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Mammalian ribonucleases. The absence of a glycosylated Asn-Pro-Thr sequence in horse ribonuclease and the presence of tryptophan at position 39 in horse and dromedary ribonuclease.

Parts of the amino acid sequences of horse and dromedary pancreatic ribonuclease were reinvestigated. The sequence of residues 21-25 in horse ribonuclease is Ser-Asn-Pro-Thr-Tyr or Ser-Asn-Ser-Thr-Tyr. The asparagine in the latter sequence is glycosylated. Horse ribonuclease possesses four additional amino acid residues at the C-terminus, like a number of other ribonucleases. Position 39 in horse and dromedary ribonuclease is not deleted but is occupied by tryptophan.

Amino Acid Sequence↗

[Horse breeding: genetic tests for the coat colors chestnut, bay and black. Results from a preliminary study in the Swiss Freiberger horse breed].

Coat color played an important role during domestication and formation of breeds. Livestock breeders often had special preferences for particular color phenotypes because they believed them to be associated with performance or fitness traits. Socio-cultural reasons might have had an influence on color selection as well. Recently genetic tests on DNA level got available to genotype in any individual horse for basic horse coat colors (chestnut, bay, black). In particular, hidden carriers of the recessive chestnut and black allele are recognizable with these tests. A sample of 162 Franches-Montagnes horses from Switzerland was genotyped for the alleles for chestnut and black. The analysis of allele frequencies revealed a high prevalence of the chestnut allele and a low frequency of the black allele in this population. Rare colors are in demand on the market. The statistical analysis of 1369 offspring from five stallions indicate, that darker shades of basic color phenotypes (dark chestnut, dark bay) follow a recessive mode of inheritance in the Franches-Montagnes horse breed.

Animals↗

Patterns of intracellular calcium oscillations in horse oocytes fertilized by intracytoplasmic sperm injection: possible explanations for the low success of this assisted reproduction technique in the horse.

In all species studied, fertilization induces intracellular Ca2+ ([Ca2+]i) oscillations required for oocyte activation and embryonic development. This species-specific pattern has not been studied in the equine, partly due to the difficulties linked to in vitro fertilization in this species. Therefore, the objective of this study was to use intracytoplasmic sperm injection (ICSI) to investigate fertilization-induced [Ca2+]i signaling and, possibly, ascertain problems linked to the success of this technology in the horse. In vivo- and in vitro-matured mare oocytes were injected with a single motile stallion sperm. Few oocytes displayed [Ca2+]i responses regardless of oocyte source and we hypothesized that this may result from insufficient release of the sperm-borne active molecule (sperm factor) into the oocyte. However, permeabilization of sperm membranes with Triton-X or by sonication did not alleviate the deficient [Ca2+]i responses in mare oocytes. Thus, we hypothesized that a step downstream of release, possibly required for sperm factor function, is not appropriately accomplished in horse oocytes. To test this, ICSI-fertilized horse oocytes were fused to unfertilized mouse oocytes, which are known to respond with [Ca2+]i oscillations to injection of stallion sperm, and [Ca2+]i monitoring was performed. Such pairs consistently displayed [Ca2+]i responses demonstrating that the sperm factor is appropriately released into the ooplasm of horse oocytes, but that these are unable to activate and/or provide the appropriate substrate that is required for the sperm factor delivered by ICSI to initiate oscillations. These findings may have implications to improve the success of ICSI in the equine and other livestock species.

Animals↗

Saving feral horse populations: does it really matter? A case study of wild horses from Doñana National Park in southern Spain.

In the 1980s, a conservation programme involving a feral horse population, the Retuertas horses from the Guadalquivir marshes, was started in the Doñana National Park. The analysis of an extensive genetic survey of this population, which now numbers 100 animals, and 10 additional European and North African breeds using DNA polymorphisms from 22 microsatellites is presented. Highly significant fixation indexes were obtained for all pairwise comparisons between the Retuertas population and other breeds. A population neighbour-joining breed phenogram was built using different distance measures, but the Retuertas population failed to cluster with either of the two major clades of European and North African breeds, highlighting its uniqueness. In fact, the Retuertas population was positioned at the base of the trees, which were rooted using donkey samples. Furthermore, assignment tests and the individual Q-matrices obtained with the structure programme isolated the Retuertas breed from the other breeds with only four K groups. Interestingly, some local semi-feral horses, known as Marismeño, also currently living in the Guadalquivir marshes, have some microsatellite genotypes that fall well within the Retuertas cluster. This raises the possibility of incorporating horses from the Marismeño population in a future conservation programme.

