bluuebunny/crossref_metadata_2025 huggingface dataset:
Rate of calcium absorption by plant roots and its relation to growth
Authors: Loneragan JF , Snowball K
Published: November 2004

Rates of calcium absorption per unit root weight were measured for each of three successive weeks for 30 grasses, cereals, legumes, and herbs grown in flowing culture solutions of pH 5.7 with a wide range of calcium concentrations (0.3 to 1000 µM) which were maintained constant. Plants did not absorb calcium from 0.3 µM solutions and absorbed little from 0.8 µM solutions. Increasing solution concentrations from 0.8 to 10 µM increased the average rates of calcium absorption almost linearly in all plant groups: increasing solution concentrations to 100 or 1000 µM increased rates of calcium absorption but with decreasing effectiveness. Rates of absorption generally remained constant during the experiment, except that in grasses and cereals at 100 and 1000 µM calcium they tended to fall with time. At concentrations from 2.5 to 1000 µM, the average rates of calcium absorption by roots of legumes and herbs were generally very much higher than those by equal weights of grass and cereal roots. Individual cultivars within each plant group tended to follow the average behaviour, so that almost all legumes and herbs absorbed calcium very much faster (up to 15 times) than grasses and cereals at all solution concentrations above 2.5 µM. The relationship between rates of calcium absorption and plant growth is discussed. Since excess calcium accumulated in plants is not readily mobilized to developing tissues, plants become calcium-deficient as soon as the rate of calcium absorption falls below the functional requirements of the tissues. Absorption rater of 0.5 µg atom in grasses and cereals, and in herbs and legumes of 1 µg atom per gram fresh roots per day are suggested as minimal to maintain relative growth rates of c. 9% per day. In standard culture solutions legumes and herbs would deplete calcium from solution and hence develop calcium deficiency more quickly than cereals and grasses. By contrast, in flowing culture solutions with low calcium concentrations maintained constant, high rates of calcium absorption by legumes and herbs sometimes offset their high tissue requirements for calcium; this explains why some legumes and herbs are able to grow at lower calcium concentrations than some grasses and cereals. It is suggested that conditions of calcium supply under which deficiency develops in solutions and in soils should be taken into account when assessing the relative susceptibility of plant species to calcium deficiency.
Some factors associated with the behaviour and survival of newly shorn sheep
Authors: Hutchinson KJ , McRae BH
Published: November 2004

Sheep deaths in the 12-day period following shearing were related to a high rate of body weight loss during the 4 weeks before shearing. The body weight or body condition of sheep at shearing was unimportant. Mortality level was not influenced by the amount of herbage available after shearing although the grazing activities of the survivors increased. Mortality was associated with a massive infiltration of lipid into the zona fasciculata of the adrenal cortex.The shorn sheep spent more time standing and less time grazing during the night. These results are discussed in relation to possible management practices to reduce sheep losses.
Comparative responses to manganese excess of eight tropical and four temperate pasture legume species
Authors: Andrew CS , Hegarty MP
Published: November 2004

Eight tropical legumes and four temperate legumes were grown in water culture and their response to excess manganese was determined by comparing relative dry matter production (tops and roots), manganese, calcium, and nitrogen percentages in the dry matter. The tropical legumes as a group were as much affected by excess manganese as the temperate legumes. There were varying degrees of tolerance within each group. The growth of the different species varied over a wide range but this had nothing to do with sensitivity to manganese. The concentrations of manganese in the roots of two species representing the most tolerant and the least tolerant species were examined. They suggested that the relative tolerance of species depends in part on retention of manganese within the root system. Manganese treatments had little effect on the calcium and nitrogen concentrations in the dry matter (tops) of the majority of species examined. The diagnosis of manganese toxicity may be made by comparing manganese concentrations in the tops with toxicity threshold values obtained by the authors and other workers, and used in conjunction with the visual symptoms of manganese toxicity which have been observed for the various species. Toxicity threshold manganese values in the dry matter of the tops obtained in this investigation were: Centrosema pubescens 1600, Stylosanthes humilis 1140, Lotononis bainesii 1320, Phaseolus lathyroides 840, Leucaena leucocephala 550, Desmodium uncinatum 1160, Glycine javanica 560, Phaseolus atropurpureus 810, Trifolium repens 650, Medicago sativa 380, Trifolium fragiferum 510, and Medicago truncatula 560 p.p.m.
The nitrogen nutrition of the peach tree. IV. Storage and mobilization of nitrogen in mature trees
Authors: Taylor BK , van den Ende B
Published: November 2004

