Transgenic potato plants resistant to viruses

Summary Traditional potato breeding is a laborious process in which, by intercrossing, valuable traits from different parental clones are combined in a progeny genotype. Depending on the availability of genes, molecular techniques can be used to add specific genes to existing cultivars that, although otherwise satisfactory, lack a lew commercially important traits. For virus resistance the gene for the coat protein of a given virus transplanted into the genome of the plant renders the plant resistant to that virus. In conferring such resistance to potato varieties it proved to be possible to preserve their intrinsic properties.     

Helical superstructures from charged Poly(styrene)-Poly(isocyanodipeptide) block copolymers

Amphiphilic block copolymers containing a poly(styrene) tail and a charged helical poly(isocyanide) headgroup derived from isocyano-L-alanine-L-alanine and isocyano-L-alanine-L-histidine were prepared. Analogous to low-molecular mass surfactants, these block copolymers self-assembled in aqueous systems to form micelles, vesicles, and bilayer aggregates. The morphology of these aggregates can be controlled by variation of the length of the poly(isocyanide) block, the pH, and the anion-headgroup interactions. The chirality of the macromolecules results in the formation of helical superstructures that have a helical sense opposite to that of the constituent block copolymers. The great variety of morphologies displayed by these block copolymers and the fact that they are easily accessible from poly(styrene) and different types of peptides open new opportunities for applications in the fields of life and materials sciences.     

The effect of rotational grazing for periods of one or two weeks on the build‐up of lungworm and gastrointestinal nematode infections in calves

Summary

An experiment was carried out with three groups of grazing calves and one housed control group to study the effect of rotational grazing for periods of 1 and 2 weeks on the build up of lungworm and gastro‐intestinal nematode infections respectively. The experiment demonstrated that rotational grazing for periods of I week on six plots prevented the build‐up of heavy lungworm infections. A buildup of heavier lungworm infections was observed in a group that was rotationally grazed for periods of 2 weeks on three plots and a group which remained on one plot throughout the grazing season; there was no difference between these two groups. In all three situations, there was an adequate development of immunity against D. viviparus, as measured by worm recovery after challenge infection at the end of the experiment in comparison with worm recovery of the similarly challenged control group. Neither rotational grazing scheme protected the calves against gastrointestinal helminthiasis, because tracer calves, which grazed for 4 days only in August or October, acquired infections which would have resulted in severe illness or even death if necropsy had been postponed for a week.     

Gill Infection Model for Columnaris Disease in Common Carp and Rainbow Trout

Challenge models generating gill lesions typical for columnaris disease were developed for the fry of both Common Carp Cyprinus carpio and Rainbow Trout Oncorhynchus mykiss by means of an immersion challenge and Flavobacterium columnare field isolates were characterized regarding virulence. Carp inoculated with highly virulent isolates revealed diffuse, whitish discoloration of the gills affecting all arches, while in trout mostly unilateral focal lesions, which were restricted to the first two gill arches, occurred. Light microscopic examination of the gills of carp exposed to highly virulent isolates revealed a diffuse loss of branchial structures and desquamation and necrosis of gill epithelium with fusion of filaments and lamellae. In severe cases, large parts of the filaments were replaced with necrotic debris entangled with massive clusters of F. columnare bacterial cells enwrapped in an eosinophilic matrix. In trout, histopathologic lesions were similar but less extensive and much more focal, and well delineated from apparently healthy tissue. Scanning and transmission electron microscopic observations of the affected gills showed long, slender bacterial cells contained in an extracellular matrix and in close contact with the destructed gill tissue.

This is the first study to reveal gill lesions typical for columnaris disease at macroscopic, light microscopic, and ultrastructural levels in both Common Carp and Rainbow Trout following a challenge with F. columnare. The results provide a basis for research opportunities to examine pathogen–gill interactions.

Received January 10, 2014; accepted July 27, 2014     

Prevalence of Multi-Drug-Resistant Salmonella in Equids Maintained by Low Income Individuals and on Designated Equine Farms in India

