Towards F<Subscript>1</Subscript> Hybrid Seed Potato Breeding

Compared to other major food crops, progress in potato yield as the result of breeding efforts is very slow. Genetic gains cannot be fixed in potato due to obligatory out-breeding. Overcoming inbreeding depression using diploid self-compatible clones should enable to replace the current method of out-breeding and clonal propagation into an F₁ hybrid system with true seeds. This idea is not new, but has long been considered unrealistic. Severe inbreeding depression and self-incompatibility in diploid germplasm have hitherto blocked the development of inbred lines. Back-crossing with a homozygous progenitor with the Sli gene which inhibits gametophytic self-incompatibility gave self-compatible offspring from elite material from our diploid breeding programme. We demonstrate that homozygous fixation of donor alleles is possible, with simultaneous improvement of tuber shape and tuber size grading of the recipient inbred line. These results provide proof of principle for F₁ hybrid potato breeding. The technical and economic perspectives are unprecedented as these will enable the development of new products with combinations of useful traits for all stakeholders in the potato chain. In addition, the hybrid’s seeds are produced by crossings, rendering the production and voluminous transport of potato seed tubers redundant as it can be replaced by direct sowing or the use of healthy mini-tubers, raised in greenhouses.     

The Possible Involvement of Salsolinol and Hypothalamic Prolactin in the Central Regulatory Processes in Ewes During Lactation

Salsolinol, a dopamine‐related compound and prolactin‐producing cells were found in the ovine hypothalamus. This study was designed to test the hypothesis that salsolinol, acting from the CNS level, is able to stimulate pituitary prolactin release as well as prolactin mRNA expression in the anterior pituitary cells (AP) and in the mediobasal hypothalamus (MBH) in lactating ewes. The intracerebroventricular infusions of salsolinol in two doses, total of 50 ng or 5 μg, were performed in a series of five 10‐min infusions at 20‐min intervals. All infusions were made from 12:30 to 15:00 and the pre‐infusion period was from 10:00 to 12.30 h. The prolactin concentration in plasma samples, collected every 10 min, was determined by radioimmunoassay; prolactin mRNA expression in AP and MBH tissues was determined by real‐time PCR. The obtained results showed that salsolinol infused at the higher dose significantly (p < 0.001) increased plasma prolactin concentration in lactating ewes, when compared with the concentration noted before the infusion and with that in lactating controls. In lactating ewes, the relative levels of prolactin mRNA expression in the AP and MBH were up to twofold and fivefold higher respectively than in non‐lactating ewes (p < 0.05). In our experimental design, salsolinol did not significantly affect the ongoing process of prolactin gene expression in these tissues. We conclude that in ewes, salsolinol may be involved, at least, in the process of stimulation of prolactin release during lactation and that hypothalamic prolactin plays an important role in the central mechanisms of adaptation to lactation.     

Alphaherpesvirus use and misuse of cellular actin and cholesterol

Two major structural elements of a cell are the cytoskeleton and the lipid membranes. Actin and cholesterol are key components of the cytoskeleton and membranes, respectively, and are involved in a plethora of different cellular processes. This review summarizes and discusses the interaction of alphaherpesviruses with actin and cholesterol during different stages of the replication cycle: virus entry, replication and assembly in the nucleus, and virus egress. Elucidating these interactions not only yields novel insights into the biology of these important pathogens, but may also shed new light on cell biological aspects of actin and cholesterol, and lead to novel avenues in the design of antiviral strategies.     

The Influence of a Particle Separation Technology on the Generation of Airborne Particles from Different Roughages and Bedding Materials Used for Horses

Four different types of bedding materials (wheat straw, wood shavings, hemp shives, flax shives) and two roughages (hay, haylage) were treated using an air-driven particle separation technology. The airborne particle and mold generation of both treated and untreated samples were then analyzed under standardized laboratory conditions. In addition, samples of all the treated materials were stored for 8 weeks either in a pressed or incoherent form and then analyzed again for their ability to generate airborne particles. The airborne particle concentrations were detected online with the gravimetrically measuring analyzer tapered element oscillating microbalance (TEOM) 1400a that was equipped successively with different inlets to measure the particle fractions PM₂₀, PM₁₀, PM_2.5, and PM_1.0 (PM = Particulate matter). The particle separation resulted in a reduction in the airborne particle (PM₂₀) generation in all materials: hay 49.16 to 22.79 mg/m³ (53.6%), haylage 28.57 to 25.04 mg/m³ (12.3%), wood shavings 141.68 to 15.04 mg/m³ (89.4%), wheat straw 143.08 to 22.97 mg/m³ (83.9%), flax 135.11 to 53.31 mg/m³ (60.5%), and hemp 63.67 to 17.64 mg/m³ (72.3%). The 8-week storage of the treated materials as compressed materials led to a renewed significant increase in the airborne particle (PM₁₀) concentration in the haylage (+29.9%), wheat straw (+104.0%), wood shavings (+40.4%), and hemp shives (+30.7%). Storage of the incoherent materials caused a significant increase in these particles only in the wheat straw (+44.2%). The separation treatment reduced the mold production by 92.4% in the wood shavings, 88.0% in the wheat straw, and 85.8% in the hay.     

