Genetic Engineering Approaches to Pig Production*

Modern biotechnology promises a number of new applications in animal breeding and production. Although conventional pig breeding has achieved a high level of efficiency and productivity numerous problems have been encountered with animal health and the loss of meat quality. Selection based on phenotypic performance data of individual animals does not take into account the importance of specific genes and their relevance within a complex regulatory system. In most cases it is therefore difficult to trace back the genetic origins of clinically important disorders. The application of genetic engineering techniques in pig production will facilitate diagnosis, improvement of productivity, and animal health by allowing direct genetic manipulation. Attention must be focussed on the physical and genetic analysis of the procine genome. The isolation and characterisation of genes, DNA-markers, polymorphic DNA-fragments, and their chromosomal assignment will be important prerequisites and tools for the elucidation of genetic disorders. Especially the detection of heterozygous carriers of recessive disorders and their elimination from the breeding stock will increase selection accuracy and decrease the generation intervals. But also the rapid and simple detection of infectious diseases, which is sometimes difficult if not impossible at present, will improve animal health and welfare. Although the production of transgenic animals either by DNA-microinjection into zygotes or the use of embryonal stem cells manipulated in vitro is less straightforward than DNA-based diagnosis it will play an important role in the direct manipulation of the porcine genome and genes. Breeding programmes including the use of transgenic livestock have already been developed. There is no doubt that genetic engineering has reached a degree of practical feasibility, allowing it to play an important role in pig breeding in particular and animal production in general.     

鼻咽癌来源LMP1转基因小鼠的制备

本试验利用显微注射技术,制备鼻咽癌来源LMP1基因（N-LMP1）的转基因小鼠。共获得15只首建鼠,经小鼠尾部组织DNA分析,PCR法证明其中两只小鼠有N-LMP1基因扩增带,Southern杂交显示PCR阳性小鼠有特异的杂交信号,整合率为13.3%,N-LMP1转基因小鼠的建立为研究N-LMP1转基因小鼠的建立为研究N-LMP1在鼻咽癌变过程中的作用机制奠定了基础。     

Resistance to the cabbage root fly, Delia radicum, within Brassica fruticulosa

Two transgenic Bt rice lines, KMD1 and KMD2, both containing a synthetic cry1Ab gene from Bt, were crossed with conventional rice varieties. The inheritance of resistance to SSB of KMD1 and KMD2was investigated through LSB and field examination of their progenies, e.g. F₁, BC₁ and F₂ populations. In LSBs, 100.0% of newly hatched SSB larvae died on the second day after feeding on leaf tissues of F₁ and GUS positive BC₁ plants, of which the area of leaf tissues consumed by SSB is also similar to that of transgenic parents. These results imply that the resistance of Bt rice to SSB is dominantly controlled and could be easily exploited in hybrid rice production. Field evaluation showed that segregation ratios for SSB resistance to susceptibility in BC₁ populations fit the ratio of 1:1, which was also confirmed by LSBs. However, in F₂ populations, the ratio was significantly smaller than 3:1 for resistant to susceptible plants in all 6 indica × japonica (KMD1 and KMD2) crosses, though it fitted 3:1 in all 4 japonica × japonica crosses. The results implied that the resistance of Bt rice to SSB was controlled by a dominant gene which was present in a homozygous condition in both KMD1 and KMD2, but the inheritance could be affected by other factors. Assays for Cry1Ab protein showed that, in most crosses, the content of Cry1Ab is significantly higher in leaves of GUS positive F₁, BC₁ and F₂ plants than that in transgenic Bt parent plants, which accounts for the high resistance observed in these plants to SSB. This revised version was published online in July 2006 with corrections to the Cover Date.     

Agrobacterium-mediated genetic transformation and production of semilooper resistant transgenic castor (Ricinus communis L.)

