Introduction of allien variation into wheat by gene recombination. I. Crosses between mono V (5B) Triticum aestivum L. and Secale cereale L. and Aegilops columnaris zhuk.

An analysis is made of meiotic pairing of hybrids whether or not deficient in the chromosome V (5B) from crosses between Mono V (5B) T. aestivum var. Chinese Spring and Secale cereale and Aegilops columnaris. Transmission rates of deficiency are not equal for both combinations. Isochromosomes are found in the hybrid plants.5B deficiency allows the pairing and recombination between the chromosomes of wheat and those of the related species. Such deficiency may be a useful wheat breeding tool to introduce alien variation into such cultivated species.Effectiveness of 5B deficiency on meiotic pairing of the hybrids, measured as the increase of the proportion of complement paired, is 36–37% and 49–50% in the hybrids involving rye and Ae. columnaris respectively. Minimum percentages of the introduction of alien variation into wheat are established for the material investigated: 2% for rye and 28% for Ae. columnaris.Methods of utilisation of the 5B deficiency in a programme of wheat breeding are discussed and outlined.     

Magnetic fields at uranus

The magnetic field experiment on the Voyager 2 spacecraft revealed a strong planetary magnetic field of Uranus and an associated magnetosphere and fully developed bipolar masnetic tail. The detached bow shock wave in the solar wind supersonic flow was observed upstream at 23.7 Uranus radii (1 R(U) = 25,600 km) and the magnetopause boundary at 18.0 R(U), near the planet-sun line. A miaximum magnetic field of 413 nanotesla was observed at 4.19 R(U ), just before closest approach. Initial analyses reveal that the planetary magnetic field is well represented by that of a dipole offset from the center of the planet by 0.3 R(U). The angle between Uranus' angular momentum vector and the dipole moment vector has the surprisingly large value of 60 degrees. Thus, in an astrophysical context, the field of Uranus may be described as that of an oblique rotator. The dipole moment of 0.23 gauss R(3)(U), combined with the large spatial offset, leads to minimum and maximum magnetic fields on the surface of the planet of approximately 0.1 and 1.1 gauss, respectively. The rotation period of the magnetic field and hence that of the interior of the planet is estimated to be 17.29+/- 0.10 hours; the magnetotail rotates about the planet-sun line with the same period. Thelarge offset and tilt lead to auroral zones far from the planetary rotation axis poles. The rings and the moons are embedded deep within the magnetosphere, and, because of the large dipole tilt, they will have a profound and diurnally varying influence as absorbers of the trapped radiation belt particles.     

Mutants in the lipopolysaccharide of Brucella ovis are attenuated and protect against B. ovis infection in mice

Brucella spp. are Gram-negative bacteria that behave as facultative intracellular parasites of a variety of mammals. This genus includes smooth (S) and rough (R) species that carry S and R lipopolysaccharides (LPS), respectively. S-LPS is a virulence factor, and mutants affected in the S-LPS O-polysaccharide (R mutants), core oligosaccharide or both show attenuation. However, B. ovis is naturally R and is virulent in sheep. We studied the role of B. ovis LPS in virulence by mutating the orthologues of wadA, wadB and wadC, three genes known to encode LPS core glycosyltransferases in S brucellae. When mapped with antibodies to outer membrane proteins (Omps) and R-LPS, wadB and wadC mutants displayed defects in LPS structure and outer membrane topology but inactivation of wadA had little or no effect. Consistent with these observations, the wadB and wadC but not the wadA mutants were attenuated in mice. When tested as vaccines, the wadB and wadC mutants protected mice against B. ovis challenge. The results demonstrate that the LPS core is a structure essential for survival in vivo not only of S brucellae but also of a naturally R Brucella pathogenic species, and they confirm our previous hypothesis that the Brucella LPS core is a target for vaccine development. Since vaccine B. melitensis Rev 1 is S and thus interferes in serological testing for S brucellae, wadB mutant represents a candidate vaccine to be evaluated against B. ovis infection of sheep suitable for areas free of B. melitensis.     

Antibacterial susceptibility patterns of Pseudomonas strains isolated from chronic canine otitis externa

Development of antibiotic resistance in bacteria is a problem of great concern. It is important to establish the convenience of antimicrobial susceptibility tests in animal infections. The aim of this study was to test the susceptibility to antibiotics of Pseudomonas strains isolated from chronic canine otitis externa. We tested 23 strains of Pseudomonas: 19 Ps. aeruginosa, three Ps. fluorescens and one Pseudomonas spp. The most effective antibiotics were tobramycin (100% susceptible), marbofloxacin (91.3%) and ceftazidime (91.3%). Ticarcillin and gentamicin, commonly used for the treatment of otitis externa also showed good results (susceptibility of strains was 86 and 65.2% respectively). Lower susceptibility was found using enrofloxacin (52.1%) probably due to its indiscriminate use. We emphasize the need for a rational policy of antibiotic prescribing in order to prevent the selection of resistant strains.     