An experiment was carried out on 8-year-old peach trees in the field to further study the chemical composition of storage nitrogen in mature trees and to relate tree performance in one growing season to the level of storage nitrogen in tree tissues during the previous winter. Storage nitrogen in dormant trees consisted mainly of soluble organic nitrogen, and free arginine was a principal constituent of this fraction. The arginine nitrogen content of the soluble nitrogen fraction increased with increasing nitrogen supply, but values were low compared with those found in young peach trees. The concentration of arginine in roots of dormant trees was the most sensitive indicator of the nitrogen status of the trees. In comparison, conventional leaf analysis for total nitrogen in midsummer was only about one-half as sensitive as an index of nitrogen status. Since there could be objections to using root tissue for analysis it is of interest to note that the next best estimate of the nitrogen status of the trees was given by the level of arginine nitrogen in leaf + flower buds. The growth of new shoots and especially the nitrogen content of leaves were in proportion to the levcl of storage nitrogen in dormant trees before growth commenced. However, flowering performance and fruit set per tree were not dependent upon the level of storage nitrogen in the trees. Flowers at full bloom from nil nitrogen and plus nitrogen treatments contained approximately the same content of total nitrogen and this may be the reason why nitrogen treatments did not influence fruit set. Nitrogen analyses and field observations indicated that stored nitrogen in nil nitrogen trees was preferentially used for reproductive processes rather than for vegetative growth. The amount of total nitrogen per leaf first increased and then decreased with elapsed time during the growing season. This latter loss was attributed to migration of nitrogen from ageing leaves to fruits and/or woody tissues in late summer and early autumn. Nitrogen treatment did not significantly alter the proportion of total nitrogen lost per leaf at this time, but the amount of total nitrogen lost per leaf usually increased with increasing nitrogen supply. Results are compared with those obtained in earlier work and the importance of reaccumulation of nitrogen from abscising leaves in the nitrogen economy of the trees is briefly discussed.
The requirement for cobalt of sheep grazed on cobalt-deficient pastures
Authors: Lee JJ , Marston HR
Published: November 2004

Experimental proof is presented that cobalt injected intravenously or into the abomasum at the rate of 1 mg/day is without any measurable effect on the cobalt deficiency syndrome in sheep. Similarly, depot therapy with colloidal cobalt is of no benefit. It is confirmed that, to be effective, cobalt supplements must be introduced frequently into the rumen, by mouth or by direct injection; although administration by other routes leads to a considerable accumulation of cobalt in the tissues this does not reach the rumen in effective amounts, if at all. For sheep grazing grossly cobalt-deficient pastures the total intake of cobalt necessary to ensure optimum growth and haemoglobin production was found to be equivalent to almost precisely 0.08 mg/day when supplementary cobalt was provided three times each week; in growing lambs the requirement was greater. Analytical evidence is presented in support and the findings are discussed in relation to certain conclusions arrived at by others.
Prospects for manipulating the vegetative-reproductive balance in horticultural crops through nitrogen nutrition: a review
Authors: Huett DO
Published: November 2004

