Impact of the potato inoculation date on potato virus Y load and viral distribution in daughter tubers at harvest

Aged plants are more difficult to infect than young plantlets. This modification of susceptibility is described as mature plant resistance (MPR). For potato virus Y (PVY), MPR is known to lead to low infection rates of plants inoculated at the postflowering stage and a decrease in the number of infected daughter tubers. However, the impact of inoculation date on the capacity of PVY to accumulate in daughter tubers has not been studied so far. Field and greenhouse experiments were carried out to better understand PVY epidemiology and to help potato growers to evaluate consequences of early/late infections on the quality of their crops. In field trials, potato plants (cv. Bintje) were covered by insectproof nets from planting to harvest except for a 14-day period to expose plants to natural PVY infections. Under controlled conditions, potato plants were mechanically inoculated with PVY at different dates from preflowering stages (early inoculations) to postflowering stage (late inoculations). At harvest, daughter tubers were individually collected and analysed to define proportions and viral load of infected tubers according to the time between virus inoculation and harvest. Our results showed that although the age of plants at the time of inoculation can modify their susceptibility to PVY infection, in return, early and late PVY inoculations lead to similar rates of infected tubers at the plant scale and equivalent viral accumulation in infected tubers. All together, these data revealed that both early/late infections are high risks for the sanitary quality of potato tubers.     

Analytical validation of a portable human Accu-Chek glucometer in honeybee hemolymph

Glucose and trehalose are the main energy sources used by honeybees (Apis mellifera) for daily activities. However, there is no validated point-of-care method to reliably measure both sugars. We performed an analytical validation of a portable human glucometer (Accu-Chek; Roche) for glucose measurement in honeybee hemolymph compared to a reference method (GluCH, UniCel DxC 600; Beckman Coulter). We used 30 pooled hemolymph samples collected from the antennae of anesthetized honeybees and diluted 1:4 in 0.9% saline. We evaluated dilution linearity, spike recovery, and inter- and intra-assay imprecision. Glucose concentration was measured over time (2 h, 4 h, 8 h, 12 h, 1 d, 2 d, 3 d, 7 d, 21 d, 28 d) at various storage temperature (25°C, 4°C, −20°C, −80°C). The trehalose concentration was measured indirectly by trehalase hydrolyzation. Glucose concentrations measured by both instruments had a strong correlation (0.985, p < 0.0001) and a bias of −7.33 mmol/L (±1.96SD: 13.70 to −28.36), with linear agreement at <20 mmol/L (physiologic value: 100 mmol/L). The accuracy of the glucometer decreased at >20 mmol/L. Recovery of 115–130% of diluted spikes indicated good specificity. Inter- and intra-assay imprecision were 2.50% and 2.21%, respectively. Glucose concentrations fluctuated in stored samples dependent on time and temperature; however, glucose concentrations were constant with storage at −80°C for ≥28 d. The Accu-Chek glucometer is an adequate instrument to measure honeybee glucose concentration in hemolymph diluted with 0.9% NaCl, with good accuracy and precision at <20 mmol/L. Hemolymph storage at −80°C is suitable for long-term conservation of glucose.     

Implementation of two high through-put techniques in a novel application: detecting point mutations in large EMS mutated plant populations

Background  

The establishment of mutant populations together with the strategies for targeted mutation detection has been applied successfully to a large number of organisms including many species in the plant kingdom. Considerable efforts have been invested into research on tomato as a model for berry-fruit plants. With the progress of the tomato sequencing project, reverse genetics becomes an obvious and achievable goal.     

Starch granule size variation and relationship with tuber dry matter content in heritage potato varieties

Heritage potato varieties in Canada are historic old varieties collected from Canada and various countries before the formal establishment of the Canadian plant variety registration system and may be a valuable gene resource for beneficial traits in potato breeding and bioproducts development. Greater evaluation is the key for the enhanced use of these materials. It is unknown how much variation of starch granules occurs among Canadian heritage potato varieties. We analyzed the starch granule size of 14 potato heritage varieties held in the Canadian Plant Gene Resources collection over 2 years using a squeezed juice and microscopic method recently developed at the Potato Research Centre. The varieties demonstrated considerable variation in starch granule size and shape. The granules showed average lengths ranging from 18 μm in the variety Congo to 32 μm in ‘Russet Burbank’. The largest single granule measured from 64 μm in ‘Congo’ to 91 μm in ‘Crotte d’Ours.’ The granule sizes of the varieties showed a very high correlation (r = 0.975, P < 0.0001) between years. This high reproducibility suggests the existence of genetic factors in determining starch granule size. We also found that the starch granule size is positively correlated with tuber dry matter (in terms of specific gravity) in these heritage potatoes. The results demonstrated reproducible genotypic variation for starch granule size and shape in tubers with a significant correlation to tuber dry matter in these heritage potato varieties, and offers the possibility for and agronomic relevance of genetic modification of starch granules through selective breeding.     

Spongiotic vesicular dermatitis as a cutaneous reaction pattern in seven horses

Over a 6-year period seven adult horses of different breeds and genders developed multifocal, exudative, oozing dermatitis characterized histologically by epidermal spongiotic vesicles and perivascular eosinophilic, neutrophilic and mixed mononuclear inflammation. Three horses were pruritic. Systemic disease was not noted. Two horses had a history of recurrent urticaria (hives) and one horse had nodules or welt-type lesions that progressed to exudative, oozing lesions. Interepithelial immunoglobulin (Ig)G was detected by avidin-biotin complex-peroxidase staining, but the pattern of staining was more consistent with epithelial oedema than specific IgG deposition associated with pemphigus. The exudative oozing lesions developed under circumstances suggesting that dermal oedema progressed to intracellular and intercellular epidermal oedema, which in turn progressed to the spongiotic vesicular epidermal lesions.     

