Conformationally Restricted 2-Substituted Wyosine Derivatives. 1H, 13C,and 15N NMR Study

Abstract

It was found by ¹H, ¹³C and ¹⁵N NMR study that substitution of 4,9-dihydro-4, 6-dimethyl-9-oxo-3-(2′,3′,5′-tri-O-acetyl-β-D-ribofuranosyl) imidazo [1,2-a]purine (wyosine triacetate, 1) at C2 position with electronegative groups CH₃O and C₆H₅CH₂O results in a noticeable electron distribution disturbance in the “left-hand” imidazole ring and a significant increase in the North conformer population of the sugar moiety.     

A novel hypersensitive resistance response against potato virus A in cultivar ’Shepody’

The potato cultivar ’Shepody’ is susceptible to a number of potato viruses including potato virus Y (PVY, potyvirus) but was found to possess extreme resistance to another potyvirus, potato virus A (PVA). ’Shepody’ plants were resistant to PVA infection in manual and graft inoculations. PVA replication was not detected in any of the inoculated plants by ELISA, an infectivity assay and RT-PCR. However, ’Shepody’ plants grafted with shoots containing PVA developed a novel symptomology which resembled a virus infection in appearance and in rate of translocation to the entire plant. Efforts to transmit the symptom-inducing agent manually failed. Graft-inoculation to potato virus indicator plants and PVA-susceptible potato plants showed that the symptom inducer was PVA at an extremely low concentration, detected using RT-PCR followed by Southern blot assay. Tubers from grafted but resistant ’Shepody’ plants had necrotic surfaces and internal spots. PVA was detected from necrotic areas but not from the non-necrotic ones. However, plants resulting from necrotic tubers were free from aerial leaf symptoms observed in grafted plants and produced non-necrotic normal tubers. A trace-back of the parental lineage of ’Shepody’ indicated that the resistance had been introgressed from the cultivar ’Bake King’. Analysis of progeny of a cross of resistant ’Shepody’ to the susceptible ’Goldrus’ indicated that this resistance is controlled by two independent dominant complementary genes in contrast to monogenic resistance reported for other potato viruses. Received: 6 April 1999 / Accepted: 28 July 1999     

A simple stepwise procedure of deriving selection index with restrictions

Summary A simplified alternative procedure was derived for computing selection indices with various restrictions. The procedure involved construction of a sub-index for the unrestricted traits by the conventional methods (Smith-Hazel index approach) and construction of a sub-index for the restricted traits based on the restrospective index approach. The two subindices were then combined to obtain the desired index which met the prespecified restriction. The formulation is straightforward and easy to compute and does not involve the complicated formula as does the derivation of restricted index by the use of the Lagrange multiplier method. As a consequence of simplification, the proposed procedure is approximate in terms of optimal gain in net merit. The procedure presented can also be extended to derive an index with simultaneous imposition of multiple restrictions. Numerical examples were given to illustrate the use of this alternative approach.Animal Research Centre Contribution No. 1251     

Entrainment of Circadian Wheel-Running Rhythms of the Northern Brown Bandicoot, Isoodon macrourus, by Daily Restricted Feeding Schedules

Northern brown bandicoots (Isoodon macrourus) were subjected to restricted feeding for 3 h in the middle of the light period of a 14: 10 light/dark cycle and immediately following this in constant dark. When feeding was restricted to the middle of the light period of the light/dark cycle, all bandicoots maintained a nocturnal activity rhythm. In addition to the nocturnal rhythm, a few bandicoots showed meal-anticipatory activity during the light period. In bandicoots that did not show meal-anticipatory activity, diurnal activity was sometimes evident either during or shortly after the daily meal time. The observation of meal-anticipatory activity in some bandicoots suggests that this species may have a mechanism separate from the light-entrainable mechanism that allows the daily anticipation of periodically available food sources. In the next stage of the experiment, which was in constant dark, the meal was presented at the same time of day as it had been in the previous stage. In all bandicoots, the previously light-entrained component of activity free-ran and was eventually affected by the restricted feeding schedule to some degree. Bandicoots showed weak entrainment and relative coordination, suggesting that restricted feeding is a weak zeitgeber in this species. Evidence also suggesting that two separate but coupled pacemakers control the activity rhythms of the bandicoot was that (a) bandicoots simultaneously showed free-running light-entrainable rhythms and meal-entrained anticipatory rhythms; (b) in several bandicoots, the light-entrainable rhythm was phase advanced when it free-ran through the meal time; and (c) in one bandicoot, meal-entrained anticipatory activity was forced away from the meal time when the previously light-entrained component of activity free-ran through it.     

