Nath  S Prasad  S Singhal  N Singh  NE Gade  PK Dubey  G Saikumar 《Reproduction in domestic animals》2012,47(6):975-983

Cells are blessed with a group of stress protector molecules known as heat shock proteins (HSPs), amongst them HSP70, encoded by HSPA‐1A gene, is most abundant and highly conserved protein. Variety of stresses hampers the developmental competence of embryos under in vivo and in vitro conditions. Present work was designed to study the quantitative expression of HSPA‐1A mRNA in immature oocytes (IMO), matured oocytes (MO), in vitro produced (IVP) and in vivo‐derived (IVD) buffalo embryos to assess the level of stress to which embryos are exposed under in vivo and in vitro culture conditions. Further, HSPA‐1A gene sequence was analysed to determine its homology with other mammalian sequences. The mRNA expression analysis was carried out on 72 oocytes (40 IMO; 32 MO), 76 IVP and 55 IVD buffalo embryos. Expression of HSPA‐1A was found in oocytes and throughout the developmental stages of embryos examined irrespective of the embryo source; however, higher (p < 0.05) expression was observed in 8–16 cell, morula and blastocyst stages of IVP embryos as compared to IVD embryos. Phylogenetic analysis of bubaline HSPA‐1A revealed that it shares 91–98% identity with other mammalian sequences. It can be concluded that higher level of HSPA‐1A mRNA in IVP embryos in comparison with in vivo‐derived embryos is an indicator of cellular stress in IVP system. This study suggests need for further optimization of in vitro culture system in which HSPA‐1A gene could be used as a stress biomarker during pre‐implantation development.  相似文献   

Development of microsatellite markers and evaluation of genetic diversity of the Amazonian ornamental fish Pterophyllum scalare     

Pandolfi  Victor César Freitas  Yamachita  Andrei Lincoln  de Souza  Felipe Pinheiro  de Godoy  Sara Mataroli  de Lima  Ed Christian Suzuki  Feliciano  Daniele Cassiano  de Pádua Pereira  Ulisses  Povh  Jayme Aparecido  Ayres  Denise Rocha  Bignardi  Annaiza Braga  Penafort  Jefferson Murici  de Fátima Ruas  Claudete  Lopera-Barrero  Nelson Mauricio 《Aquaculture International》2021,29(6):2435-2449

The objective of the present work was to develop species-specific microsatellite markers for P. scalare and to analyze the diversity and genetic structure of a wild population, from the Amazon River, and three commercial stocks (common, marble, and clown morphological variants), from farmers in Vieras-Minas Gerais. Through microsatellite-enriched genetic libraries, 11 microsatellite markers with adequate amplification patterns were characterized. Population genetic analysis identified eight polymorphic loci that generated 66 alleles ranging from two alleles (PSCA1B3) to nine (PSCA2H1). The polymorphic information content ranged from 0.031 to 0.827. High genetic differentiation was observed between the wild population and the stocks, and moderate differentiation between the three stocks. Deviation in the Hardy-Weinberg equilibrium was observed in one locus in the wild population, in five loci in the common morphological variant, in two in the marble, and in two in the clown morphological variant. Bayesian analysis of genetic structure revealed the existence of two clusters, one represented by the natural population and the other by the stocks. The developed microsatellite markers serve as a tool for the analysis of diversity and genetic structure and conservation studies of P. scalare.

  相似文献   

Stratification,Blinding and Placebo Effect in a Randomized,Double Blind Placebo-controlled Clinical Trial of Gold Bead Implantation in Dogs with Hip Dysplasia     

GT J?ger  S Larsen  L Moe 《Acta veterinaria Scandinavica》2005,46(2):57-68

The purpose of this study was to investigate the need for and choice of stratification factors, and the effects of blinding and placebo in a clinical experiment. Eighty dogs with canine hip dysplasia (CHD) were included in a randomized, placebo-controlled and double blind clinical trial with stratified parallel group design, in which body weight and degree of CHD were used as stratification factors. Thirty-eight dogs were allocated to gold bead implantation and 42 to placebo. After six months, 33 of the 42 placebo-treated dogs received gold bead implantation in an open study lasting a further 18 months. The main outcome variable in the study was change in pain signs of CHD as assessed by the owner. No significant difference in the main outcome variable, regardless of the treatment given, could be detected in the two chosen stratification factors. The only factor to influence the main outcome variable significantly was age. The blinding procedure used in the study, in which 60% of the owners correctly guessed the treatment given, was found sufficient. Of those who guessed the treatment erroneously, 88% believed the treatment given was gold bead implantation. The treatment efficacy after six months in the blinded treatment group was found to be significantly larger compared to the efficacy obtained in the open study. A significant placebo effect was therefore detected. Conclusion and Clinical Relevance: The age of the dogs influenced the outcome of the CHD treatment, and is recommended as a stratification factor. A significant placebo effect has to be expected and an optimal blinding procedure is necessary in similar clinical studies.  相似文献   