This review examines the prospects for manipulating the vegetative-reproductive balance in horticultural crops through nitrogen (N) nutrition. It also examines whether incorrect timing or excessive applications of N stimulate vegetative growth at the expense of reproductive growth. Productivity of horticultural crops is dependent on an adequate N status because photosynthetic capacity is dependent on leaf N content per unit area. Efficient N uptake occurs during periods of active growth and depends on active photosynthesis. Most N in exposed leaves is accumulated as protein and the uptake and conversion to protein requires a carbohydrate (CHO) supply. A feedback mechanism has been proposed from shoots to roots in the control of N uptake, because ammonium and nitrate uptake do not increase at supraoptimal concentrations. Stored CHO and nutrients support actively growing shoots and inflorescences and while vegetative and reproductive meristems compete as sinks, fruit growth depends principally on current photosynthesis. Most of the season's N uptake by deciduous trees occurs during the post-fruit maturity period in late summer and autumn in vegetative growth which is remobilized prior to leaf fall in late autumn into storage. The N is redistributed the following spring to support new season leaf and fruit growth. In sand culture studies conducted with 2-year-old peach and apple trees, an N deficiency which led to inadequate tree N reserves in winter inhibited flowering, fruit set and vegetative growth the following spring. N applied during spring is poorly assimilated. For Prunus spp., 90% of the N contained in the spring vegetative flush is derived from storage, indicating that exogenous N applications at that time are unlikely to influence that season's growth. Vegetable crops which have high growth and N uptake rates compared with tree fruit crops (maximum N uptake rate for tomato 66 kg/ha.week v. peach 1.3 kg/ha.week) rely on exogenous N and current photosynthesis to support growth. In studies where very high N rates were applied to horticultural crops, tree crops were unaffected except in citrus where yield was depressed and tree size was unaffected. The growth and yield of most vegetable crops were depressed at high N rates while at these high N rates, tomato yields were increased while vegetative growth was unaffected. Where a depression in tomato growth occurred at high N rates, it was caused by a salt effect, although chloride at the same osmotic potential depresses growth much more than nitrate. In subtropical fruit and nut crops such as lychee, macadamia and avocado, timing and rate of N were not detrimental to yield. Soil N, tree N and CHO reserves buffer against an external N supply and hence the ability of applied N to manipulate the vegetative-reproductive balance. More work is required to establish the extent and subsequent effect of competition between the vegetative flushes and inflorescence growth for subtropical fruit crops in particular.
Rumen physiology: the key to understanding the conversion of plants into animal products
Authors: Faichney GJ
Published: November 2004

Ruminants have always provided meat, hides and fibre for human use, and since the development of agriculture with its associated domestication of herding ruminants, they have also provided milk and draught power. Sound interpretation of the observations of animal behaviour and performance made by the early hunters and stockmen was not possible until knowledge of physiology began to accumulate in the 18th and 19th centuries. The development of new methods about 50 years ago led to the modern era of ruminant physiology, a flowering of research which has continued to the present day. Rumen physiology is intrinsically interesting but it also has utility because it is fundamental to the understanding of ruminant nutrition. Research must continue, particularly in the areas of microbial ecology and particle kinetics, if the ruminant industries are to respond adequately to the need to produce more food for humans from non-arable land and by-products, to increase product quality, to tailor products to market requirements and, in doing so, reduce their environmental impact
Have changes in yield (1900-1992) been accompanied by a decreased yield stability in Australian cereal production?
Authors: Slafer GA , Kernich GC
Published: November 2004

Regression analyses of the relationships between yield and time over the last century were conducted for wheat, barley, oats, maize, and rice at a national level and those for the three winter cereals in New South Wales (NSW), Victoria (Vic), South Australia (SA), Western Australia (WA), and Queensland (Qld). The fitted function accounts for the impact of agronomic improvement on yield and the residuals stand for the variability of yield beyond this impact. Another measure of the stability was obtained by considering the residuals as a proportion of actual yield ('relative residuals'). Crops varied greatly in their yields but there was no relationship between the coefficient of variation and average yield amongst these cereals. As expected, yields of all five crops are presently higher than early this century. The residuals and relative residuals for each crop were plotted against years. Residuals of wheat yields over time showed no increase or decrease during the century, but the relative residuals exhibited a clear trend towards an increased yield stability. Barley and oats showed sirnilar patterns to those of wheat. Residuals of maize yields increased with time, but relative residuals remained unchanged. Rice yields exhibited the largest residuals, but no trends with time. Yield stability, measured as a proportion of yield, has been clearly improved during this century. Yield trends for the winter cereals at a State level confirmed the results observed at a national level. In conclusion, yields of newer cultivars grown under modern management were higher and more stable, or at least not less stable, than those of crops grown early in the century. Across States and crops, there was no relationship between yield stability and yield.
A comparison of four serological tests for the detection of banana bunchy top virus in banana
Authors: Geering ADW , Thomas JE
Published: November 2004

