Concentrations of energy substrates in oviduct fluid in unilaterally ovariectomised pigs

Nichol et al (1992, Journal of Reproduction and Fertility, 96, 699–707) identified a pre- to post-ovulatory decrease (approx 1mM) in the amount of glucose in pig oviduct fluid. The present studies investigated whether the decrease was due to metabolism by embroyos and/or oviduct tissues, and also whether there was a local influence of the ovary on the oviduct fluid content of energy substrates. Unilaterally ovariectomised pigs were used, in which, through compensation, oviducts that contained twice the normal number of embryos could be compared with oviducts which contained no embryos. Following unilateral ovariectomy and after two oestrous cycles of normal duration, surgery was performed 88 hours after the beginning of standing heat to obtain oviduct fluid samples, just before embryonic entry into the uterus. Luminal fluid samples from the ampulla and ampullary-isthmic junction from oviducts with and without an adjacent ovary were assayed for glucose, pyruvate and lactate concentrations. No significant differences were found between the glucose, pyruvate and lactate concentrations in fluids from the ampulla or ampullaryisthmic junction from oviducts containing embryos compared with absence of embryos (P> 0·05). Therefore, the post-ovulatory decrease was not due to the presence of embryos or to a local effect of the ipsilateral ovary. Consequently, pig oviduct fluid concentrations of glucose, lactate and pyruvate are seemingly regulated by systemic mechanisms.     

Influence of Ovulation Status,Seasonality and Embryo Transfer Method on Development of Cloned Porcine Embryos

To improve pig cloning efficiency, the present study evaluated the effect of ovulation status, seasonality and embryo transfer (ET) method on in vivo development of cloned porcine embryos. Cloned embryos were transferred to surrogate mothers on the same day of somatic cell nuclear transfer. In pre‐ovulation stage (PO), pregnancy rate (PR) and delivery rate (DR) were 36.3% and 9.4%, respectively. In post‐ovulation stage, 22.7% PR and 2.1% DR were recorded (both PR and DR are significantly higher in PO). When ET was performed during winter (December–February), spring (March–May), summer (June–August) and autumn (September–November), the PRs were 13.4%, 37.3%, 24.6% and 51.0%, while DRs were 0%, 12.7%, 4.3% and 7.8%, respectively. The highest PRs were recorded in autumn groups. However, DRs were significantly lower in autumn (7.8%) group compared with spring (12.7%) group. The PR was the lowest and no piglets were born in winter group, which might be because of the effect of low temperature during ET. To overcome the low PR in winter group, 0.25 ml straws were used for ET to minimize exposure time of embryos to ambient temperature. The straw ET group showed significantly higher PR in the winter group (23. 9%) compared with the conventional catheter‐loading group (7.7%). We suggest that using PO recipient and ET in spring is the best condition for pig cloning. In addition, alternative method to reduce cold shock during ET in winter is necessary.     

Artificial Insemination of Swine: Fecundity of Boar Semen Stored in Beltsville TS (BTS), Modified Modena (MM), or MR-A and Inseminated on One,Three and Four Days After Collection12