We examined 872 equids (445 maintained by low-income individuals and 427 maintained on nine designated equine farms) and, using previously described methods for bacteria, isolated Salmonella from fecal samples of 59 (6.77%) animals. Of the 646 horses, 183 donkeys, and 43 mules that had feces cultured for Salmonella, 42 (6.5%), 7 (3.8%), and 10 (23.3%), respectively, were excreting Salmonella strains in feces. Six horse mares were excreting Salmonella enterica of two different serovars simultaneously. A total of 65 Salmonella enterica isolates belonged to 13 serovars, namely S. paratyphi B var Java (14), S. I. 4, 5, 12, 27: r, i: 1, 5 (11), S. Drogana (8), S. Newport (7), S. Saintpaul (5), S. Lagos (4), S. Typhimurium (5), S. Kottbus (3), S. Bovismorbificans (3), S. Dumfries (2), S. Tshiongwe (1) S. Weltevreden (monophasic) (1), and S. enterica ssp salamae (1). With Salmonella-specific polymerase chain reaction (PCR) using hisJ gene primers, 107 (12.3) fecal samples yielded a specific amplicon of 496 bp. On using PCR, prevalence of Salmonella in donkeys, horses, and mules was 4.9%, 10.8%, and 65.1%, respectively. With both methods of Salmonella detection in feces, prevalence was significantly higher in female than in male donkeys and horses. Salmonella shedding in feces was significantly higher in equids maintained by low-income people than those at designated equine farms. Almost all Salmonella isolates (63 of 65) had multiple-drug-resistance (MDR, resistance to three or more drugs). Salmonella isolates were commonly resistant to sulfamethoxazole (90.8%), tetracycline (70.8%), doxycycline (67.7%), furazolidone (66.2%), and colistin (55.4%). A few isolates had resistance to trimethoprim (3.1%), ciprofloxacin (3.1%), ceftriaxone (3.1%), ceftazidime (3.1%), cefoperazone (3.1%), chloramphenicol (4.6%), cefotaxime (6.2%), gentamicin (9.2%), ampicillin + cloxacillin (9.2%), cotrimoxazole (13.8%), kanamycin (13.8%), amoxicillin + clavulanic acid (16.9%), imipenem (16.9%), ampicillin (18.5%), amikacin (23.1%), neomycin (27.7%), nalidixic acid (33.8%), and streptomycin (36.9%). With the exception of 13 Salmonella isolates of S. Drogana (4), S. Newport (4), S. I. 4, 5, 12, 27: r, i: 1, 5 (4) and S. Kottbus (1) serovars, all had one or more than one plasmid. Molecular weight of plasmids ranged between 3 kDa and >87 kDa. One heavy plasmid (≥87 kda) was present in all the 52 plasmid-positive strains. Presence of plasmid could not be correlated with MDR in Salmonella isolates from equids.     

Comparison of natural resistance in seven genetic groups of meat-type chicken

1. Several studies have shown that genetic variation exists in response to various Salmonella strains in mammals and poultry. In the current study immunocompetence traits related to natural resistance to Salmonella were measured in 7 genetic groups of meat-type chickens (in total 296 chickens involved). 2. Variables were measured of both innate (phagocytic activity) and adaptive immune responses that are important after a natural or experimental Salmonella enteritidis infection. Two traditional Old Dutch Breeds (groups 1 and 2), four commercial broiler groups (groups 3 to 6), and one experimental broiler group (group 7) were used. In two periods, birds of each group were killed for examination at ages between 14 and 35 d post hatch. 3. Significant differences between groups were found for most immune variables measured, with significant correlations between several of them. All groups produced an adequate immune response, of either the innate or the adaptive type. 4. In the current study, group 2 showed the highest overall natural resistance, though none of the groups was uniformly superior with respect to all traits measured. 5. In conclusion, for reliable measurements of general immunocompetence or resistance to Salmonella, for example, it is important to measure several aspects of the immune system.     

Fertility Results of Artificial Inseminations Performed with Liquid Boar Semen Stored in X-CellTM vs BTS Extender

The objective of the present field study was to compare the fertility results for boar semen diluted in X-cell stored up to 4-5 days before artificial insemination (AI) with semen diluted in Beltsville thawing solution (BTS) used for AI following 2-3 days of storage (where the first day being the collection day). A total number of 2601 double inseminations in Norwegian herds were included in this two-trial study. All the boars used in the study were mature cross-bred Norwegian Landrace x Duroc (LD), which were routinely used for AI in Norway. The inseminated gilts and sows were Norwegian Landrace x Yorkshire (LY). The AI doses contained 2.5 billion spermatozoa, and consisted of a mixture of semen from three, occasionally four, boars (i.e. heterospermic semen). Fertility was measured in terms of the likelihood of farrowing and subsequent litter size. The fertility of the semen in both of the extenders was satisfactory and no significant differences were found either in semen stored 4-5 days in X-cell compared with 2-3 days in BTS or in semen stored 2-3 days in X-cell compared with 2-3 days in BTS. The storage capability findings for the long-term extender X-cell could significantly simplify the practical issues of semen production and the distribution of AI doses containing 2.5 billion spermatozoa. However, in pig production systems where all semen is used within 2-3 days, the short-term extender BTS is as good as the more expensive extender X-cell.