Oxytocin maintains as well as initiates female sexual behavior: effects of a highly selective oxytocin antagonist

In previous studies, central administration of the oxytocin (OT) antagonist d(CH2)5[Tyr(Me)2, Thr4, Tyr-NH(9)2]OVT (OTA1) blocked receptive and proceptive components of female sexual behavior (FSB) and increased male-directed agonistic behavior when given before progesterone (P) treatment in estradiol-primed female rats but not when given shortly before behavioral testing 4-6 h after P. Because the considerable V(1a) antagonist potency of OTA1 may have contributed to these results, we tested the effects of the far more selective OT antagonist desGly-NH2, d(CH2)5[d-Tyr2, Thr4]OVT (OTA2). In ovariectomized, estradiol benzoate-primed (1 microg x 2 days sc) rats, icv infusion of OTA2 (1 microg) prior to P injection (250 microg sc) significantly suppressed lordosis and hops and darts and trended toward significantly increasing male-directed kicks during testing at 4 and 6 h. Infusion of OTA2 3 h and 40 min after P did not alter behavior at 4 and 6 h after P but significantly decreased lordosis as well as hops and darts and increased male-directed kicks 8-12 h after P. These results provide further evidence that central OT receptor activation shortly after P treatment contributes to the subsequent onset and early expression of FSB and demonstrate, for the first time, that OT receptor activation at later time points also contributes to maintaining FSB. The FSB-stimulating effect of central OT appears to persist for several hours.     

Crystal structure of beta 1,3-glucuronyltransferase I in complex with active donor substrate UDP-GlcUA

Beta1,3-glucuronyltransferase (GlcAT-I) is an essential enzyme involved in heparan sulfate and chondroitin sulfate biosynthesis. GlcAT-I is an inverting glycosyltransferase that catalyzes the transfer of glucuronic acid (GlcUA) to the common growing linker region Galbeta1-3Galbeta1-4Xyl that is attached to a serine side chain of a core protein. Previously the structure of GlcAT-I has been solved in the presence of the donor product UDP and an acceptor analog Galbeta1-3Galbeta1-4Xyl (Pedersen, L. C., Tsuchida, K., Kitagawa, H., Sugahara, K., Darden, T. A. & Negishi, M. (2000) J. Biol. Chem. 275, 34580-34585). Here we report the x-ray crystal structure of GlcAT-I in complex with the complete donor UDP-GlcUA, thereby providing structures of an inverting glycosyltransferase in which both the complete donor and acceptor substrates are present in the active site. This structure supports the in-line displacement reaction mechanism previously proposed. It also provides information on the essential amino acid residues that determine donor substrate specificity.     

Conservation genetics of peripheral populations of the mygalomorph spider Atypus affinis (Atypidae) in northern Europe

Genetic diversity and differentiation were studied in peripheral populations of the recently rediscovered purse-web spider Atypus affinis in Denmark and Sweden using allozyme electrophoresis. Because of the very narrow environmental niche exploited by this species, only a limited number of potential habitats are available. Furthermore, fragmentation has reduced the number and size of potential habitats within the last century. The level of genetic diversity in A. affinis was intermediate compared with other nonsocial spiders, but low compared with invertebrates in general. Significant genetic differentiation was found within distances of only 1-10 km with FST estimates ranging from 0.020 to 0.075. Within distances of 30-60 km FST ranged from 0.081 to 0.312. Hierarchical FST revealed that genetic variability was partitioned at 89.8% within populations, 9.5% among populations within regions and only 0.7% among the four main regions in Denmark and Sweden. Comparing the result of the genetic analysis with the life history of A. affinis, it is concluded that the level of successful dispersal is low, and that the species has not recently reinvaded northern Europe but prevailed undiscovered for several decades. Finally, it is suggested that the genetic scenario found for A. affinis might represent that for a wide range of other arthropods with similar life history characteristics.     

Local evolution of obligate autogamy inEpipactis helleborine subsp.neerlandica (Orchidaceae)

Isozyme analysis was used to assess the origin of the DanishEpipactis renzii, a local endemic of open coastal dunes. It seems to have evolved recently in several local populations of the more or less allogamousE. helleborine subsp.neerlandica. The obligately autogamousE. renzii is restricted to the easternmost part of the Danish range ofE. helleborine subsp.neerlandica, indicating that transition to obligate autogamy has been a selective advantage in that area. This may be explained by water stress, caused by a higher evapotranspiration (cf. the mean temperature of July which increases towards the east) — obligate autogamy shortens the time span from anthesis to fruit set due to a rapid pollination process. We propose thatE. renzii should only be recognized as a variety ofE. helleborine subsp.neerlandica.     

Timetable of in vivo embryonic development in the grey short-tailed opossum (Monodelphis domestica)

The timing of development was examined in 496 embryos from female Monodelphis domestica, collected at known time intervals after video recorded mating. Ovulation occurred approximately 20 hr (day 1) after mating, and fertilization was observed by 24 hr. Transport through the oviducts was rapid, and pronuclear stage embryos were recovered from the uterus as early as 24 hr after mating. Second cleavage had occurred by 55 hr after mating. Three-celled embryos were among those collected on day 3 after mating, indicating that asynchronous cleavage of blastomeres can occur from the two-cell stage. The four-cell stage persisted for approximately 24 hr, and embryos that had undergone third cleavage were first recovered 74 hr after mating. Embryos that had undergone fourth to fifth cleavage were found 96–100 hr (4 days) after mating and complete unilaminar blastocysts by 5.5 days after mating. Primary endoderm formed from an already distinct embryonic area of the unilaminar blastocyst early on day 7 after mating. Formation of the bilaminar blastocyst was completed rapidly, on day 7 after mating. The primitive streak appeared on day 10 after mating, and organogenesis rapidly ensued on a timetable similar to that reported for Didelphis virginiana (McCrady, 1938). Close contact with the maternal circulation was established on day 11 and by day 12 maternal and embryonic tissues could not be separated without damage. The length of the gestation period from fertilization to birth was approximately 13.5 days. These observations provide the basis for further embryological cellular and molecular studies of this species as a laboratory model for marsupial development.© 1994 Wiley-Liss, Inc.     

Rapid radiometric detection of mycobacterial growth from smear-positive tissue samples from pigs

Rapid demonstration of mycobacteria in slaughter pigs is important for medical, epidemiological and economic reasons. The Bactec radiometric system detected more mycobacteria in less time than conventional culture on solid medium.