Contents: A field trial was conducted on 1,463 farms in The Netherlands to compare the fertilizing capacity of boar spermatozoa extended in Beltsville TS (BTS), Modified (MM), or MR-A, and inseminated in 2896 sows and gilts on the first, third or fourth day following collection. Semen was collected, extended, and stored at 18°C at six different AI centers and inseminated by inseminators on their regular routes. Sows inseminated with BTS and MR-A extended semen had higher farrowing rates than MM (79.3, 77.6 us 50.4, P <.0001), higher total pigs per litter (11.4, 11.1 vs 10.0, P <.0001) and higher total pigs born alive (10.7, 10.5 vs 9.4, P <. 0001). The farrowing rate of gilts inseminated with BTS extended semen was superior to MM (73.5 vs. 50.2%, P <.004), while MR-A gave farrowing rates greater than MM (64.1 vs 50.2%, P =.06). There was no difference in litter data for gilts. Farrowing rates for 1 and 4 day semen were superior to 3 day semen (73.2, 73.8 vs 60.3, P <.0001). The semen inseminated on day 4 contained 6 billion sperm per dose rather than the 3 billion per dose for 1 and 3 day semen. Based on the results of this study, BTS and MR-A are effective diluents for extension and storage of boar semen for use within the same week of collection. In addition, semen extended in either BTS of MR-A and stored and inseminated on the fourth day after collection can give fertility equal to first day insemination if the sperm per insemination dose is doubled. Inhalt: Künstliche Besamung beim Schwein: Fruchtbarkeitsergebnisse von Ebersamen nach Flussigkonservierung mit BTS, MR-A oder modifiziertem Modena-Verdünner (MM) und Besamung am ersten, dritten und vierten Tag nach Samengewinnung In einem in den Niederlanden durchgeführten Feldversuch wurden 3 verschiedene Verdünner-Medien für Ebersamen in vivo verglichen. Die Medien waren Beltsville TS (BTS), modifizierter Modena-Verdünner (MM) und das spanische MR-A-Medium. Insgesamt wurden 2896 Jung- und Altsauen in 1463 Herden mit 1, 3 oder 4 Tage altem Sperma besamt. Der Versuch wurde als “split-sample”-Versuch an 6 Eberstationen durchgeführt, der verdunnte Samen bei + 18°Cgelagert und von den Besamungsbeauftragten im Rahmen ihrer regulären Fahrten eingesetzt. BTS- und MR-A-konserviertes Sperma gab bei Altsauen gegenüber MM höhere Abferkelraten (79,3, 77,6 vs 50,4%, P < 0.0001), eine höhere totale Wurfzahl (11,4, 11,1 vs 10,0, P < 0.0001) und eine höhere Anzahl lebendgeborener Ferkel)10,7, 10,5 vs 9,4, P < 0.0001). Die mit BTS-uerdünntem Samen inseminierten Jungsauen wiesen gegenüber MM höhere Abferkelraten auf(73.5 vs 50,2%, P < 0.004). MR-A-Sperma lag ebenfalls hüher als MM-Samen (641 vs 50,2%, P=0.06). Die Wurfgröβen der Jungsauen reigten keine Unterschiede. Die Abferkelergebnisse nach Besamung mit 1 und 4 Tage altem Samen lagen höher als die des 3 rage alten Spermas (73,2, 73,8 vs 60,3%; P < 0.0001). Die am Tag 4 verwendeten Samenportionen enthielten 6 Milliarden Spermien gegenüber 3 Milliarden der nach 1 bzw. 3 Tagen inseminierten Portionen. Die Ergebnkse dieses Versuches zeigen, daβ BTS und MR-A effektive Verdünnermedien sind und die Lagerung von Eberfrischsperma zum Einsatz innerhalb der Entnahmewoche ermoglichen. Darüber hinaus können mit BTS oder MR-A verdünntes und am Tag 4 nach Gewinnung eingesetrtes Sperma Fruchtbarkeitsergebnisse erzielt werden, die ebenso gut sind wie nach Verwendung des 1-Tage-Spermas, wenn die Spermienzahl pro Besamungsdosis verdoppelt wird.     

Management of interactions between endangered species using habitat restoration

Commonly used conservation strategies may be insufficient when deleterious interactions between co-habiting endemic species occur. The decline in the population size of the endangered Leon Springs pupfish, Cyprinodon bovinus, in Diamond Y Spring, Texas has been partially attributed to egg-predation by the endangered Pecos gambusia, Gambusia nobilis. This interaction is related to changes in habitat availability; therefore, we aim to manage the conflict via restoration of the breeding habitat. We hypothesized that altering the habitat to expand shallow breeding areas would result in a decrease in the number of gambusia preying on the eggs of spawning pupfish pairs and an increase in the number of males defending territories. In 2 years following the habitat modification, we observed resurgence in the pupfish breeding population and a decrease in egg-predation pressure around spawning pupfish pairs. Additionally, after altering the habitat, gambusia were more dispersed throughout the habitat, as the low numbers of gambusia in a territory were stable regardless of spawning or aggressive behaviors by pupfish. To our knowledge, this is the first empirical example of effective management of deleterious interactions between two endangered species by means of habitat restoration.     

