Community‐based breeding programmes are a viable solution for Ethiopian small ruminant genetic improvement but require public and private investments

Ethiopia has a large and diverse population of small ruminants, which contribute substantially to the livelihood and income of the rural poor and the country at large. However, the sector faces a number of challenges. Productivity per animal and flock offtake are both very low. Reasons attributed for the apparent low productivity are as follows: absence of appropriate breeding programmes, lack of technical capacity, inadequate and poor‐quality feeds, diseases leading to high lamb mortality, and underdeveloped markets in terms of infrastructure and information. Historically, sheep and goats have received little policy or investment attention. Genetic improvement of small ruminants could contribute to bridging the productivity gap. In the past, the government of Ethiopia has placed much emphasis on importing exotic genetics and cross‐breeding with local stock as a strategy for genetic improvement. However, this has not led to a significant productivity improvement and the programmes have generally been unsustainable. Currently, there is a change in approach and a recognition of the need to focus genetic improvement efforts on the local genetic resources that are well adapted to the diverse agro‐ecologies and production environments in the country. Community‐based breeding programmes (CBBPs), which focus on indigenous stock and consider farmers’ needs, views, decisions and active participation, from inception through to implementation, have been identified as programmes of choice. The Ethiopian government and the private sector need to invest in strategic areas around CBBPs to make the programme work for the poor and be sustainable in low‐input systems.     

Rearrangement patterns of the canine TCRγ locus in a distinct group of T cell lymphomas

The T cell antigen receptor chains are assembled through a rearrangement process that combines variable (V), diversity (D) and joining (J) region genes. Recently, the entire canine T cell receptor γ (TRG) locus was described. It is arranged in 8 cassettes with up to 3 V genes, 2 J genes and 1 C gene each. However, no data is available beyond the level of sequence analysis. The objective of this study was to identify rearranged genes of the canine TRG locus through experimental analysis and to assess gene usage and patterns of rearrangement in a series of canine T cell lymphomas. Rearranged genes were identified through computational analysis of recombination signal sequences (RSSs), a gene's potential to generate a polyclonal smear, and through sequencing of clonal rearrangements in a series of T cell lymphomas. Out of a total of 32 Vγ and Jγ genes, 21 genes were found to rearrange, 8 genes were considered not rearranged and 3 genes were suspected to rearrange but their status could not be determined definitely. Rearrangements of the canine TRG locus were assessed in a group of canine T cell lymphomas as well as 3 neoplastic T cell lines. An average of 4.6 rearrangements per lymphoma was found suggesting that canine T cells routinely rearrange multiple cassettes per allele. The most commonly rearranged Vγ genes belonged to subgroups Vγ2, Vγ3, and Vγ7. Genes in cassettes 2 and 3 preferentially rearranged within their respective cassettes, while Vγ genes in cassette 7 rearranged to a Jγ gene in cassette 8. There was a strong preference for Vγ2 genes to rearrange to a 3' Jγ gene and for Vγ3 and Vγ7 genes to rearrange to a 5' Jγ gene. This rearrangement pattern coincided with the conservation of the spacer sequence between V and J gene subgroups rather than the topologic location of genes. These data show that highly divergent spacer sequences allow for equally efficient recombination and suggest that spacer sequences can mediate compatibility between V and J genes.     

Review of surrogacy program for endangered victorian brush-tailed rock wallaby (Petrogale penicillata) with special reference to animal husbandry and veterinary considerations.

A surrogacy program to increase the reproductive rate of the critically endangered Victorian brush-tailed rock wallaby (Petrogale penicillata), initially developed in semicaptive conditions, was established in close captivity at Adelaide Zoological Gardens in 1998. Pouch young were removed from their mothers on days 8-20 or 40-45 after parturition and placed onto the teat of a tammar wallaby (Macropus eugenii) or yellow-footed rock wallaby (Petrogale xanthopus xanthopus) surrogate mother. During the early years of the program, mortality of brush-tail pouch young was high (12/16, 75%), both before transfer while still on their mother (5/16) and after transfer to a surrogate mother (7/11). Changing pouch young transfer methodology and improving the health status of the surrogate animals during the later years of the program significantly reduced the mortality of brush-tail pouch young (8/29). Under the new methodology, no mortality of brush-tail pouch young was observed between birth and the time of transfer, (0/29), and after transfer, pouch young mortality rate was eight of 29 (28%). Factors implicated in the improved success of the program included 1) the early transfer (between days 8 and 20) of brush-tail pouch young from mother to surrogate mother, 2) review of the veterinary history and health of the animals selected to act as surrogate mothers, and 3) increased access to grazing pasture for foster mothers. The reproductive rate of the brush-tail females in the later years of the breeding program was sixfold above natural birthing rates. These and other factors important in establishing a breeding program of this nature are discussed.     

