LETHAL FACTORS AND STERILITY

Studies on Hybrid Sterility. II. Localization of Sterility Factors in Drosophila Pseudoobscura Hybrids.

HE causation of hybrid sterility has long been one of the unsolved T problems of biology. To date, probably the greatest advance in this field has been made by FEDERLEY who discovered a failure of the meiotic chromosome pairing in the sterile hybrids between moths of the genus Pygaera. This finding has since been amply corroborated by other investigators in sterile hybrids both in animals and i...

proficiency level and factors fostering reticence in efl learners

according to cheng (1999), in recent esl/efl literature, asian (especially east asian) learners of english as a foreign/second language have been arguably reported as reticent and passive learners. the most common allegations are that these students are reluctant to participate in classroom discourse; they are unwilling to give responses; they do not ask questions; and they are passive and over...

POLYPRENOL REDUCTASE2 Deficiency Is Lethal in Arabidopsis Due to Male Sterility.

Dolichol is a required cofactor for protein glycosylation, the most common posttranslational modification modulating the stability and biological activity of proteins in all eukaryotic cells. We have identified and characterized two genes, PPRD1 and -2, which are orthologous to human SRD5A3 (steroid 5α reductase type 3) and encode polyprenol reductases responsible for conversion of polyprenol t...

Sterility

Sterility in Wheat Hybrids. I. Sterility Relationships and Endosperm Development.

Partial or complete sterility is of frequent occurrence in species crosses. Within the same genus certain species are sterile when crossed while ather combinations are completely fertile. Partial sterility may cause the elimination of certain classes of gametes and prevent desired recombinations of characters in the second generation. Sterility may also cause an abnormal vegetative development....