Albumins↗

Stromal cells from human long-term marrow cultures, but not cultured marrow fibroblasts, phagocytose horse serum constituents: studies with a monoclonal antibody that reacts with a species-specific epitope common to multiple horse serum proteins.

This report describes an IgG1 mouse monoclonal antibody derived after immunization of mice with washed stromal cells from human, long-term bone marrow cultures. The antigen recognized by the antibody (BMS-1) is a carbohydrate-containing prosthetic group that is common to and specific for multiple horse serum proteins. These proteins are avidly ingested by stromal cells and concentrated in endocytic vesicles. Cultured smooth muscle cells took up the horse proteins in a similar manner to marrow stromal cells while cultured marrow fibroblasts, endothelial cells, and hepatoma cells did not. These data indicate that marrow stromal cells specifically accumulate horse serum proteins which might partially explain the horse serum requirement for long-term marrow culture maintenance. The data also suggest further similarities between marrow stromal and smooth muscle cells and additional differences between marrow fibroblasts and marrow stromal cells.

Animals↗

Residues of diflubenzuron on horse chestnut (Aesculus hippocastanum) leaves and their efficacy against the horse chestnut leafminer, Cameraria ohridella.

Residues of the insect growth regulator diflubenzuron were quantified on horse chestnut (Aesculus hippocastanum L.) leaves treated with a diflubenzuron 480 g litre(-1) SC, Dimilin. To analyse the samples, an analytical procedure was developed involving a simple extraction step followed by high-performance liquid chromatography on an octadecyl-modified silica column with methanol + 0.01 M ammonium acetate mobile phase. The results showed diflubenzuron to be highly stable on horse chestnut leaves; more than 4 months (127 days) after application, 38% (on average) of the insecticide still remained on/in the leaves. The data confirmed biological observations showing diflubenzuron's long-term efficacy against the horse chestnut leafminer, Cameraria ohridella Deschka and Dimić, which is the most important pest of the horse chestnut in Europe. The hypothesis of possible penetration of diflubenzuron into the leaf mass is explored and discussed.

Aesculus↗

The use of African horse sickness virus NS3 protein, expressed in bacteria, as a marker to differentiate infected from vaccinated horses.

Segment 10 of the double-stranded RNA (dsRNA) genome from African horse sickness virus serotype 4 (AHSV-4) was cloned and sequenced. The sequence of the coding region showed a total length of 667 bp. Nucleotide comparisons showed a 95% sequence similarity between serotypes 4 and 9, and 76% between serotypes 4 and 3. cDNA clones containing the coding region were cloned in the vector pET3xb and expressed in Escherichia coli. The NS3 gene product was synthesised at very high level as an insoluble fusion protein. The recombinant protein was used in a differential ELISA to distinguish horses that were infected with AHSV-4 or vaccinated with live-modified virus from those vaccinated with a purified inactivated vaccine. The results obtained indicate that recombinant NS3 can indeed differentiate between infected and vaccinated animals implying that this recombinant could be developed as a diagnostic reagent, and it would allow the mobility of vaccinated horses. Thus, economical losses associated with this disease could be avoided.

African Horse Sickness↗

Ivermectin treatment of horses: effect on the distribution of lawns and roughs in horse pastures.

A study was carried out to assess the feasibility of determining the grazing patterns of horses bimonthly via aerial survey and standard cartographic techniques. The grazing patterns in pastures with equivalent stocking rates of horses treated bimonthly with 200 micrograms of ivermectin kg-1 or 10 mg of oxibendazole kg-1 was assessed using aerial survey mapping performed three times during a grazing season. The distribution patterns of lawns and roughs in pastures were similar at all times during the study. Aerial survey was determined to be a very efficient and objective method of determining the composition of pastures grazed by horses.

Animals↗

EGF receptor-binding activity in the urine of normal horses and horses affected by chronic laminitis.

A heterologous radioreceptor binding assay (RRA) has been developed capable of detecting nanogram amounts of epidermal growth factor (EGF) receptor-binding activity in equine urine. The binding parameters of [125I]mEGF (murine EGF) to EGF receptors on equine plasma membranes are in good agreement with values from other EGF-RRA systems. The dissociation constant estimated from equilibrium methods (KD = 4 X 10(-10) M) is in reasonable agreement with that determined from the rate constants (KD = 6 X 10(-10) M) and is in good agreement with values determined in other species. The assay is specific for equine EGF (eEGF) receptor-binding activity and capable of detecting less than 0.34 nM eEGF receptor-binding activity in urine. Equine EGF receptor-binding activity in equine urine form adult horses varied widely between samples (8.5 +/- 6.5 nM). This variability was somewhat reduced when values were adjusted for dilutional effects using urine creatinine as an indicator (3.6 +/- 2.0 nanomoles/g creatinine). No significant differences were demonstrated between the means of EGF binding activity concentrations in clinically normal horses and horses affected by chronic laminitis.