中西医结合防治鸭传染性浆膜炎   总被引：1，自引：0，他引：1  

孟冬霞  武果桃  赵娟  孙建钢  任杰 《中国兽药杂志》2006,40(8):59-60

鸭传染性浆膜炎即鸭疫里默氏杆菌病，是严重危害鸭生产的主要传染病之一。根据病鸭的流行病学、临床症状、剖检症状及实验室诊断，确诊为鸭传染性浆膜炎。采取中西医综合防治措施，取得较好疗效。  相似文献   

Preventive health care of Pony Club horses in rural New South Wales,Australia          下载免费PDF全文

P Buckley  D Buckley  GT Coleman  JM Morton 《Australian veterinary journal》2016,94(8):265-270

  相似文献   

The Association of Shelter Veterinarians veterinary medical care guidelines for spay-neuter programs     

Looney AL  Bohling MW  Bushby PA  Howe LM  Griffin B  Levy JK  Eddlestone SM  Weedon JR  Appel LD  Rigdon-Brestle YK  Ferguson NJ  Sweeney DJ  Tyson KA  Voors AH  White SC  Wilford CL  Farrell KA  Jefferson EP  Moyer MR  Newbury SP  Saxton MA  Scarlett JM;Association of Shelter Veterinarians' Spay  Neuter Task Force 《Journal of the American Veterinary Medical Association》2008,233(1):74-86

As efforts to reduce the overpopulation and euthanasia of unwanted and unowned dogs and cats have increased, greater attention has been focused on spay-neuter programs throughout the United States. Because of the wide range of geographic and demographic needs, a wide variety of programs have been developed to increase delivery of spay-neuter services to targeted populations of animals, including stationary and mobile clinics, MASH-style operations, shelter services, feral cat programs, and services provided through private practitioners. In an effort to ensure a consistent level of care, the Association of Shelter Veterinarians convened a task force of veterinarians to develop veterinary medical care guidelines for spay-neuter programs. The guidelines consist of recommendations for preoperative care (eg, patient transport and housing, patient selection, client communication, record keeping, and medical considerations), anesthetic management (eg, equipment, monitoring, perioperative considerations, anesthetic protocols, and emergency preparedness), surgical care (eg, operating-area environment; surgical-pack preparation; patient preparation; surgeon preparation; surgical procedures for pediatric, juvenile, and adult patients; and identification of neutered animals), and postoperative care (eg, analgesia, recovery, and release). These guidelines are based on current principles of anesthesiology, critical care medicine, microbiology, and surgical practice, as determined from published evidence and expert opinion. They represent acceptable practices that are attainable in spay-neuter programs.  相似文献   

Seed and seedling survival of African mahogany (Entandrophragma spp.) in the Central African Republic: Implications for forest management     

Jefferson S. Hall 《Forest Ecology and Management》2008

African mahoganies of the genus Entandrophragma are among the most valuable and important timber species harvested in Central Africa, representing more than 70% of total export volume from many areas. In spite of the importance of these species, relatively little is known about their regeneration ecology and little effort has gone into understanding the reasons for the consistently reported regeneration failures after logging. I assessed seed survival to germination (Entandrophragma angolense) and seedling survivorship (E. cylindricum) in three different forest types – monodominant Gilbertiodendron, mixed species, and fallow forest – under three different treatments – control, small mesh chicken wire, and large mesh chicken wire – to evaluate the relative importance of different causes of mortality. All seeds were eaten in controls and in both exclosure treatments within Gilbertiodendron forest in a matter of days. Seed survivorship to germination within exclosures in mixed species and fallow forest increased by approximately 10 and 25%, respectively, compared to Gilbertiodendron forest. Six-month seedling survivorship in controls was 37, 12, and 9% in Gilbertiodendron, mixed species and fallow forest, respectively. Seedling mortality was due to different causes in each forest type. In Gilbertiodendron forest controls, an equivalent percentage of seedlings died due to fungal and insect attack (27 and 28%, respectively), while in mixed species forest controls 28 and 55% of seedlings died of these causes, respectively. In fallow forest controls, 48% of seedlings died from predation and/or uprooting by small mammals, all in the first few weeks post-sowing; insect attack (26%) and drought (13%) were other important causes of seedling deaths. Protecting seedlings with exclosures had a dramatic effect on seedling survivorship within the fallow forest, increasing to over 50%.  相似文献   

Updated morphology,histopathology and molecular phylogeny of Myxobolus hearti,cardiac myxosporea in gibel carp,Carassius gibelio (Bloch)     

LT Ye  WX Li  WW Wang  SG Wu  GT Wang 《Journal of fish diseases》2014,37(1):11-20

  相似文献