Imidazolinone herbicides: Synthesis and novel chemistry

The imidazolinone herbicides were prepared from reaction of an α- methylvaline fragment with an o-dicarboxylic acid. Early syntheses were completed through an imide amide intermediate, such as I or XV , followed by further cyclization to 2,5-diones III or XXI . Reaction of these diones with nucleophiles led to imidazolinones IV and V . The significant and interesting activity of these compounds led to new and versatile methods of synthesis, including resolution of the α-methylvaline fragments, development of a metallation-carboxylation route, a one-step picoline to imidazolinone route, and several pyridine and fused-ring pyridine syntheses.     

Permethrin treatments in canadian forests. Part 1: Impact on stream fish

The effects of permethrin on native and caged fish when aerially applied directly to forest streams at dosages between 8.8 and 70 g ha^?1 were studied between 1976 and 1981. None of the applications caused mortality of caged or native fish in streams. Trout and salmon diets were altered by the treatments due to effects on fish food organisms. The duration of the effects varied from several months to over a year with increasing dosage. Reductions in salmonid growth rates and reductions in fish densities in treated areas, presumably due to emigration, were documented following severe impacts on aquatic invertebrates in salmon nursery streams. Growth rates and population densities both recovered within four months after treatment.     

The transmission of geminiviruses by Bemisia tabaci

The cosmopolitan whitefly species, Bemisia tabaci (Gennadius) and Trialeurodes taporariorum (Westwood) have always been regarded as pests to a large range of worldwide crops. Both species are capable of transmitting plant viruses, with T. vaporariorum being the vector of only a few ‘clostero’-like viruses and B. tabaci the vector of viruses in several groups. The largest group of viruses transmitted by B. tabaci are the geminiviruses and B. tabaci is known to transmit around 60 members. Until recently, B. tabaci had been associated with only a limited range of host plants within any one region, although its total potential host range was large. Virus transmission was confined within the plant host range of each regional population of B. tabaci. The emergence of the polyphagous ‘B’ biotype of B. tabaci with its increased host range of more than 600 plant species, has resulted in geminiviruses infecting previously unaffected crops. As the ‘B’ biotype spreads further into Europe, European field and glasshouse crops have been shown to be susceptible to whitefly-transmitted viruses already endemic to other parts of the world. More than 20 colonies of B. tabaci, including both ‘B’ and non-‘B’ biotypes from disparate global locations have been compared for their ability to transmit more than 20 geminiviruses. All but two highly host-specific colonies were capable of transmitting most geminiviruses tested. However, some viruses were transmitted more efficiently than others. The virus coat protein or capsid is essential for vector recognition and transmission. By comparing transmissible viruses at the molecular level to viruses that are no longer whitefly-transmissible, the active epitope on the virus coat protein could be identified for designing future virus control strategies.     

Field validation of a decision support system for the control of pests and diseases in cereals in denmark

The decision in 1986, on an action plan to reduce pesticide use in Denmark by 50% led to increased research on the potential of reducing dosages. A decision support system (PC-Plant Protection), developed by The Danish Institute for Plant and Soil Science, implements this research. It combines a detailed use of threshold values to support decisions on treatment need, choice of pesticides and the appropriate dosage for actual problems in cereals. The pest and disease module within the system has been available commercially since 1993 and up to the end of April 1995, 2000 licences have been issued for its use at agricultural schools and by advisers and farmers. The recommendation model for pest and disease control has been validated in field trials since 1990. The validation has shown that the model is able to provide recommendations for the control of pests and diseases to a satisfactory level, without affecting farmers' gross margins. The model was able to adjust pesticide use to large yearly variations and the average amount of pesticides in the plots treated according to the model was well below that in the reference plots and in the commonly used strategies in Denmark.