Animals↗

Diversity of 16S rRNA genes of new Ehrlichia strains isolated from horses with clinical signs of Potomac horse fever.

Ehrlichia risticii is the causative agent of Potomac horse fever. Variations among the major antigens of different local E. risticii strains have been detected previously. To further assess genetic variability in this species or species complex, the sequences of the 16S rRNA genes of several isolates obtained from sick horses diagnosed as having Potomac horse fever were determined. The sequences of six isolates obtained from Ohio and three isolates obtained from Kentucky were amplified by PCR. Three groups of sequences were identified. The sequences of five of the Ohio isolates were identical to the sequence of the type strain of E. risticii, the Illinois strain. The sequence of one Ohio isolate, isolate 081, was unique; this sequence differed in 10 nucleotides from the sequence of the type strain (level of similarity, 99.3%). The sequences of the three Kentucky isolates were identical to each other, but differed by five bases from the sequence of the type strain (level of similarity, 99.6%). The levels of sequence similarity of isolate 081, the Kentucky isolates, and the type strain to the next most closely related Ehrlichia sp., Ehrlichia sennetsu, were 99.3, 99.2, and 99.2%, respectively. On the basis of the distinct antigenic profiles and the levels of 16S rRNA sequence divergence, isolate 081 is as divergent from the type strain of E. risticii as E. sennetsu is. Therefore, we suggest that strain 081 and the Kentucky isolates may represent two new distinct Ehrlichia species.

Animals↗

Ultrasonography of the femoral artery in six normal horses and three horses with thrombosis.

Ultrasonography of the femoral artery in the horse, including color, power and spectral Doppler, provides morphologic and dynamic information. This paper describes the use of the techniques in six clinically normal horses and three with femoral artery thrombosis. Useful landmarks for orientation are the saphenous artery and the medial saphenous vein. The lateral circumflex femoral artery can not be visualized. Recognition of the genus descendens artery is complicated due to the presence of multiple distal caudal femoral arteries. The femoral artery feeds a high resistance bed. In normal horses the peak systolic velocity varies between 50-90 cm/sec. Echoic tissue in the femoral artery lumen with stenosis, occlusion and collateral blood flow formation are features encountered in the patients.

Animals↗

Pulmonary artery pressures in normal horses and in horses affected with chronic obstructive pulmonary disease.

Horses clinically affected with chronic obstructive pulmonary disease (COPD) were found to have pulmonary artery hypertension which was associated with systemic arterial hypoxia. The pulmonary hypertension in symptomatic COPD-affected horses was partially reversible upon remission of clinical signs or by oxygen administration. The induction of acute hypoxaemia caused an increase in pulmonary artery pressure in both normal and COPD-affected horses.

Animals↗

Assessment of myocardial function in the horse. 2. Experimental findings in resting horses.

The paper describes observations on 8 horses at rest using catheter-mounted microtransducers to record intracavity pressures. In 5 of them records were obtained from both left and right sides and in 3 horses from the right heart only. Twelve indices were measured. Variations in left ventricular end-diastolic pressure seemed to influence the results on many of the parameters. It is suggested that left ventricular end-diastolic pressure itself may be a useful guide to left ventricular functional efficiency but more work is necessary to further evaluate these indices as possible measures of myocardial function in the horse.

Animals↗

Characterisation and distribution of epidermal growth factor receptors in equine hoof wall laminar tissue: comparison of normal horses and horses affected with chronic laminitis.

Epidermal growth factor (EGF) receptors were detected in plasma membrane preparations of equine hoof wall laminar tissue at concentrations comparable to that of equine liver. Scatchard analysis of the equilibrium binding data suggested the presence of two classes of EGF binding sites in most of the controls (plasma membranes from clinically normal horses); a high-affinity class and a more numerous low-affinity class. The dissociation constant of the low-affinity class of EGF-specific receptors (KD = 1 x 10(-9)M) is in reasonable agreement with other values established for the EGF receptor. The variability between individual estimates for the KD of the high-affinity receptor class precluded an accurate estimate for those sites. A possible explanation is discussed. The high-affinity binding sites were uniformly absent in plasma membranes prepared from horses affected by chronic laminitis. Autoradiographic analysis localised the EGF receptors primarily to the secondary epidermal laminae, with an apparent greater density over the proliferative basal keratinocytes. Little label was associated with the dermal or the keratinised primary epidermal laminae. Tissue from horses with chronic laminitis had EGF receptors located uniformly over the hyperplastic epidermal keratinocytes. These data suggest that an EGF-mediated response may be involved in the hyperproliferative response that is characteristic of chronic laminitis.