Does reintroduction stabilize the population of the critically endangered gharial (Gavialis gangeticus,Gavialidae) in Chitwan National Park,Nepal?

• 1 Despite conservation programmes (India 1975, Nepal 1978) gharial populations (Gavialis gangeticus) have declined over their entire distribution range. Information about the current status and main threats is needed to implement effective conservation measures.
• 2 This study presents a survey (2003/2004) of the largest Nepalese gharial population in the Chitwan National Park that has benefited from regular re‐introduction of young gharials since 1981.
• 3 Population size estimates fluctuate between 34 (2003) and 38 (2004). The reintroduction programme, although of limited success, has helped to maintain the gharial population.
• 4 Gharials bask preferentially in large sand banks, and these sites must be protected.
• 5 The main threats are from a dam that causes fish depletion and flushes gharials from the protected area, sand mining and grazing that destroy basking sites, fishing that causes food shortage, drift nets that kill gharial, and water pollution.
• 6 Improvement in the survival of reintroduced gharials is needed. Strict protection of preferred basking sites and prohibition of fishing in the main settling zones are the principal conservation measures while in the long term, education and participatory management by local people are also necessary. Copyright © 2010 John Wiley & Sons, Ltd.

     

Effect of feed restriction on dairy cow milk production: a review

In the dairy cow, negative energy balance affects milk yield and composition as well as animal health. Studying the effects of negative energy balance on dairy cow milk production is thus essential. Feed restriction (FR) experiments attempting to reproduce negative energy balance by reducing the quantity or quality of the diet were conducted in order to better describe the animal physiology changes. The study of FR is also of interest since with climate change issues, cows may be increasingly faced with periods of drought leading to a shortage of forages. The aim of this article is to review the effects of FR during lactation in dairy cows to obtain a better understanding of metabolism changes and how it affects mammary gland activity and milk production and composition. A total of 41 papers studying FR in lactating cows were used to investigate physiological changes induced by these protocols. FR protocols affect the entire animal metabolism as indicated by changes in blood metabolites such as a decrease in glucose concentration and an increase in non-esterified fatty acid or β-hydroxybutyrate concentrations; hormonal regulations such as a decrease in insulin and insulin-like growth factor I or an increase in growth hormone concentrations. These variations indicated a mobilization of body reserve in most studies. FR also affects mammary gland activity through changes in gene expression and could affect mammary cell turnover through cell apoptosis, cell proliferation, and exfoliation of mammary epithelial cells into milk. Because of modifications of the mammary gland and general metabolism, FR decreases milk production and can affect milk composition with decreased lactose and protein concentrations and increased fat concentration. These effects, however, can vary widely depending on the type of restriction, its duration and intensity, or the stage of lactation in which it takes place. Finally, to avoid yield loss and metabolic disorders, it is important to identify reliable biomarkers to monitor energy balance.     

The Role of Pre‐Entry Experience of Firm Founders in Peripheral Regions: Routines,Business Contacts,and Local Starting Conditions

This paper investigates how spinoffs in peripheral regions can profit from the work experience of their founders. More specifically, it discusses which firm routines and business contacts entrepreneurs gather through their prior work experience, and how this experience influences the organizational structure and orientation of the newly founded firm. The transfer of capabilities from parent firm to spinoff has been identified as important aspect of industrial clustering, but empirical evidence from peripheral areas is still sparse. It compares 22 semi‐structured interviews with founders of manufacturing firms from different peripheral regions in Switzerland to investigate whether routine and network transfer differs in varying peripheral contexts. The results show that not only inherited routines are important, but also inherited business contacts. Further, instead of simply reproducing acquired routines and networks, founders employ a mixture of continuity and change to find a good trade‐off between relying on well‐proven practices and introducing novelty. Finally, the geographical proximity of inherited business contacts seems to have an influence on the implementation strategy founders choose. Entrepreneurs with strong inherited local business contacts do not have to invest as much in building up new business contacts as those entrepreneurs in more isolated locations.     

How social organization shapes crop diversity: an ecological anthropology approach among Tharaka farmers of Mount Kenya

The conservation of in situ crop diversity is a key issue to ensure food security. Understanding the processes that shape it is crucial for efficiently managing such diversity. In most rural societies, crop diversity patterns are affected by farmers’ practices of seed exchange, transmission, and selection, but the role of social organization in shaping those practices has been overlooked. This study proposes an ecological anthropology approach to investigate the relation between crop diversity patterns and the social organization of Tharaka farmers in Kenya. The Tharaka are organized in neighborhood-groups, clans, and age-sets. We quantified the influence of these three major social institutions on crop diversity patterns, for both crop species and sorghum landraces. General linear models were used to test the relations between crop species richness and each social factor, while the crop species and sorghum landraces compositions of cropping systems were compared separately through a between-class correspondence analysis. Crop species and sorghum landraces are not randomly distributed among farms, and neighborhood-groups constitute a significant factor organizing crop diversity at both specific and infraspecific levels. Adjacent neighborhood-groups present significantly different crop richness and composition. The results for species were consistent with those obtained for sorghum landraces, confirming that crop diversity was socially structured. The influence of social organization on seed networks and selection processes is discussed.