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.     

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.     

Phase-matched generation of coherent soft X-rays

Phase-matched harmonic conversion of visible laser light into soft x-rays was demonstrated. The recently developed technique of guided-wave frequency conversion was used to upshift light from 800 nanometers to the range from 17 to 32 nanometers. This process increased the coherent x-ray output by factors of 10(2) to 10(3) compared to the non-phase-matched case. This source uses a small-scale (sub-millijoule) high repetition-rate laser and will enable a wide variety of new experimental investigations in linear and nonlinear x-ray science.     

Lectin‐binding Sites on the Normal and Pathologic Uterus of Sows

The lectin‐binding pattern was compared in the normal and pathological uterus of sows during the ovarian cycle. The following biotinylated lectins were used: Con A, DBA, SBA, PNA, RCA‐I, UEA‐I and WGA. Glycoconjugate labelling showed differences between phases of ovarian cycle and presence of morphologic lesions. Cystic endometrial hyperplasia increased the RCA‐I reaction in the apical region of the glandular epithelium. There was higher intensity of labelling of WGA in the glandular epithelium in uteri with endometritis. In addition, increased Con A binding in the glandular epithelium and mild reduction of UEA‐I reactivity in the glycocalyx of the glandular epithelium were detected in the cases of endometritis. The results of this study show that morphologic alterations modify the sugar pattern in the porcine uterus. These modifications in glycoconjugates may be one of the reasons for decreased fertility in sows.     

Intermediate Filament Proteins Expression and Carbohydrate Moieties in Trophoblast and Decidual Cells of Mature Cat Placenta

The aim of this study was to characterize cytoskeletal intermediate filament proteins and glycoconjugates of syncytiotrophoblast, cytotrophoblast and decidual cells of feline endotheliochorial placenta. Samples from 12 normal pregnant female cats, after 45 ± 5 days of gestation, were obtained removing the uterine horns by hysterectomy. Sections were processed for routine observation and for immunohistochemistry using anticytokeratin, antivimentin and antidesmin antibodies. In addition, lectin histochemistry was performed using a panel of several biotinylated lectins to characterize glycosides expression profile. Cytotrophoblast and syncytiotrophoblast showed immunoreactivity only with acidic and basic cytokeratins. Decidual cells were only positive to vimentin, consistent with their origin from endometrial fibroblasts. Trophoblast expressed a broad population of glycans, highly exposing terminal N‐acetyl glucosamine residues and non‐sialylated galactose and N‐acetyl galactosamine oligomers. Oligosaccharides bound by Phaseolus vulgaris erythroagglutinin were the only highly branched N‐linked residues evidenced in cats, and they were restricted to the syncytium. Unlike results reported on humans, mice and rats on lectin affinity of decidual cells, sialid acids and complex N‐linked oligosaccharides were not demonstrated in cats. Glycosylation of proteins determines many of their final properties, thus becoming essential for the embryo‐maternal dialogue during implantation and placentation. Changes in glycosylation pattern have been related to pathological pregnancies in other species. Hence, the knowledge about glycosylation profile of the normal cat placenta may lead to a better understanding of both normal and pathological reproductive events.     

Effects of Prolonged in vitro Culture and Cryopreservation on Viability,DNA Fragmentation,Chromosome Stability and Ultrastructure of Bovine Cells from Amniotic Fluid and Umbilical Cord

