Immune response to calf collagen type I in mice: A combined control ofIr-1A and nonH-2 linked genes

The genetically controlled immune response to calf skin collagen type I in mice could be demonstrated to be governed by at least two genes. One is linked to theH-2 complex and located within theIA subregion. High-responder alleles areH-2 ^b ,H-2 ^f , andH-2 ^s . The other gene(s) is not linked to theH-2 complex and high-responder allele(s) are found in the genome of B10 mice but not in the genome of DBA mice. There are strong indications that theIr-1A gene controls the response at the T-cell level, whereas it is assumed that the background gene(s) control the immune response at a different level.     

In vitro fertilization and seed development inTrifolium

Summary Pistils ofTrifolium repens L. andT. ambiguum Bieb. were cultured on an agar-based modified Murashige-Skoog medium. Pistils with and without accessory floral parts were removed from flowers of selected clones ofT. repens, hand-pollinated under aseptic conditions, and planted on the medium. Pistils cultured without accessory floral parts showed no evidence of fertilization after 2 weeks. However, 52% of thoseT. repens pistils cultured with calyx lobes and pedicels contained ovules with maturing embryos 12 days after in vitro cross-pollination. Pistils fromT. ambiguum intraspecific cross-pollinations could not be cultured successfully under the same conditions; however, addition of various combinations of auxin, cytokinin, and gibberellic acid enhanced embryo growth. Fertilization and partial embryo development occurred in interspecific crosses betweenT. ambiguum andT. repens orT. hybridum only whenT. ambiguum was used as the pistillate parent. These results indicate that embryological development under in vitro conditions closely parallels in situ development although growth regulator requirements may vary among species. This work is Technical Contribution 1785 from the South Carolina Agricultural Experiment Station and was supported by SCAES-USDA Cooperative State Research Agreement No. 616-15-65.     

Botanische Mittheilungen

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