Lectin‐Binding Pattern in Ovarian Structures of Rats with Experimental Polycystic Ovaries

Numerous experimental models in different species have been developed for the study of polycystic ovarian syndrome. In this study, we used a model of induction of polycystic ovaries (PO) in rats by exposure to constant light to study the distribution and variations of glycosylated residues present in the different ovarian structures. Seven biotinylated lectins were used (Con‐A, WGA, DBA, SBA, PNA, RCA and UEA‐I) on tissue sections, and detection was performed using the streptavidin/peroxidase method. In tissue sections was observed an increase in affinity for Con‐A in the granulosa and theca interna of growing follicles and cysts in animals with PO in relation to the control group. Follicular cysts showed higher affinity for WGA and RCA‐I which growing follicles in the same group, and there was a decrease in affinity for PNA in the cysts in relation to the growth of follicles in both groups. Atretic follicles in both groups showed greater labelling with lectins PNA, SBA and RCA‐I in relation to healthy follicles. It could also be noted that the zona pellucida of cystic follicles lost the affinity for the lectin Con‐A. There was no staining on follicles in any category with the lectins DBA and UEA‐I, although it was staining in the corpus luteum (control group) and in the mesothelium and interstitial glands of both groups with DBA. These observations probably reflect changes in the glycosaminoglycans present in the different ovarian compartments or in the glycosylation of cellular components essential for proper follicular dynamics.     

Production of Oocytes of Nile Tilapia (Oreochromis niloticus) for In Vitro Fertilization via Hormonal Treatments

Only a few studies have described hormonal treatments for induction of synchronicity and gamete collection in Nile tilapia (Oreochromis niloticus), both important for assortative matings in breeding programmes and essential for polyploidy technologies. In this study, we compared the effectiveness of carp pituitary extract (CPE), Nile tilapia pituitary extract (TPE), human chorionic gonadotropin (hCG) and gonadotropin‐releasing hormone (GnRH) protocols on the induction of spawning and egg production in Nile tilapia. Among the hormonal treatments analysed, only hCG was effective for producing viable gametes for in vitro fertilization. To verify the viability of this hormonal treatment, hCG was tested using different doses (1000, 2000, 3000, 4000 and 5000 IU/kg) in a large number of females (208 animals) from two Nile tilapia lines. The results indicated that hCG doses between 1000 and 5000 IU/kg could be used to induce final oocyte maturation in Nile tilapia with collection of stripped oocytes. This is the first study to report differential reproductive responses to hormonal treatment between tilapia lines: line 1 was more efficient at producing eggs and post‐hatching larvae after hCG induction than line 2. In conclusion, we demonstrated that the hCG protocol may be applied on a large scale to induce final oocyte maturation in Nile tilapia. The development of a protocol for in vitro fertilization in Nile tilapia may aid in breeding programmes and biotechnological assays for the development of genetically modified lines of Nile tilapia.     

The in vitro response of field strains of sheep blowflies Lucilia sericata and L. cuprina (Calliphoridae) in New Zealand to dicyclanil and triflumuron

AIM: To evaluate the in vitro efficacy of triflumuron and dicyclanil against field strains of Lucilia sericata and L. cuprina in New Zealand to establish whether anecdotal reports of declining protection periods afforded by dips containing these active ingredients had validity.

METHODS: Strains of field-derived blowflies (Lucilia cuprina and L. sericata) were obtained from adult flies from flytraps or larvae from sheep with flystrike submitted from seven regions of the North and two regions of the South Islands of New Zealand. A total of 27 strains of L. sericata and 19 of L. cuprina were established in culture and first instar larvae obtained were exposed in vitro to dilution series of technical-grade dicyclanil (a pyrimidine carbonitrile) and triflumuron (a benzoyl urea). Concentrations lethal to 50% (LC₅₀) and 95% (LC₉₅) of each strain were calculated and tested by probit analysis, with the ratio of LC₅₀ of each strain divided by LC₅₀ of the most susceptible strain (resistance factor) derived in order to facilitate between-strain comparisons of susceptibility.

RESULTS: There was considerable variation between strains of L. sericata larvae in their susceptibility to triflumuron, with those least susceptible originating from the Waikato region. Strains from both Tararua and Manawatu regions were most susceptible and East Coast strains intermediate. All strains of the species tested showed a narrow band of susceptibility to dicyclanil with no regional trends apparent.

CONCLUSIONS: Representative field-strains of sheep blowflies exhibited a range of susceptibilities to both triflumuron and dicyclanil, suggestive of both genetic heterogeneity among fly populations and the spectrum of dip use in their source areas. This means there should be concerns for the long-term benefits of benzoyl urea insecticides for sheep farmers in New Zealand, but not yet for dicyclanil-based formulations.