Four different serological tests for detection of banana bunchy top virus (BBTV) in banana sap are compared: (i) a triple-antibody sandwich ELISA for BBTV, utilising anti-BBTV polyclonal antibodies for virus capture, and anti-BBTV monoclonal antibodies, alkaline phosphatase-labelled sheep anti-mouse antibodies, and p-nitrophenyl phosphate for detection (ELISA-NPP); (ii) an alternative enzyme-substrate system for ELISA involving an amplification step (AmpakTM enzyme amplification kit) (ELISA-A); (iii) a colorimetric dot immunobinding assay (DIBA-C), in which the enzyme-substrate system was alkaline phosphatase and nitroblue tetrazolium/5-bromo-4-chloro-3-indolyl-phosphate; (iv) an enhanced chemiluminescent form (DIBA-ECL), in which the enzyme-substrate system was horseradish peroxidase and luminol. For both DIBA-C and DIBA-ECL, maximum sensitivity was obtained by pre-coating the nitrocellulose membrane with anti-BBTV polyclonal antibodies, by using 0.05 M sodium carbonate (pH 9.6) as the coating buffer, and by clarifying the sap by centrifugation and extraction with chloroform or dichloroniethane. Treatment of the sap before centrifugation by snap-freezing at -70�C, or heating at either 30 or 50�C for 10 min, had no effect on sensitivity; heating at 70�C for 10 min eliminated antigenicity. ELISA-NPP, ELISA-A, and DIBA-ECL had equivalent sensitivity, but DIBA-C was up to 8-fold less sensitive than the former 3 assays. ELISA-NPP was adjudged to be the best compromise between sensitivity, cost and completion time.
The production and short chain fatty acid composition of lipid from cashmere goat buck fleece
Authors: Hillbrick GC , Tucker DJ
Published: November 2004

This study examined the lipid content and short chain fatty acid composition of fleece samples collected from Cashmere goat (Capra hircus laniger) bucks at various times throughout the year. Fleece samples from does and gonadectomised goats were also analysed at one time during the breeding season for comparison. Lipid was extracted with chloroform/methanol azeotrope, saponified, and analysed for short chain fatty acids (C2-Clo) by gas chromatography and gas chromatography/mass spectrometry. Bucks had increased amounts of lipid and ethyl-branched fatty acids in fleece samples shorn from March to September, compared with fleece samples shorn in November and January. The increases in the amounts of lipid and ethyl-branched fatty acids corresponded with the breeding season and the period when the buck odour was increased. This supports the assumption that ethyl-branched fatty acids may be a pheromone in goats.
Seedling emergence and survival of annual pasture legumes in northern New South Wales
Authors: Lodge GM
Published: November 2004

Seedling emergence and survival of 15 annual pasture legumes was studied in the field at Tamworth, northern New South Wales. Emergence was measured in permanent quadrats (0.09 m2) in covered and uncovered areas approximately every 15 days from 30 November 1983 to 30 November 1984. Survival of seedlings was estimated from 15 December 1983 to 31 August 1984, before plants senesced. Emergence was generally highest in summer and autumn following seed set and lowest in winter and spring. Two legumes, Medicago scutellata cv. Sava and Trifolium subterraneum cv. Seaton Park, had high emergence in winter (mid July). Total seedling emergence was highest ( P < 0.05) in covered areas of cv. Seaton Park and uncovered areas of T. hirtum cv. Hykon. All T. subterraneum cultivars, M. minima, Astragalus hamosus cv. Ioman, Vicia villosa cv. Namoi, and M. truncatula cv. Paraggio had higher total emergence in covered compared with uncovered areas. In contrast, total emergence of M. aculeata, M. truncatula cv. Jemalong, Sava, and Hykon was lowest in covered areas. Cover had little effect on the total emergence of M. truncatula cv. Sephi and T. glomeratum. Of the 7700 individual seedlings marked from November 1983 to August 1984, a mean of only 31% (covered) and 41% (uncovered) survived until 31 August 1984. For each emergence time, highest ( P < 0.05) survival rate coincided with the highest (P < 0.05) number of emerged seedlings in 4 of the legumes in covered areas (cv. Namoi, 31 January; cv. Ioman, 31 March; cv. Hykon, 15 April; cv. Sava, 15 July; Table 4) and 9 in uncovered areas (cvv. Nungarin, Seaton Park, and Namoi, 31 January; M. aculeata and cv. Sephi, 28 February; cvv. Jemalong and Ioman, 31 March; T. glomeratum, 15 April; cv. Sava, 15 July). In all other legumes there was no optimum time for emergence, since the highest (P < 0.05) survival rates were associated with seedling survivals <50%. Generally, survival curves with a mortality constant rather than a mortality rate were a better fit ( P < 0.05) for most legumes and times. This implied that these survival curves were determined at the time of recruitment, and declined at a constant rate, despite below-average post-emergence rainfall in May-June. Low rates of survival at times of highest ( P < 0.05) emergence indicated that there may have been some density-dependent regulation in some of the legumes.
Long-range compaction and flexibility of interphase chromatin in budding yeast analyzed by high-resolution imaging techniques
Authors: Bystricky Kerstin , Heun Patrick , Gehlen Lutz , Langowski Jörg , Gasser Susan M.
Published: November 2004