Animals↗

[Detection of Emericella nidulans from bedding materials in horse breeding environment and its significance as a causative agent of guttural pouch mycosis in horses].

Sixty-six new and used samples of horse bedding materials: 60 rice straws, 2 wheat straws, 2 timothy hays and 2 wood chips, were collected from horse breeding stables of 33 farms in Japan and examined for the presence of Emericella nidulans (E. nidulans; anam. Aspergillus nidulans). The incidence of E. nidulans in the bedding materials was 75.8% and there was no significant difference in detection of the fungus between the new and used materials (25 out of the 33 samples, respectively). The growth of E. nidulans isolated in sterilized rice straw culture was accelerated by the addition of water up to about Aw 0.94, which as determined to be the most favorable moisture content. The addition of 0.3% urea solution onto the sterilized rice straw culture also appeared to very effectively enhance its conidial and ascocarp formation. A significant influence of urea on conidial and ascocarp formation of E. nidulans isolates was confirmed by their cultures on a synthetic medium which had urea as the sole nitrogen. These results suggest that severe contamination of E. nidulans on new bedding materials can be hazardous and its proliferation can readily occur at the stable due to the enhancing effect of urine. This analysis is meaningful to elucidate a reservoir of E. nidulans as the causative agent of guttural pouch mycosis in horses.

Animal Husbandry↗

Serially determined plasma alpha-tocopherol concentrations and results of the oral vitamin E absorption test in clinically normal horses and in horses with degenerative myeloencephalopathy.

Plasma alpha-tocopherol (vitamin E) values were monitored serially in 9 foals sired by a stallion with equine degenerative myeloencephalopathy (EDM) and in 5 age-matched control foals (sired by a clinically normal stallion) raised in the same environment for the first year of life. Clinical evaluation determined that 8 of the 9 foals sired by the stallion with EDM had neurologic deficits consistent with the disease on one or more occasions during the study period, whereas control foals had normal gait. From 6 weeks to 10 months of age, plasma alpha-tocopherol values in foals with signs of EDM were significantly (P less than 0.001) lower than those in control foals. An oral vitamin E absorption test was performed, and results for 8 of the affected horses and the affected stallion were compared with results for 4 of the monitored control horses and 4 additional control horses. Significant differences were not evident in any of the absorption indices. On the basis of data from this study and supported by reported prophylactic and therapeutic benefits of supplemented vitamin E, low plasma concentration of vitamin E is concluded to be a factor in the development of EDM in the first year of life of hereditarily predisposed foals. It was also concluded that the significantly lower alpha-tocopherol values seen in the foals in this study did not reflect a primary gastrointestinal tract absorption problem.

Absorption↗

Use of a liquid diet as the sole source of nutrition in six dysphagic horses and as a dietary supplement in seven hypophagic horses.

Six horses with dysphagia (attributable to botulism, glossitis, or guttural pouch mycosis) were given a commercially available liquid diet as the sole source of nutrition. Seven horses with hypophagia caused by severe bacterial pleuropneumonia or peritonitis were given the liquid diet to supplement food consumed voluntarily. The liquid diet was administered through a nasogastric tube 2 or 3 times daily. Body weight did not change significantly, and pertinent laboratory values remained at satisfactory concentrations throughout the feeding period. Serious complications were not encountered. Three horses developed loose, low-volume feces, but did not require treatment.

Animals↗

A growth-promoting factor for human myeloid leukemia cells from horse serum identified as horse serum transferrin.

A growth-promoting factor for human myeloid cells was purified to apparent homogeneity from horse serum by a combination of gel filtration, blue Sepharose affinity chromatography, Mono Q anion-exchange chromatography, Mono P chromatofocusing and sodium dodecyl sulfate polyacrylamide gel electrophoresis. The growth promoter was an iron-bound, single glycopolypeptide chain with a molecular weight of 84,000, an isoelectric point of 5.4 and an amino terminal sequence of Glu-Gln-Thr-Val-Arg-Trp-Cys-Thr-Val-Ser-Asn-His-Glu-Val-Ser-Lys-. According to the results of the amino acid sequence, iron binding ability and physicochemical properties, we identified the growth-promoting factor as horse serum transferrin. It was highly active in promoting the proliferation of a human monocytic leukemia cell line, THP-1, as well as of two other human myeloid cell lines, HL-60 and K-562. It had the same activity in proliferating THP-1 cells as 5% fetal calf serum-supplemented medium. Horse serum transferrin could be substituted for human or bovine serum transferrin.

Amino Acid Sequence↗