CLINICAL RELEVANCE: Flystrike is a debilitating and occasionally lethal disease in sheep such that efficacious sheep dips have prophylactic value in reducing the prevalence of the condition.     

The effect of moderate hypovolemia on cardiopulmonary function in dogs

Objective: To collate canine cardiopulmonary measurements from previously published and unpublished studies in instrumented, unsedated, normovolemic and moderately hypovolemic dogs. Design: Collation of data obtained from original investigations in our research laboratory. Setting: Research laboratory, School of Veterinary Medicine. Subjects: Sixty‐eight dogs. Interventions: Subjects were percutaneously instrumented with an arterial catheter and a thermodilution cardiac output catheter. A femoral artery catheter was percutaneously placed for blood removal. Measurements and main results: Body weight, arterial and mixed‐venous pH and blood gases, arterial, pulmonary arterial, pulmonary artery occlusion, and central venous blood pressure, cardiac output, and core body temperature were measured. Body surface area, bicarbonate concentration, standard base excess, cardiac index (CI), stroke volume, systemic and pulmonary vascular resistance, left and right ventricular work and stroke work indices, left and right rate‐pressure product, alveolar PO₂, alveolar–arterial PO₂ gradient, arterial and mixed‐venous and pulmonary capillary oxygen content, oxygen delivery, oxygen consumption, oxygen extraction, venous admixture, arterial and venous blood carbon dioxide content, arterial–venous carbon dioxide gradient, carbon dioxide production were calculated. In 68 dogs, hypovolemia sufficient to decrease mean arterial blood pressure (ABPm) to an average of 62 mmHg, was associated with the following changes: arterial partial pressure of carbon dioxide (PaCO₂) decreased from 40.0 to 32.9 mmHg; arterial base deficit (BDa) increased from ?2.2 to ?6.3 mEq/L; lactate increased from 0.85 to 10.7 mm /L, and arterial pH (pHa) did not change. Arterial partial pressure of oxygen (PaO₂) increased from 100.5 to 108.3 mmHg while mixed‐venous PO₂ (PmvO₂) decreased from 49.1 to 34.1 mmHg. Arterial and mixed‐venous oxygen content (CaO₂ and CmvO₂) decreased from 17.5 to 16.5 and 13.8 to 9.6 mL/dL, respectively. The alveolar–arterial PO₂ gradient (A‐a PO₂) increased from 5.5 to 8.9 mmHg while venous admixture decreased from 2.9% to 1.4%. The ABPm decreased from 100 to 62 mmHg; pulmonary arterial pressure (PAPm) decreased from 13.6 to 6.4 mmHg; and pulmonary arterial occlusion pressure (PAOP) decreased from 4.9 to 0.1 mmHg. CI decreased from 4.31 to 2.02 L/min/m². Systemic and pulmonary vascular resistance (SVRI and PVRI) increased from 1962 to 2753 and 189 to 269 dyn s/cm⁵, respectively. Oxygen delivery (DO₂) decreased from 787 to 340 mL/min/m² while oxygen consumption (VO₂) decreased from 172 to 141 mL/min/m². Oxygen extraction increased from 20.9% to 42.3%. Conclusions: Moderate hypovolemia caused CI and oxygen delivery to decrease to 47% and 42% of baseline. Oxygen extraction, however, doubled and, therefore, oxygen consumption decreased only to 82% of baseline.     

Synthesis and fungicidal activity of 1,4-dithiino[2,3-b]quinoxaline-2,3-dicarbonitriles

A series of eleven 1,4-dithiino[2,3-b]quinoxaline-2,3-dicarbonitriles was prepared by reaction of 2,3-dichloroquinoxalines with disodium (2)-2,3-dimercapto-2-butenedinitrile in N,N-dimethylformamide. These products were tested for in-vitro fungicidal activity by a Minimum Inhibitory Concentration (MIC) method. Several of these compounds showed broad-spectrum fungicidal activity. The activity exhibited by these compounds was greatly dependent upon the substituents of the quinoxaline ring, with the nitro-substituted derivatives showing the highest levels of antifungal activity. None of the compounds prepared, however, showed fungicidal activity comparable to that of the commercial fungicides screened.     

Impacts of rising atmospheric carbon dioxide on model terrestrial ecosystems

In model terrestrial ecosystems maintained for three plant generations at elevated concentrations of atmospheric carbon dioxide, increases in photosynthetically fixed carbon were allocated below ground, raising concentrations of dissolved organic carbon in soil. These effects were then transmitted up the decomposer food chain. Soil microbial biomass was unaffected, but the composition of soil fungal species changed, with increases in rates of cellulose decomposition. There were also changes in the abundance and species composition of Collembola, fungal-feeding arthropods. These results have implications for long-term feedback processes in soil ecosystems that are subject to rising global atmospheric carbon dioxide concentrations.