Summary Semilooper resistant transgenic castor plants were produced through Agrobacterium-mediated genetic transformation method. Two castor cultivars, Jyothi and VP1 were transformed using the super-binary vector pTOK233 carrying gus A and hpt genes. Putative transformants were regenerated following selection on the hygromycin containing medium. GUS positive primary transformants, when subjected to Southern analysis, revealed stable integration of gus A into their genomes. In the T₁ generation, a monogenic segregation ratio of 3 GUS positive: 1 GUS negative plants was observed. Furthermore, transformation experiments were carried out with the Agrobacterium pSB111 super-binary vector carrying a synthetic delta endotoxin gene cryIAb and the herbicide resistance gene bar both driven by cauliflower mosaic virus 35S promoter. Putative transformants were regenerated through selection on the phosphinothricin containing medium and Basta tolerant transformants were subjected to molecular analysis. PCR analysis revealed the presence of both bar and cryIAb genes in the Basta tolerant primary transformants. Southern analysis of PCR positive plants with cryIAb probe showed a 3 Kb band upon HindIII digestion and a > 6 Kb band with BamHI digestion, thus suggesting stable integration of cryIAb intact expression cassette and independent nature of the transformants. The primary transformants subjected to ELISA disclosed varied levels of Cry protein. These transgenics expressing cryIAb – when bioassayed against freshly hatched semilooper larvae – induced substantial (> 88%) insect mortality. Southern analysis of 2T₁ plants revealed the presence of cryIAb gene, indicating stable inheritance of the transgene into the next generation. In T₁, all the Southern-positive plants for cryIAb invariably exhibited tolerance to Basta, denoting co-segregation of both bar and cryIAb genes. Transgenics, expressing cryIAb exhibited ample resistance against the castor semilooper.     

The floral system of tomato

The tomato floral system is distinguished from that of Arabidopsis and Antirrhinum in several ways. The shoot is a sympodium, the first flower of the inflorescence is apical and no bracts are formed. We discuss the possible function of genes affecting growth habit and inflorescence development and analyze in detail the unique developmental alterations caused by inhibition or ectopic expression of tomato-specific MADS-box genes. Preliminary analysis of transgenic tomato plants expressing an alien homeotic gene and several different chimeric genes of the MADS-box family is also reported.     

Risk assessment of outcrossing of transgenic rapessed to related species:

Summary The risk for a gene dispersal is reported for reciprocal crosses between a transgenic rapeseed variety resistant to the herbicide phosphinotricin and five related species. The first stages after pollination were cytologically observed and fertilized ovaries were established in in vitro culture for the production of interspecific hybrids. A similar classification was observed for the index of pollination compatibility and embryo yield. From the 243 embryos produced, 109 plantlets were obtained in a greenhouse. All the interspecific combinations tested were able to produce hybrid plants. A higher number of hybrids was obtained when rapeseed was used as the female parent. The hybrids had the expected triploid structure except for two amphidiploid, B. napus × B. oleracea, and one amphidiploid, B. napus × S. arvensis, plants with 56 chromosomes. The triploid hybrids were sterile or partially fertile but two of the amphidiploid plants, B. napus × B. oleracea, were fully fertile. The cytoplasm source did not seem to affect the fertility of the hybrids.     

转Bt基因棉对棉铃虫抗性的时空动态

在室内研究了转Ｂｔ基因棉对棉铃虫抗性的时空动态及对棉铃虫幼虫取食行为的影响,结果表明,整个棉花生长期,棉花不同器官随着时间的变化其抗性有较大的差异,如７月以后,棉叶对棉铃虫幼虫的抗性明显下降,由６月下旬的１００％下降到８月初的６２．５％,然后抗性又逐渐回升,但仍为下降的趋势;从空间抗性来看,营养器官的抗性高于繁殖器官,接虫２４ｈ后,棉铃虫幼虫在转基因棉繁殖器官上分布数量较多;转基因棉对棉铃虫幼虫取食行为有较大的影响,和常规棉相比,在转基因棉上取食时间减少５７．６％,吐丝下垂、爬行和静息的时间分别延长３９６．１％、２２．４％和４．０％。