Requirements for the successful introduction and management of rotational irrigation

This paper attempts to identify the critical elements associated with the introduction and management of the practice of Rotational Irrigation in Taiwan, and thus to shed some light on the basic requirements for its successful adoption. While the emphasis is on this specific practice we believe it has implications for the transfer of other technologies in which physical, biological and managerial factors interact importantly.Seven irrigation associations in Taiwan were studied to identify the external conditions and system characteristics that are necessary for a successful change from continuous to rotational irrigation. Three external essentials are identified: (1) a water deficit approximating 25 percent of normal practice in the area; (2) political commitment to the change; (3) adequate financial resources for implementation and subsequent operation. Two system characteristics considered essential are: (1) physical facilities that provide for control and measurement to the level of farmer group responsibility; and (2) management patterns that provide a well-organized operating group and effective communication between the farmers and system personnel, resulting in a responsive plan of operation.Specific adaptations of the Taiwan practices to the local conditions will be necessary before effective transfer of this technology can take place elsewhere.     

Gas exchange responses of <Emphasis Type="Italic">Eucalyptus</Emphasis>, <Emphasis Type="Italic">C. africana</Emphasis> and <Emphasis Type="Italic">G. robusta</Emphasis> to varying soil moisture content in semi-arid (Thika) Kenya

A dramatic decline in forest cover in eastern Africa along with a growing population means that timber and poles for building and fuelwood are in short supply. To overcome this shortage, the region is increasingly turning to eucalyptus. But eucalyptus raises environmental concerns of its own. Fears that it will deplete water supply, affect wildlife and reduce associated crop yields have caused many countries in the region to discourage farmers from planting this exotic. This paper is part of a series of investigations on the growth and water use efficiency of faster growing eucalyptus hybrids, which was introduced from South Africa to Kenya. The hypothesis is that the new hybrids are more efficient in using water and more suitable for the semi-arid tropics than existing eucalyptus and two popular agroforestry species. Gas exchange characteristics of juvenile Eucalyptus grandis (W. Hill ex Maiden), two eucalyptus hybrids (E. grandis × Eucalyptus camaldulensis Dehnh.), Grevillea robusta (A. Cunn) and Cordia africana (Lam) was studied under field and pot conditions using an infrared gas analyzer was used to measure photosynthetic active radiation (PAR), net photosynthetic rate (A), stomatal conductance (g _s) and transpiration rate (E) at CO₂ concentrations of 360 μmol mol⁻¹ and ambient humidity and temperature. A, E and g _s varied between species, being highest in eucalyptus hybrid GC 15 (24.6 μmol m⁻² s⁻¹) compared to eucalyptus hybrid GC 584 (21.0 μmol m⁻² s⁻¹), E. grandis (19.2 μmol m⁻² s⁻¹), C. africana (17.7 μmol m⁻² s⁻¹) and G. robusta (11.1 μmol m⁻² s⁻¹). C. africana exhibited high E values (7.0 mmol m⁻² s⁻¹) at optimal soil moisture contents than G. robusta (3.9 mmol m⁻² s⁻¹) and eucalyptus (5.3 mmol m⁻² s⁻¹) in field experiment and G. robusta (3.2 mmol m⁻² s⁻¹) and eucalyptus (4.2 mmol m⁻² s⁻¹) in pot-grown trees. At very low soil moisture content, extremely small g _s values were recorded in GC 15 and E. grandis (8 mmol m⁻² s⁻¹) and G. robusta (14 mmol m⁻² s⁻¹) compared to GC 584 (46.9 mmol m⁻² s⁻¹) and C. africana (90.0 mmol m⁻² s⁻¹) indicating strong stomatal control by the species. Instantaneous water use efficiency ranged between 3 and 5 μmol mmol⁻¹ and generally decreased with decline in soil moisture in pot-grown trees but increased with declining soil moisture in field-grown trees.     