Intravaginal progesterone devices in synchronization protocols for artificial insemination in beef heifers

Two experiments were designed to investigate the administration of intravaginal progesterone in protocols for oestrus and ovulation synchronization in beef heifers. In Experiment 1, cyclic Black Angus heifers (n = 20) received an Ovsynch protocol and were randomly assigned to receive (CIDR‐Ovsynch) or not (Ovsynch) a progesterone device between Days 0 and 7. Treatment with a controlled internal drug release (CIDR) device significantly increased the size of the dominant follicle prior to ovulation (12.8 ± 0.4 CIDR‐Ovsynch vs 11.4 ± 0.4 Ovsynch) (p < 0.02). Plasma progesterone concentrations throughout the experiment were affected by the interaction between group and day effects (p < 0.004). In Experiment 2, cyclic Polled Hereford heifers (n = 382) were randomly assigned to one of the six treatment groups (3 × 2 factorial design) to receive a CIDR, a used bovine intravaginal device (DIB), or a medroxiprogesterone acetate (MAP) sponge and GnRH analogues (lecirelin or buserelin). All heifers received oestradiol benzoate plus one of the devices on Day 0 and PGF on Day 7 pm (device withdrawal). Heifers were detected in oestrus 36 h after PGF and inseminated 8–12 h later, while the remainder received GnRH 48 h after PGF and were inseminated on Day 10 (60 h). The number of heifers detected in oestrus on Day 8 and conception rate to AI on Day 9 were higher (p < 0.01) in the used‐DIB than in the CIDR or MAP groups, while the opposite occurred with the pregnancy rate to FTAI on Day 10 (p < 0.01). There was no effect of progesterone source, GnRH analogue or their interaction on overall pregnancy rates (64.9%). Progesterone treatment of heifers during an Ovsynch protocol resulted in a larger pre‐ovulatory follicle in beef heifers. Progesterone content of intravaginal devices in synchronization protocols is important for the timing of AI, as the use of low‐progesterone devices can shorten the interval to oestrus.     

Upregulation of LENK and VIP in paracervical ganglion neurons supplying the urinary bladder of tetrodotoxin- and resiniferatoxin-treated female pigs

Both resiniferatoxin (RTX) and tetrodotoxin (TTX) have been reported to be effective in several clinical trials aiming to cure urinary bladder dysfunction. The goal of this experiment was to study the effect of intravesical administration of RTX and TTX on the chemical coding of paracervical ganglion (PCG) neurons that supply the urinary bladder in pigs. The vasoactive intestinal peptide (VIP) and the opioid family member Leu5-enkephalin (LENK) are both known for their regulatory effects in the function of the porcine genitourinary tract. The PCG neurons innervating the urinary bladder were identified by application of the retrograde tracer Fast Blue (FB), injected into the bladder wall prior to intravesical RTX or TTX administration. Immunocytochemical detection of LENK and VIP expression in the FB-labelled perikarya revealed that in the control group 25.15% of the FB-positive PCG neurons contained LENK, and 9.22% of them expressed VIP. Intravesical infusion of RTX resulted in an increase in the number of LENKIR neurons to 48.19% and VIP-IR perikarya to 11.25%. Optional treatment with TTX induced increase of LENK-IR neurons up to 81.67% and VIP-IR population to 16.46% of the FB-positive PCG cells. The present results show that both neurotoxins affect the chemical coding of PCG nervous cells supplying the porcine urinary bladder and that they stimulate both LENK and VIP expression. Furthermore, the results indicate a possible involvement of LENK and VIP neurons in the mechanisms of action of RTX and TTX in the therapy of overactive bladder disorder.     

Fusobacteriosis in captive wild-caught pronghorns (Antilocapra americana)

An outbreak of Fusobacterium necrophorum-induced septicemia occurred in a group of 40 captive wild-caught pronghorns (Antilocapra americana). Primary pododermatitis or necrotic stomatitis progressed to produce fatal septicemia with metastatic lesions in the forestomachs, lung, liver, and cecum in 38 of the animals. Two remaining animals were euthanatized because of chronic pododermatitis. Housing the animals in a pasture previously used by bovids and heavy rains with persistence of ground water pools in the pasture were contributing factors in the pathogenesis of this outbreak.     

Hybridization and invasive species in a threatened freshwater fish community under environmental pressures: Morphometric and molecular evidence

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