Triazole fungicides and the selection of resistance to medical triazoles in the opportunistic mould Aspergillus fumigatus

Azole resistance is an emerging problem in the opportunistic mould Aspergillus fumigatus. The triazoles are the most important agents for the management of Aspergillus diseases in humans. Selection for acquired resistance may occur in the hospital setting through exposure to high doses of azoles during azole therapy, but evidence is accumulating that A. fumigatus may become resistant to medical triazoles through environmental exposure to fungicides. The recovery of A. fumigatus isolates resistant to the medical triazoles from azole‐naive patients as well as from the environment strongly indicates an environmental route of resistance selection. Molecule alignment studies have identified five fungicides that share a very similar molecule structure with the medical triazoles, and thus may have selected for mechanisms that confer resistance to both groups of compounds. It is important to explore further the presumed fungicide‐driven route of resistance selection in order to implement effective preventive measures as the prevalence of azole resistance in A. fumigatus continues to increase and causes major challenges in the management of azole‐resistant Aspergillus diseases. Copyright © 2012 Society of Chemical Industry     

对推行兽药GMP工作的思考

对推行实施兽药GMP工作中存在的问题进行了分析,提出了建议和对策,并指出兽药行业的规范化管理,除了要推行实施兽药GMP外,还应加快对兽药的经营、使用、研发、临床试验等各环节的立法,建立健全机构,加强队伍建设,特别是要尽快推行兽药经营质量管理规范(GSP),否则兽药GMP将很难长期坚持下去.     

Defects in semiconductors: some fatal, some vital

REVIEW The role of defects as essential entities in semiconductor materials is reviewed. Early experiments with semiconductors were hampered by the extreme sensitivity of the electronic properties to minute concentrations of impurities. Semiconductors were viewed as a family of solids with irreproducible properties. Scientific efforts overcame this idiosyncrasy and turned the art of impurity doping into today's exceedingly useful and reproducible technology that is used to control precisely electrical conductivity, composition, and minority-carrier lifetimes over wide ranges. Native defects such as vacancies and self-interstitials control basic processes, foremost self- and dopant diffusion. The structural properties of dislocations and higher dimensional defects have been studied with atomic resolution, but a thorough theoretical understanding of their electronic properties is incomplete. Reactions between defects within the host lattices are increasingly better understood and are used for gettering and electrical passivation of unwanted impurities. Metastable defects such as DX centers and the EL2-related arsenic antisite are briefly discussed. The recent development of isotopically controlled semiconductors has created new research opportunities in this field.     

Complex Shear Wave Velocity Structure Imaged Beneath Africa and Iceland

A model of three-dimensional shear wave velocity variations in the mantle reveals a tilted low velocity anomaly extending from the core-mantle boundary (CMB) region beneath the southeastern Atlantic Ocean into the upper mantle beneath eastern Africa. This anomaly suggests that Cenozoic flood basalt volcanism in the Afar region and active rifting beneath the East African Rift is linked to an extensive thermal anomaly at the CMB more than 45 degrees away. In contrast, a low velocity anomaly beneath Iceland is confined to the upper mantle.     

Colliding beam fusion reactor

Recent results with Tokamak experiments provide insights into the problem of magnetic confinement. They demonstrate how to avoid anomalous transport and thus solve the major problems of Tokamak reactors: size, the production of 14-megaelectron volt neutrons, and maintenance. An alternate confinement system, the field-reversed configuration, confines beams of protons and boron-11. For the proton-boron-11 fusion reaction, the fusion products are all charged particles for which direct conversion is feasible and neutron flux is negligible.