The objective of this work was to study cellular types that did not participated in the gastrulation process, amniotic fluid cells (AFCs) and umbilical cord cells (UCCs), in conditions of long‐term culture and cryopreserved with different solutions. The AFCs and UCCs were used in a comparative study with ear fibroblast cells (EFCs) that were cultured in vitro until 20 cellular passages and cryopreserved in 10% dimethylsulphoxide (DMSO), 5% dimethyl formamide (DMF) and 7% glycerol (Gly) solutions. The cellular viability, ultrastructure, DNA fragmentation and chromosome stability were evaluated to determine the cellular type most resistant. In all cell types, it was possible to evaluate the AFCs until 15 passages and UCCs until 20 passages with different periods of cellular growth to reach the confluence phase. Solutions containing 10% DMSO ensured viability of 90.33 ± 5.58%, 90.56 ± 4.40% and 81.90 ± 3.31%, respectively for EFCs, AFCs and UCCs, being significantly more efficient and with less variation than other cryoprotectant solutions. The AFCs were more sensitive to cryopreservation and presented low viability rate at the passage 20 (17.2 ± 8.87%). There was no change in karyotype and nuclear fragmentation was low in all cellular passages studied. With the scanning electron analysis was possible the characterization of AFCs and UCCs in suspension. The three cellular types of cells presented different shapes and characteristics on the surface. The results demonstrate that bovine AFCs and UCCs can be isolated, cultured in vitro and cryopreserved in 10% DMSO, not causing damage to DNA and chromosomes. The UCCs were more resistant than AFCs in all aspects.     

The occurrence of dictyocaulus arnfieldi in the lungs of horses

Abstract

Extract

The equine lungworm was first reorded in a donkey (Equus asinus) and named Strongylus arnfieldi by Cobbold (1884) Cobbold, T. S. 1884. Veterinarian, 57(349): 4–7. [Cited by Soliman, 1960.] [Google Scholar]. Later it was recognized in the horse by Railliet and placed in the genus Dictyocaulus by Railliet and Henry in 1907. Numerous reports describe its cosmapolitan distribution although the cases de- scribed below appear to be the first published records of it from New Zealand, apart from a Department of Agriculture Report (Anon., 1966 Anon. Animal Research in the New Zealand Department of Agriculture 1964–5 1966 65 65  [Google Scholar]).     

Prevalence and incidence of intramammary infections in lactating dairy goats

AIM: To determine the prevalence of intramammary infection (IMI) of lactating dairy goats between 0 and 4 days postpartum, the prevalence and incidence rate of new IMI at Weeks 2, 14 and 27 of lactation, and the relationship between herd-level prevalence of IMI and bulk tank somatic cell count (BTSCC).

METHODS: Milk samples were collected from 8% of a herd (total 624 does) from 18 dairy goat herds in the Waikato region of New Zealand, for bacteriology and somatic cell count (SCC) determination, from both glands within 4 days of kidding (Week 0) and again at Weeks 2, 14 and 27. Prevalence of IMI was determined at each time point and incidence rate calculated for Weeks 0–2, 2–14, and 14–27. Greenwood and Reed-Frost models were compared for estimation of the transmission parameter for all pathogens, and for Staphylococcus aureus, coagulase negative staphylococci (CNS) and Corynebacterium spp. separately.

RESULTS: Bacteria were isolated from 1,122/4,814 (23.3%) glands, with CNS (13.4%) and Corynebacterium spp. (7.3%) being the most common isolates. Prevalence of any IMI increased with stage of lactation, varied among herds, and increased with age (all p<0.05). Incidence rate was 80, 24 and 7 new IMI/10,000 gland days for Weeks 0–2, 2–14 and 14–27, respectively. Incidence rate for any IMI increased with age and with the presence of an IMI in the contralateral gland, and varied among herds (p<0.001). The transmission of each pathogen was better modelled assuming contagiousness (Reed-Frost models), than not (Greenwood models).

At gland level, IMI increased SCC at all stages of lactation (p<0.001). The gland prevalence of IMI within herds was positively associated with ln BTSCC at Week 2 (p=0.02), but not Weeks 14 or 27 (p>0.05).

CONCLUSIONS: Prevalence of IMI increased with stage of lactation, but the highest incidence rate of new IMI occurred in early lactation. Models accounting for the contagious nature of infection fitted better than those not accounting for contagiousness. BTSCC was only associated with prevalence of IMI in early lactation.

CLINICAL RELEVANCE: Reduction of BTSCC in dairy goats may be best achieved by minimising the prevalence and incidence of new IMI in early lactation. Further studies are required to define management factors associated with the between herd, and stage of lactation, effects on prevalence and incidence rate in order to reduce BTSCC throughout lactation.