Little is known about how chromatin folds in its native state. Using optimized
in situ
hybridization and live imaging techniques have determined compaction ratios and fiber flexibility for interphase chromatin in budding yeast. Unlike previous studies, ours examines nonrepetitive chromatin at intervals short enough to be meaningful for yeast chromosomes and functional domains in higher eukaryotes. We reconcile high-resolution fluorescence
in situ
hybridization data from intervals of 14–100 kb along single chromatids with measurements of whole chromosome arms (122–623 kb in length), monitored in intact cells through the targeted binding of bacterial repressors fused to GFP derivatives. The results are interpreted with a flexible polymer model and suggest that interphase chromatin exists in a compact higher-order conformation with a persistence length of 170–220 nm and a mass density of ≈110–150 bp/nm. These values are equivalent to 7–10 nucleosomes per 11-nm turn within a 30-nm-like fiber structure. Comparison of long and short chromatid arm measurements demonstrates that chromatin fiber extension is also influenced by nuclear geometry. The observation of this surprisingly compact chromatin structure for transcriptionally competent chromatin in living yeast cells suggests that the passage of RNA polymerase II requires a very transient unfolding of higher-order chromatin structure.
Mitochondrial biogenesis by NO yields functionally active mitochondria in mammals
Authors: Nisoli Enzo , Falcone Sestina , Tonello Cristina , Cozzi Valeria , Palomba Letizia , Fiorani Mara , Pisconti Addolorata , Brunelli Silvia , Cardile Annalisa , Francolini Maura , Cantoni Orazio , Carruba Michele O. , Moncada Salvador , Clementi Emilio
Published: November 2004

We recently found that long-term exposure to nitric oxide (NO) triggers mitochondrial biogenesis in mammalian cells and tissues by activation of guanylate cyclase and generation of cGMP. Here, we report that the NO/cGMP-dependent mitochondrial biogenesis is associated with enhanced coupled respiration and content of ATP in U937, L6, and PC12 cells. The observed increase in ATP content depended entirely on oxidative phosphorylation, because ATP formation by glycolysis was unchanged. Brain, kidney, liver, heart, and gastrocnemius muscle from endothelial NO synthase null mutant mice displayed markedly reduced mitochondrial content associated with significantly lower oxygen consumption and ATP content. In these tissues, ultrastructural analyses revealed significantly smaller mitochondria. Furthermore, a significant reduction in the number of mitochondria was observed in the subsarcolemmal region of the gastrocnemius muscle. We conclude that NO/cGMP stimulates mitochondrial biogenesis, both
in vitro
and
in vivo
, and that this stimulation is associated with increased mitochondrial function, resulting in enhanced formation of ATP.
TATA box binding protein induces structure in the recombinant glucocorticoid receptor AF1 domain
Authors: Kumar Raj , Volk David E. , Li Jianquan , Lee James C. , Gorenstein David G. , Thompson E. Brad
Published: November 2004