鱿鱼类资源量变化与海洋环境关系的研究进展

近几十年随着传统渔业资源量的下降,短生命周期的鱿鱼类产量出现持续增加,并已成为重要的渔获对象。由于鱿鱼类为短生命周期鱼类,对环境变化极为敏感,这一特点使得传统基于种群动力和生物学过程的资源量评估模型并不能很好地估算其资源量,为了了解环境因子和鱿鱼类资源量变化的关系,从研究方法和内容上对其研究现状进行了回顾,目前的研究已经能够在一定程度上解释环境因子对鱿鱼类资源量变化的影响机制,但是还不能完全利用环境变量来预测资源量的变化;本文还归纳了主要经济鱿鱼类栖息环境的特点,以及环境因子对其生活史各个阶段(孵化、仔稚鱼、成鱼和产卵)和资源补充量的影响,总结了目前研究遇到的问题和不足,并提出了今后研究重点应放在环境因子如何影响鱿鱼类生活史阶段中的孵化到仔稚鱼过程,从而能够提高对鱿鱼类补充量大小的估测精度,为其资源评估的进一步发展提供全面的理论基础。     

Comparison of diagnostics techniques in an outbreak of infectious laryngotracheitis from meat chickens

Various diagnostics techniques were compared for their ability to detect infectious laryngotracheitis (ILT) during an outbreak in chickens aged between 4 and 21 wk. Gross lesions ranged from excess mucus to accumulation of fibrinonecrotic exudate in the larynx and trachea. Syncytial cells with intranuclear inclusion bodies were found in sinus, conjunctiva, larynx, trachea, lung, and air sac. Virus isolation in chicken embryos was attempted in every case. Negative-stain electron microscopy detected herpesvirus in only 6% of the cases. Yet, isolation of ILT virus in the chorioallantoic membrane was presumed by histology in >20% of the samples and confirmed by fluorescent antibody (FA) in 35% of the embryos inoculated with conjunctivas or tracheas from affected birds. Overall, results from histology and FA tests were highly correlated. FA test has the advantage over histology of being diagnostically specific for ILT virus. Polymerase chain reaction was the most sensitive test and detected the viral DNA even in cases where histology and FA were negative. ILT virus DNA was quantified by real-time polymerase chain reaction (Re-Ti ILTV). Histologic and FA results from larynx and trachea were negative if the concentration of the viral DNA was < or =4 of log10. A viral DNA concentration higher than log10 4, as determined by Re-Ti ILTV, was required for clinical ILT to be manifested.     

Large-scale deployment of a rice 6 K SNP array for genetics and breeding applications

Background

Fixed arrays of single nucleotide polymorphism (SNP) markers have advantages over reduced representation sequencing in their ease of data analysis, consistently higher call rates, and rapid turnaround times. A 6 K SNP array represents a cost-benefit “sweet spot” for routine genetics and breeding applications in rice. Selection of informative SNPs across species and subpopulations during chip design is essential to obtain useful polymorphism rates for target germplasm groups. This paper summarizes results from large-scale deployment of an Illumina 6 K SNP array for rice.

Results

Design of the Illumina Infinium 6 K SNP chip for rice, referred to as the Cornell_6K_Array_Infinium_Rice (C6AIR), includes 4429 SNPs from re-sequencing data and 1571 SNP markers from previous BeadXpress 384-SNP sets, selected based on polymorphism rate and allele frequency within and between target germplasm groups. Of the 6000 attempted bead types, 5274 passed Illumina’s production quality control. The C6AIR was widely deployed at the International Rice Research Institute (IRRI) for genetic diversity analysis, QTL mapping, and tracking introgressions and was intensively used at Cornell University for QTL analysis and developing libraries of interspecific chromosome segment substitution lines (CSSLs) between O. sativa and diverse accessions of O. rufipogon or O. meridionalis. Collectively, the array was used to genotype over 40,000 rice samples. A set of 4606 SNP markers was used to provide high quality data for O. sativa germplasm, while a slightly expanded set of 4940 SNPs was used for O. sativa X O. rufipogon populations. Biparental polymorphism rates were generally between 1900 and 2500 well-distributed SNP markers for indica x japonica or interspecific populations and between 1300 and 1500 markers for crosses within indica, while polymorphism rates were lower for pairwise crosses within U.S. tropical japonica germplasm. Recently, a second-generation array containing ~7000 SNP markers, referred to as the C7AIR, was designed by removing poor-performing SNPs from the C6AIR and adding markers selected to increase the utility of the array for elite tropical japonica material.

Conclusions

The C6AIR has been successfully used to generate rapid and high-quality genotype data for diverse genetics and breeding applications in rice, and provides the basis for an optimized design in the C7AIR.

