Jesse M. Jaynes

Transfer and expression of an artificial storage protein (ASP1) gene in cassava (Manihot esculenta Crantz).

In order to increase the nutritional quality of cassava storage roots, which contain up to 85% starch of their dry weight, but are deficient in protein, a synthetic ASP1 gene encoding a storage protein rich in essential amino acids (80%) was introduced into embryogenic suspensions of cassava via Agrobacterium-mediated gene transfer. Transgenic plants were regenerated from suspension lines derived from hygromycin-resistant friable embryogenic callus lines. Molecular analysis showed the stable integration of asp1 in cassava genome and its expression at RNA level in transformed suspension lines. PCR and Southern analyses proved the transgenic nature of the regenerated plant lines. The expression of asp1 at RNA level was demonstrated by RT-PCR. The ASP1 tetramer could be detected in leaves as well as in primary roots of cultured transgenic plants by western blots. These results indicate that the nutritional improvement of cassava storage roots may be achieved by constitutive expression of asp1 in transgenic plants.

Interleukin 2 promoter/enhancer controlled expression of a synthetic cecropinclass lytic peptide in transgenic mice and subsequent resistance to Brucella abortus

The addition of an antimicrobial that can be synthesized by the mammalian immune system at the point of challenge may enhance disease resistance. A possible group of agents are cecropins, broad-spectrum antimicrobial peptides, which have been described and characterized. They are relatively non-toxic to normal cells from multicellular organisms but are toxic to a wide range of bacteria, protozoa and fungi, as well as infected and abnormal cells. Twenty-six lines of transgenic mice were produced by pronuclear injection of DNA consisting of the 5′-flanking region from −593 to +110 of the mouse interleukin 2 (IL-2) gene, Shiva 1a (a synthetic cecropin-class lytic peptide), and the SV40 polyadenylation/splice signal. A reverse-transcription PCR assay determined that two lines of transgenic mice were produced whose spleen-derived lymphocytes could be induced to transcribe and mature mRNA for Shiva 1a by exposure to 3.25 mg ml−1 of Con A. Two lines were challenged with an inoculation of 5 × 104 Brucella abortus strain 2308. After four weeks, there were significantly fewer B. abortus organisms in the spleens of transgenic mice than in non-transgenic control mice of the same strain (p < 0.05). Since the controlling regions of the IL-2 enhancer and the amino acid sequence of the signal peptide are highly conserved among several species, it is likely that this recombinant gene will function in other mammals

Transfer and Expression of an Artificial Storage Protein (ASP1) Gene in Cassava: Towards Improving Nutritive Value of Storage Roots

Cassava (Manihot esculenta Crantz) is a staple food of more than 500 million people in the tropics. Its storage roots contain starch up to 85% of their dry weight, but are deficient in protein. People depending heavily on cassava may consequently suffer from qualitative malnutrition, unless they can supplement their diet with protein from other sources. Traditional breeding of cassava is difficult due to irregular flowering and low fertility as well as to low seed set and germination rates of the plants, and attempts to improve the protein content of cassava roots have so far been unsuccessful. Advances in plant genetic engineering now provide an alternative to traditional breeding in improving cassava, such as improved root quality and disease resistance.