A number of transcription factor proteins contain domains that are fully or partially unstructured. The means by which such proteins acquire naturally folded conformations are not well understood. When they encounter their proper binding partner(s), several of these proteins adopt a folded conformation through an induced-fit mechanism. The glucocorticoid receptor (GR) is a ligand-activated transcription factor. Expressed independently as a recombinant peptide, the N-terminal transactivation domain (AF1) of the GR shows little structure and appears to exist as a collection of random coil configurations. The GR AF1 is known to interact with other transcription factors, including a critical component of the general transcription machinery proteins, the TATA box binding protein (TBP). We tested whether this interaction can lead to acquisition of structure in the GR AF1. Our results show that recombinant GR AF1 acquires a significant amount of helical content when it interacts with TBP. These structural changes were monitored by Fourier transform infrared and NMR spectroscopies, and by proteolytic digestions. Our results support a model in which TBP binding interaction with the GR AF1 induces significantly greater helical structure in the AF1 domain. This increased helical content in the GR AF1 appears to come mostly at the expense of random coil conformation. These results are in accordance with the hypothesis that an induced-fit mechanism gives structure to the GR AF1 when it encounters TBP.
TNF receptor-associated factor (TRAF) domain and Bcl-2 cooperate to induce small B cell lymphoma/chronic lymphocytic leukemia in transgenic mice
Authors: Zapata Juan M. , Krajewska Maryla , Morse Herbert C. , Choi Yongwon , Reed John C.
Published: November 2004

Transgenic mice overexpressing in B lymphocytes either Bcl-2 or a TNF receptor-associated factor (TRAF)2 mutant lacking the N-terminal RING and zinc finger domains located at the N terminus of the molecule (TRAF2DN), which mimics TRAF1, developed lymphadenopathy and splenomegaly due to polyclonal B cell expansion. Remarkably, TRAF2DN/Bcl-2 double-transgenic mice contained B cell populations similar to those observed in TRAF2DN mice. However, over time, they developed severe splenomegaly and lymphadenopathy, and most animals also developed leukemia, pleural effusion, and, in some cases, ascites associated with monoclonal and oligoclonal B cell neoplasms. The life span of TRAF2DN/Bcl-2 mice was markedly reduced compared with Bcl-2 and TRAF2DN single-transgenics or wild-type littermates. The expanded B cell population of TRAF2DN/Bcl-2 double-transgenic mice was primarily comprised of small/medium-size noncycling B220
M
/IgM
H
/IgD
L
/CD21
L
/CD23
NULL
/CD11b
+
/CD5
+
cells that were Bcl-6-negative, consistent with a B-1 phenotype. The cells also expressed high levels of CD54 and other adhesion molecules.
In vitro
, these B cells showed comparable proliferation rates to those of wild-type counterparts but exhibited markedly increased survival and were resistant to apoptosis induced by chemotherapeutic agents and glucocorticoids. Histopathologic features were consistent with mouse small B cell lymphoma progressing to leukemia with many similarities to human chronic lymphocytic leukemia. Given that many human chronic lymphocytic leukemias overexpress TRAF1 and Bcl-2, our findings suggest that cooperation between Bcl-2 and TRAF pathways contributes to the development of this type of leukemia.
Molecular evolution of dinoflagellate luciferases, enzymes with three catalytic domains in a single polypeptide
Authors: Liu Liyun , Wilson Thérèse , Hastings J. Woodland
Published: November 2004

Enzymes with multiple catalytic sites are rare, and their evolutionary significance remains to be established. This study of luciferases from seven dinoflagellate species examines the previously undescribed evolution of such proteins. All these enzymes have the same unique structure: three homologous domains, each with catalytic activity, preceded by an N-terminal region of unknown function. Both pairwise comparison and phylogenetic inference indicate that the similarity of the corresponding individual domains between species is greater than that between the three different domains of each polypeptide. Trees constructed from each of the three individual domains are congruent with the tree of the full-length coding sequence. Luciferase and ribosomal DNA trees both indicate that the
Lingulodinium polyedrum
luciferase diverged early from the other six. In all species, the amino acid sequence in the central regions of the three domains is strongly conserved, suggesting it as the catalytic site. Synonymous substitution rates also are greatly reduced in the central regions of two species but not in the other five. This lineage-specific difference in synonymous substitution rates in the central region of the domains correlates inversely with the content of GC
3,
which can be accounted for by the biased usage toward C-ending codons at the degenerate sites. RNA modeling of the central region of the
L. polyedrum
luciferase domain suggests a function of the constrained synonymous substitutions in the circadian-controlled protein synthesis.
Correlates of fruit and vegetable intake among Norwegian schoolchildren: parental and self-reports
Authors: Bere Elling , Klepp Knut-Inge
Published: November 2004