Land-cover change and human population trends in the greater Serengeti ecosystem from 1984–2003

The growth of human populations around protected areas accelerates land conversion and isolation, negatively impacting biodiversity and ecosystem function, and can be exacerbated by immigration. It is often assumed that immigration around protected areas is driven by attraction in the form of economic benefits, but in many cases, people may be pushed from their areas of origin toward protected areas. Mitigating the effects of immigration around protected areas necessitates understanding the actual mechanisms causing it, which can be aided by analysis of patterns of land-cover change. Our goal was to identify the reasons for human population growth and land-cover change around the protected areas in the greater Serengeti ecosystem (henceforth “the park”), and to relate agricultural conversion from 1984–2003 to trends in human demography. We found that conversion of natural habitats to agriculture was greatest closer to the park (up to 2.3% per year), coinciding with the highest rates of human population growth (3.5% per year). Agricultural conversion and population growth were greatest where there was less existing agriculture, and population density was lowest. Lack of unfarmed land farther from the park, coupled with greater poverty near the park, suggest that movement away from areas with high population densities and land scarcity was likely driving immigration near the park, where arable land was available. Our results are essential for conservation planning for one of Africa’s hallmark ecosystems, and should encourage further examination of population growth and land-cover trends near protected areas throughout the developing world.     

Temporary Turnout for Free Exercise in Groups: Effects on the Behavior of Competition Horses Housed in Single Stalls

In Germany, most competition horses are housed in single stalls and free exercise is not permitted in many cases. The reason for not allowing free exercise is mostly the risk of injury. Additionally, opinions exist that the horses’ demand for exercise is fulfilled by training and that the horses’ willingness to perform is negatively influenced by free exercise. In the present study, three turnout practices were investigated with regard to their effect on the behavior of four horses: daily training without free exercise (no turnout), 2-hour turnout (for free exercise) before training, and 2-hour turnout after training. The aim of this study was to determine any differences in the horses’ behavior between the three treatments. The horses’ behavior in the stable was observed through video recordings. The behavior during turnout was observed directly and during training was evaluated by the riders with the aid of a questionnaire. Additionally, the distance covered during turnout was measured by Global Positioning System devices. The behavior within the stall was more restless in the treatment without turnout—which became apparent in significantly more frequent changes between behaviors as compared with the treatments with turnout. The results of Global Positioning System measurement during turnout showed a significantly shorter distance covered when horses were trained before they were turned out compared with turnout before training. If the horses were turned out after training, they also showed less trotting and cantering and more dozing. The horses’ willingness to perform was not significantly different between the three treatments.     

Breeding with resistant rams leads to rapid control of classical scrapie in affected sheep flocks

ABSTRACT: Susceptibility to scrapie, a transmissible spongiform encephalopathy in sheep, is modulated by the genetic make-up of the sheep. Scrapie control policies, based on selecting animals of resistant genotype for breeding, have recently been adopted by the Netherlands and other European countries. Here we assess the effectiveness of a breeding programme based on selecting rams of resistant genotype to obtain outbreak control in classical scrapie-affected sheep flocks under field conditions. In six commercially-run flocks following this breeding strategy, we used genotyping to monitor the genotype distribution, and tonsil biopsies and post-mortem analyses to monitor the occurrence of scrapie infection. The farmers were not informed about the monitoring results until the end of the study period of six years. We used a mathematical model of scrapie transmission to analyze the monitoring data and found that where the breeding scheme was consistently applied, outbreak control was obtained after at most four years. Our results also show that classical scrapie control can be obtained before the frequency of non-resistant animals is reduced to zero in the flock. This suggests that control at the national scale can be obtained without a loss of genetic polymorphisms from any of the sheep breeds.     

Validating the assessment of bull sperm morphology by veterinary practitioners

The objective of this study was to validate the assessment of bull sperm morphology done by veterinary practitioners. Out of 1606 bulls, 1400 (87.2%) and 1344 (83.7%) were designated by practitioners and an experienced andrologist, respectively, as having > 70% morphologically normal sperm. In 92% of the evaluations, there was agreement between the designations chosen.