     

California National Animal Health Monitoring System for meat-turkey flocks, 1988-1989: diagnostic testing results.

Six hundred fourteen meat turkeys were submitted for necropsy from 24 California ranches as part of the National Animal Health Monitoring System (NAHMS). Enteritis was the most frequent pathologic diagnosis in birds 18 days old or younger and the second most frequent diagnosis in birds 19-70 days old. Hemorrhagic enteritis was the most frequent diagnosis in birds aged 19-70 days. Tibial dyschondroplasia, bronchopneumonia, and ascaridiasis were ranked one through three in frequency of diagnoses in birds over 70 days of age. Salmonella was isolated from 71% of flocks tested, and Mycoplasma meleagridis was isolated from 33% of tested flocks over 70 days of age. Antibodies to several disease agents were detected, including hemorrhagic enteritis (100% of flocks over 70 days old) and Newcastle disease (63% of flocks over 70 days old).     

Relationship of osteomyelitis and associated soft-tissue lesions with green liver discoloration in tom turkeys

Tom turkey carcasses with partial green discolored livers (n = 191) or normal livers (n = 198) were examined for osteomyelitis and/or associated soft-tissue lesions. Seventy-nine turkeys with green discolored livers had osteomyelitis and/or associated soft-tissue lesions (41.4%), including 53 with just osteomyelitis (27.7%), while 112 (59.6%) had no osteomyelitis and/or soft-tissue lesions. Only five turkeys (2.5%) with normal livers had osteomyelitis. Discolored livers were significantly heavier, but carcasses with discolored livers weighed significantly less than carcasses with normal livers. Bacteria were isolated from 54 of 61 osteomyelitis lesions (88.5%); most frequently staphylococci (50.8%) followed by Escherichia coli (14.8%), Streptococcus sp. (13.1%), and occasional other organisms. Most associated soft-tissue lesions and livers were sterile (74.7%). These finding indicate that although turkey carcasses with green discolored livers are more likely to have osteomyelitis and/or associated soft-tissue lesions than turkey carcasses with normal livers, there is also an approximately equal chance they will not have these lesions.     

利用GPS进行切沟侵蚀监测研究

切沟侵蚀在土壤侵蚀中占据重要位置,切沟侵蚀监测研究是切沟侵蚀研究的重要方面。目前进行切沟侵蚀监测研究主要利用摄影测量的方法,该方法存在一定的局限性。对利用GPS进行切沟侵蚀监测研究进行了探讨,对切沟在不同时间进行测量,获得多个时相的DEM,通过对比不同时相的DEM来获取该时间段的切沟侵蚀变化。最后以位于黑龙江省漫川漫岗黑土区的丰产电流域的一条切沟为研究实例,建立了2002,2003年10月两个时段分辨率为0.4 m的DEM,对比这两个时段的数据表明,该切沟沟头后退达13.78 m,侵蚀面积增大了711m~2,切沟的土壤侵蚀量增加了2377 m~3,展示了GPS在切沟侵蚀研究中精度高、速度快等优越性,可为切沟侵蚀监测研究提供参考。     

AIDS: an international perspective

The acquired immunodeficiency syndrome (AIDS) and infection with the human immunodeficiency virus type 1 (HIV-1) constitute a worldwide public health problem. Whereas in Europe and in most of the Americas transmission of HIV-1 has occurred predominantly among homosexual men and intravenous drug abusers, in Africa a distinct epidemiologic pattern has emerged that indicates that HIV-1 infection is mainly heterosexually acquired. Heterosexual transmission appears to be increasing in some parts of Latin America and the Caribbean, and possibly in the United States. In addition to HIV-1, at least one other human retrovirus, namely HIV-2, has been implicated as a cause of AIDS in Africa and Europe. Factors that influence heterosexual transmission of HIV-1 include genital ulcerations, early or late stages of HIV-1 infection in the index case, and possibly oral contraception and immune activation. The rate of perinatal transmission is enhanced when the mother's illness is more advanced. AIDS and HIV-1 infection may have a significant impact not only on public health, but also on the demography and socioeconomic conditions of some developing countries. Programs for the prevention and control of AIDS should be an immediate priority in all countries.