Toxicological Studies of Irradiated Pollen for Medicinal Use

The toxicity and mutagenicity of irradiated pollen were studied. Its oral LD50 value was＞21,500 mg/kg for both malc and female mice. Mutagenicity assays were studied by three short-term tests. Ames test showed that irradiated pollen did not induce any mutation of the strains TA97, TA98, TA100 and TA102. Micronucleus test on the bone marrow cells of mice showed no significant difference in the percentages of polychromatic erythrocytes with micronuclei between the exposed groups and the control. Chromosomal test on the reproduction cells of mice showed no change on the chromosomal aberration rate. These results demonstrate that irradiated pollen is safe for medicinal use.

Distinguishment of A 42 Capsomere Structure of Icosohedral Virion from A 32 One by Electron Microsco

It is difficult to define the exact number of capsomeres of an icosohed ral virion by electrun microscope due to their relatinely small size.While the results suggest a 42 vr a 32 cap-somere sructure one can't dusting uish between these twu pussibiltues.It owever in morphological study of a new nirus which was tempurarily named Rabbit Hemerthagic V'rrus we have proved that when the 5-fuld symmetry az is is perpend cular to the plane of the paper with the observable peripheral capomeres of an iusuhedral nirion,one can disting uish a 42 frum a 32 capsomere structure by elec-tron muruxrupe.Then we oblarned the exact rumber of capsumeres of Rabbit Ilemorrhagic V'irus.t.e.the pariom capsid smade of 42 capsumeres.

Mass Production of Intergeneric Chromosomal Translocations through Pollen Irradiation of Triticum durum-Haynaldia villosa Amphiploid

Haynaldia villosa possesses a lot of important agronomic traits and has been a powerful gene resource for wheat improvement. However, only several wheat-H, villosa translocation lines have been reported so far. In this study, we attempted to develop an efficient method for inducing wheat-H, villosa chromosomal translocations. Triticum durum- Haynaldia villosa amphiploid pollen treated with 1 200 rad ^60Co-y-rays was pollinated to Triticum aestivum cv. ＇Chinese Spring＇. Ninety-eight intergeneric translocated chromosomes between T. durum and H. villosa were detected by genomic in situ hybridization in 44 of 61 M1 plants, indicating a translocation occurrence frequency of 72.1%; much higher than ever reported. There were 26, 62 and 10 translocated chromosomes involving whole arm translocations, terminal translocations, and intercarlary translocations, respectively. Of the total 108 breakage-fusion events, 79 involved interstitial regions and 29 involved centric regions. The ratio of small segment terminal translocations （W.W-V） was much higher than that of large segment terminal translocations （W-V.V）. All of the M1 plants were self-sterile, and their backcross progeny was all obtained with ＇Chinese Spring＇ as pollen donors. Transmission analysis showed that most of the translocations were transmittable. This study provides a new strategy for rapid mass production of wheat-alien chromosomal translocations, especially terminal translocations that will be more significant for wheat improvement.

Induction and transmission of wheat-Haynaldia villosa chromosomal translocations

In order to develop more wheat-Haynaldia villosa translocations involving different chromosomes and chromosome segments of H. villosa, T. durum-H, villosa amphiploid was irradiated with ^60Co γ-rays at doses of 800, 1,200, and 1,600 rad. Pollen collected from the spikes 1, 2, and 3 days after irradiation were transferred to emasculated spikes of the common wheat cv. ‘Chinese Spring＇. Genomic in situ hybridization was used to identify wheat-H, villosa chromosome translocations in the M1 generation. Transmission of the identified translocation chromosomes was analyzed in the BC1, BC2, and BC3 generations. The results indicated that all three irradiation doses were highly efficient for inducing wheat-alien translocations without affecting the viability of the M1 seeds. Within the range of 800-1,600 rad, both the efficiency of translocation induction and the frequency of interstitial chromosome breakage-fusion increased as the irradiation dosage increased. A higher translocation induction frequency was observed using pollen collected from the spikes 1 day after irradiation over that of 2 or 3 days after irradiation. More than 70% of the translocations detected in the M1 generation were transmitted to the BC1 through the female gametes. All translocations recovered in the BC1 generation were recovered in the following BC2, and BC3 generations. The transmission ability of different translocation types in different genetic backgrounds showed an order of ‘whole-arm translocation 〉 small alien segment translocation 〉 large alien segment translocation＇, through either male or female gametes, In general, the transmission ability through the female gametes was higher than that through the male gametes. By this approach, 14 translocation lines that involved different H. villosa chromosomes have been identified in the BC3 using EST-STS markers, and eight of them were homozygous.