Objectives:

To identify correlates of 6th and 7th graders' (age 10–12 years) fruit and vegetable intake, to investigate parent–child correlations of fruit and vegetable intake, and to compare parents' and children's reports of children's accessibility, skills and preferences with respect to fruit and vegetables.

Design:

The results presented are based on the baseline survey of the ‘Fruits and Vegetables Make the Marks Project’, where 38 schools participated.

Setting:

Fruit and vegetable intake was measured by food frequency questions. Theoretical factors, based on Social Cognitive Theory, potentially correlated to intake were measured, including behavioural skills, accessibility, modelling, intention, preferences, self-efficacy and awareness of 5-a-day recommendations.

Subjects:

In total, 1950 (participation rate 85%) 6th and 7th graders and 1647 of their parents participated.

Results:

Overall, 34% of the variance in the pupils' reported fruit and vegetable intake was explained by the measured factors. The strongest correlates to fruit and vegetable intake were preferences and accessibility. The correlation between the children's and their parents' fruit and vegetable intake was 0.23. The parents perceived their children's accessibility to be better than what was reported by the children (P<0.01), while the children reported their skills to be better than what was perceived by their parents (P<0.01).

Conclusion:

The results from this study clearly point to a need for nutrition interventions aimed at parents. An important next step will be to investigate whether the identified correlates predict future fruit and vegetable intake, and whether they mediate any changes in intake in an intervention study.
The nutritional status of asymptomatic HIV-infected Africans: directions for dietary intervention?
Authors: Vorster Hester H , Kruger Annamarie , Margetts Barrie M , Venter Christina S , Kruger H Salomé , Veldman Frederick J , MacIntyre Una E
Published: November 2004

Objective:

To compare the relationships between food (nutrient) intakes and biochemical markers of nutritional status of asymptomatic HIV-infected with HIV-uninfected subjects, to gain more information on the appropriate diet for HIV-infected persons at an early stage of infection.

Design:

Cross-sectional population-based survey.

Setting:

North West Province, South Africa.

Subjects:

Two hundred and sixteen asymptomatic HIV-infected and 1550 HIV-uninfected men and women volunteers aged 15 years and older, recruited as ‘apparently healthy’ subjects from 37 randomly selected sites.

Outcome measures:

Food and nutrient intakes, measured with a validated food-frequency questionnaire, and nutritional status indicated by anthropometric and biochemical variables, measured by a standardised methodology.

Results:

The prevalence of HIV infection in the study population was 11.9%. The anthropometric indices and nutrient intakes of HIV-infected and uninfected subjects did not differ significantly, indicating that these 216 HIV-infected subjects were at an early stage of infection. Of the biochemical nutritional status variables, high-density lipoprotein cholesterol and total cholesterol, haemoglobin, albumin and triglycerides were significantly lower in infected subjects. They also had higher globulin and liver enzyme levels than uninfected subjects. In infected subjects, serum albumin correlated significantly with serum lipids, serum vitamin A, serum vitamin E, serum iron, total iron-binding capacity and haemoglobin. The significant positive correlations of the liver enzymes with serum lipids, albumin, vitamin A and iron, observed in HIV-uninfected subjects, disappeared in the infected subjects. Polyunsaturated fat intake showed significant positive correlations with the increased liver enzymes in infected subjects. A principal components analysis indicated that, in infected subjects, increased liver enzymes correlated with higher consumption of maize meal and lower consumption of meat and vegetables.

