Low-temperature synthesis of zintl compounds with a single-source molecular precursor

Thermolysis of the heterobimetallic phosphinidene complex [Sb(PCy)3]2- Li6.6HNMe2 (Cy = C6H11) at 303 to 313 kelvin gives Zintl compounds containing (Sb7)3- anions. The complex thus constitutes a stable molecular single-source precursor to Zintl compounds and provides a potential low-temperature route to photoactive alkali metal antimonates. The new chemical reaction involved, which is driven thermodynamically by the formation of P-P bonds, has implications in the low-temperature synthesis of other technologically important materials (such as gallium arsenide).     

Dynamical Signature of the Mott-Hubbard Transition in Ni(S,Se)2

The transition metal chalcogenide Ni(S,Se)2 is one of the few highly correlated, Mott-Hubbard systems without a strong first-order structural distortion that normally cuts off the critical behavior at the metal-insulator transition. The zero-temperature (T) transition was tuned with pressure, and significant deviations were found near the quantum critical point from the usual T1/2 behavior of the conductivity characteristic of electron-electron interactions in the presence of disorder. The transport data for pressure and temperature below 1 kelvin could be collapsed onto a universal scaling curve.     

Buffalo (Bubalus bubali) Late Embryo and Foetus Development: A Morphological Analysis

Many researches describe the embryonic developmental features in domestic animals; however, in farm animals, they are scarce. Most farm animal studies are related to assisted reproduction and embryos transfer techniques. But, morphological features and size measure to estimate the age gestation are rarely reported in literature. Thus, in this study, we described the developmental changes in the bubaline (Bubalus bubali) concepts from 21 to 60 days of gestation. Our results revealed that buffalo embryos similar morphological characteristics similar to other mammalian species. Also, similarities between bovine and bubaline persist; except on foetal stages when buffalos have a faster development than bovine. Therefore, buffalo's gestation period exhibits some varieties and accurate embryo age is more difficult. Yet, when we use a combination of the crown–rump, macroscopic analysis and alizarin red, it is possible to describe better the whole embryogenesis stages of the buffalo and which can contribute for future reproduction researches and applications in veterinary practice.     

Evidence that moxidectin is a greater risk factor than ivermectin in the development of resistance to macrocyclic lactones by Ostertagia spp in sheep in south eastern Australia

AIM: To determine associations between resistance of Ostertagia (= Teladorsagia) spp to macrocyclic lactone (ML) anthelmintics and history of use of anthelmintics, by type, on commercial sheep farms in temperate regions of southern South Australia and Victoria, Australia.

METHODS: Faecal egg count reduction tests (FECRTs) were conducted during a 2.5-year period (from August 2001 to January 2004) and records of the type of anthelmintic used in the 5 years preceding the FECRTs were collected from commercial sheep farms (n=103) in southern South Australia and Victoria, and data analysed retrospectively. ML resistance was defined as <95% reduction of Ostertagia spp 10–14 days after treatment with ivermectin (IVM), orally, at half the manufacturer's recommended dose rate. Use of anthelmintics in the preceding 5 and 10 years on each property was classified according to the nett number of years each of the following classes of drug had been used: IVM oral liquid (IVO), IVM controlled-release capsules (CRCs), abamectin (ABA), moxidectin (MOX) or a non-ML an- thelmintic. The prevalence of ML resistance, by property, was analysed for associations with prior use of anthelmintics.

RESULTS: Resistance by Ostertagia spp to ML anthelmintics was evident on 51/103 (49.5%) properties. The prevalence of resistance was lowest (23%) on properties on which MOX had not been used, and was significantly higher (64–77%) on properties on which MOX had been used for ≥2 of the preceding 5 years (p<0.001). In contrast, the prevalence of resistance was highest (70–74%) on the properties on which IVM, or IVM and/ or ABA, had not been used in the previous 5 years (on which the use of MOX was predominant), and was markedly lower (20– 42%) on properties that had used IVM or IVM and/or ABA for at least one of the preceding 5 years. Prevalence of resistance was higher for properties on which the only ML anthelmintic used was MOX (19/29=66%) than for those on which the only ML used was IVO (2/19=11%; p<0.001). Properties on which the only ML used was MOX were 2.72 times more likely to have resistance than properties on which the only ML used was IVO (95% confidence interval (CI) = 1.01–5.08).

CONCLUSION: Use of MOX for ≥2 of the preceding 5 years was associated with a higher prevalence of resistance to ML by Ostertagia spp on sheep farms in south eastern Australia than the use of IVO.     

Early Development and Putative Primordial Germ Cells Characterization in Dogs

Previously, three distinct populations of putative primordial germ cells (PGCs), namely gonocytes, intermediate cells and pre‐spermatogonia, have been described in the human foetal testis. According to our knowledge, these PGCs have not been studied in any other species. The aim of our study was to identify similar PGC populations in canine embryos. First, we develop a protocol for canine embryo isolation. Following our protocol, 15 canine embryos at 21–25 days of pregnancy were isolated by ovaryhysterectomy surgery. Our data indicate that dramatic changes occur in canine embryo development and PGCs specification between 21 to 25 days of gestation. At that moment, only two PGC populations with distinct morphology can be identified by histological analyses. Cell population 1 presented round nuclei with prominent nucleolus and a high nuclear to cytoplasm ratio, showing gonocyte morphology. Cell population 2 was often localized at the periphery of the testicular cords and presented typical features of PGC. Both germ cell populations were positively immunostained with anti‐human OCT‐4 antibody. However, at day 25, all cells of population 1 reacted positively with OCT‐4, whereas in population 2, fewer cells were positive for this marker. These two PGCs populations present morphological features similar to gonocytes and intermediate cells from human foetal testis. It is expected that a population of pre‐spermatogonia would be observed at later stages of canine foetus development. We also showed that anti‐human OCT‐4 antibody can be useful to identify canine PGC in vivo.     

Absorption by sheep of dieldrin from contaminated soil

Objective To study the accumulation of dieldrin residues in sheep from ingestion of contaminated soils was studied in two experiments.
Design A controlled feeding study of sheep fed contaminated soils of different type at varying intervals.
Animals and procedure Thirty-four 2-years-old wethers were divided into four groups (one control sheep only) and fed water-soluble dieldrin or soil contaminated with aldrin and dieldrin at varying intervals in the first study. In a second study 34 similar sheep were divided into four treatments with one being a control. Sheep were fed sandy, high clay or high organic matter soils with similar dieldrin and aldrin concentrations.
Results In the first study the concentration of dieldrin in the body fat of sheep dosed with dieldrin-contaminated soil was about half that in the body fat of sheep dosed with an equivalent amount of water-soluble dieldrin. The concentration of dieldrin was almost the same in sheep fed 500 μg of total dieldrin per day as it was in sheep fed 5000 μg every tenth day, over a 50-day period. In the second experiment sheep accumu-lated nearly three times as much pesticide from a soil with a high organic matter content, and about four times as much from a soil with a high clay content, as from a sandy soil with the same dieldrin content, over a 100-day period. The half-life of dieldrin in the fat of all sheep varied between 96 and 116 days after sheep ceased ingesting contaminated soil.
Conclusions Dieldrin concentrations in the fat of sheep that consume dieldrin contaminated soil fall within 10 days of removal from the source of contamination. However, dieidrin accumulates in the wool of sheep that consume dieldrin-contaminated soil.