Long-term restricted index selection in mice designed to change fat content without changing body size

The objective of this study was to determine if low secondary selection differentials, caused by selecting within full-sib families, may have accounted for the failure of an intended restricted selection index to reduce epididymal fat pad weight (EF) without changing body weight (BW) in mice. Replicate lines that had been selected within full-sib families for high (HE) or low (LE) EF, while holding BW constant, were crossed. After two generations of random mating, two replicates were sampled and selection initiated for the same restricted index criteria except that mass selection was used to increase the selection differentials. In both phases of selection the HE restricted index selection, designed to increase EF without altering BW, was in agreement with expectation. In contrast, the LE index, designed to decrease EF without changing BW, did not agree with theory since BW increased while EF decreased only slightly. Therefore, reduced selection differentials could not explain the deviation from theory. A possible explanation may reside in the restricted selection index being more sensitive to changes in genetic parameters due to shifts in gene frequency as a consequence of the selection applied. However, linkage disequilibrium and genetic drift can not be ruled out as contributing factors to the asymmetry of response.The research reported in this publication was funded by the North Carolina Agricultural Research Service (NCARS), Raleigh, NC 27695-7643. Use of trade names in this publication does not imply endorsement by the NCARS of the products named, nor criticism of similar ones not mentioned     

Pasture Quality Affects Juvenile Survival through Reduced Maternal Care in a Mountain‐Dwelling Ungulate

Lactation exerts heavy energetic and physiological costs to mothers, whilst determining early growth and survival of offspring. To mountain ungulates, access to high‐quality forage during nursing and weaning is crucial for reproductive success. We have evaluated the effects of pasture quality on suckling behaviour and winter survival of Apennine chamois Rupicapra pyrenaica ornata kids, across three areas. Areas A‐B (‘poor’ areas) were characterised by a reduced availability of nutritious forage, thus a lower diet quality for female chamois and kids; Area C (a ‘rich’ area) included a much greater availability of nutritious forage. In poor areas, pasture quality has been reduced by climatic and plant composition changes, as well as the presence of a herbivore competitor (red deer Cervus elaphus). In poor areas, we recorded a significantly (1) lower suckling success of chamois kids (number of suckling bouts/number of suck attempts); (2) lower frequency of suckling bouts (n. suckling bouts/kid/h); and (3) lower suckling intensity (suck duration/kid/h) in respect to the rich area. Conversely, frequencies of suckling rejections and those of suckling attempts (n. events/kid/h) were the lowest in the rich area. Winter survival of chamois kids was c. 2 times greater in the rich area (45%) than in poor areas (20–26%). In the poor areas, resource scarcity induced adult female chamois to decrease maternal cares and favour their own maintenance, ultimately affecting population dynamics through kid winter mortality.     

Dairy goat kids fed liquid diets in substitution of goat milk and slaughtered at different ages: an economic viability analysis using Monte Carlo techniques

The aim of this study was to analyze the economic viability of producing dairy goat kids fed liquid diets in alternative of goat milk and slaughtered at two different ages. Forty-eight male newborn Saanen and Alpine kids were selected and allocated to four groups using a completely randomized factorial design: goat milk (GM), cow milk (CM), commercial milk replacer (CMR) and fermented cow colostrum (FC). Each group was then divided into two groups: slaughter at 60 and 90 days of age. The animals received Tifton hay and concentrate ad libitum. The values of total costs of liquid and solid feed plus labor, income and average gross margin were calculated. The data were then analyzed using the Monte Carlo techniques with the @Risk 5.5 software, with 1000 iterations of the variables being studied through the model. The kids fed GM and CMR generated negative profitability values when slaughtered at 60 days (US$ −16.4 and US$ −2.17, respectively) and also at 90 days (US$ −30.8 and US$ −0.18, respectively). The risk analysis showed that there is a 98% probability that profitability would be negative when GM is used. In this regard, CM and FC presented low risk when the kids were slaughtered at 60 days (8.5% and 21.2%, respectively) and an even lower risk when animals were slaughtered at 90 days (5.2% and 3.8%, respectively). The kids fed CM and slaughtered at 90 days presented the highest average gross income (US$ 67.88) and also average gross margin (US$ 18.43/animal). For the 60-day rearing regime to be economically viable, the CMR cost should not exceed 11.47% of the animal-selling price. This implies that the replacer cannot cost more than US$ 0.39 and 0.43/kg for the 60- and 90-day feeding regimes, respectively. The sensitivity analysis showed that the variables with the greatest impact on the final model’s results were animal selling price, liquid diet cost, final weight at slaughter and labor. In conclusion, the production of male dairy goat kids can be economically viable when the kids diet consists mainly of either cow milk or fermented colostrum, especially when kids are slaughtered at 90 days of age.     

Effect of restricted watering and its combination with root pruning on root growth capacity,water status and food reserves ofPinus caribaea var.hondurensis seedlings

Summary Six-month oldPinus caribaea var.hondurensis seedling were subjected to various regimes of restricted watering and their combinations with root pruning to determine a suitable technique of producing seedlings with optimum physiological condition for successful bare-root planting.From the range of treatments tested, plants subjected to watering once every 9 days (D9) were found to be the hardest in terms of highest root growth capacity, leaf water content, root starch content and in having a moderately low transpiration rate.P. caribaea seedlings subjected to this preconditioning treatment may be more able to survive bare-root planting.