A comparison of sperm morphology and silver nitrate staining characteristics in the domestic ferret and the black-footed ferret

Ejaculated sperm from the domestic ferret (Mustela putorius furo) and the black-footed ferret (Mustela nigripes) were compared for differences in morphological abnormalities and argentophilic protein distribution. Thawed domestic ferret sperm was also compared to fresh sperm to determine whether there were any effects on cell morphology due to cryopreservation. There were statistically significant differences between the two species of ferret in two of the categories scored. The domestic ferret had a higher frequency of cells that were bent in the midpiece and in the principal piece, and a higher frequency of headless and tailless cells when compared to the black-footed ferret. There were no statistically significant differences in cell morphology between the fresh and cryopreserved ejaculates of the domestic ferret employing a standard egg yolk cryoextender. Silver nitrate staining distribution was different between the two species in both the head and tail region.     

A fast and sensitive multiple sequence alignment algorithm

A two-step multiple alignment strategy is presented that allowsrapid alignment of a set of homologous sequences and comparisonof pre-aligned groups of sequences. Examples are given demonstratingthe improvement in the quality of alignments when comparingentire groups instead of single sequences. The modular designof computer programs based on this algorithm allows for storageof aligned sequences and successive alignment of any numberof sequences. Received on August 23, 1988; accepted on December 6, 1988     

Preparation and characterization of cell-free protein synthesis systems from oocytes and eggs of Xenopus laevis

During the maturation of the oocytes of the frog Xenopus laevis, the rate of protein synthesis shows a twofold increase. Studies of the mechanisms involved in this stimulation have been seriously limited by the lack of an active cell-free translation system. We have now prepared such systems from oocytes, progesterone-matured oocytes and eggs of Xenopus laevis by induction of lysis by centrifugation of whole cells. The extracts are highly active in incorporation of labelled amino acids and, in the progesterone-matured and egg extracts, a substantial proportion of this is due to reinitiation on endogenous mRNA, as shown by the use of inhibitors. The increased rate of protein synthesis previously observed in intact oocytes following progesterone-induced maturation is reflected in the relative activities of the extracts. The difference in activity is not due to the presence of a dominant inhibitor of translation in the extracts from unstimulated oocytes. Labelling studies with initiator tRNA ([35S]Met-tRNAf) indicate a higher concentration of 43S preinitiation complexes in the extracts from unstimulated oocytes, suggesting an impairment of initiation of translation at or after the mRNA-binding step. Extracts from both oocytes and progesterone-matured oocytes translated endogenous mRNAs to give products ranging over a wide spectrum of molecular weight. However, significant translation of exogenous (globin) mRNA required the presence of reticulocyte postribosomal supernatant, suggesting that one or more factors required for mRNA recruitment is limiting in these extracts.