Conclusions and recommendations:

This survey indicated that asymptomatic HIV-infected subjects who followed a diet rich in animal foods had smaller decreases in serum albumin, haemoglobin and lipid variables, and smaller increases in liver enzymes, than those who consumed a diet based on staple foods. This suggests that animal foods are associated with improved nutritional status in HIV-infected persons. These results should be confirmed with intervention studies before dietary recommendations for asymptomatic HIV-infected individuals can be made.
Ubiquitin charging of human class III ubiquitin-conjugating enzymes triggers their nuclear import
Authors: Plafker Scott M. , Plafker Kendra S. , Weissman Allan M. , Macara Ian G.
Published: November 2004

Ubiquitin is a small polypeptide that is conjugated to proteins and commonly serves as a degradation signal. The attachment of ubiquitin (Ub) to a substrate proceeds through a multi-enzyme cascade involving an activating enzyme (E1), a conjugating enzyme (E2), and a protein ligase (E3). We previously demonstrated that a murine E2, UbcM2, is imported into nuclei by the transport receptor importin-11. We now show that the import mechanism for UbcM2 and two other human class III E2s (UbcH6 and UBE2E2) uniquely requires the covalent attachment of Ub to the active site cysteine of these enzymes. This coupling of E2 activation and transport arises from the selective interaction of importin-11 with the Ub-loaded forms of these enzymes. Together, these findings reveal that Ub charging can function as a nuclear import trigger, and identify a novel link between E2 regulation and karyopherin-mediated transport.
Control of mitochondrial motility and distribution by the calcium signal
Authors: Yi Muqing , Weaver David , Hajnóczky György
Published: November 2004

Mitochondria are dynamic organelles in cells. The control of mitochondrial motility by signaling mechanisms and the significance of rapid changes in motility remains elusive. In cardiac myoblasts, mitochondria were observed close to the microtubular array and displayed both short- and long-range movements along microtubules. By clamping cytoplasmic [Ca2+] ([Ca2+]c) at various levels, mitochondrial motility was found to be regulated by Ca2+ in the physiological range. Maximal movement was obtained at resting [Ca2+]c with complete arrest at 1–2 μM. Movement was fully recovered by returning to resting [Ca2+]c, and inhibition could be repeated with no apparent desensitization. The inositol 1,4,5-trisphosphate– or ryanodine receptor-mediated [Ca2+]c signal also induced a decrease in mitochondrial motility. This decrease followed the spatial and temporal pattern of the [Ca2+]c signal. Diminished mitochondrial motility in the region of the [Ca2+]c rise promotes recruitment of mitochondria to enhance local Ca2+ buffering and energy supply. This mechanism may provide a novel homeostatic circuit in calcium signaling.
The RNA-binding protein SUP-12 controls muscle-specific splicing of the ADF/cofilin pre-mRNA in C. elegans
Authors: Anyanful Akwasi , Ono Kanako , Johnsen Robert C. , Ly Hinh , Jensen Victor , Baillie David L. , Ono Shoichiro
Published: November 2004

Tissue-specific alternative pre-mRNA splicing is essential for increasing diversity of functionally different gene products. In Caenorhabditis elegans, UNC-60A and UNC-60B, nonmuscle and muscle isoforms of actin depolymerizing factor (ADF)/cofilin, are expressed by alternative splicing of unc-60 and regulate distinct actin-dependent developmental processes. We report that SUP-12, a member of a new family of RNA recognition motif (RRM) proteins, including SEB-4, regulates muscle-specific splicing of unc-60. In sup-12 mutants, expression of UNC-60B is decreased, whereas UNC-60A is up-regulated in muscle. sup-12 mutations strongly suppress muscle defects in unc-60B mutants by allowing expression of UNC-60A in muscle that can substitute for UNC-60B, thus unmasking their functional redundancy. SUP-12 is expressed in muscle and localized to the nuclei in a speckled pattern. The RRM domain of SUP-12 binds to several sites of the unc-60 pre-mRNA including the UG repeats near the 3′-splice site in the first intron. Our results suggest that SUP-12 is a novel tissue-specific splicing factor and regulates functional redundancy among ADF/cofilin isoforms.
Impact of telomerase ablation on organismal viability, aging, and tumorigenesis in mice lacking the DNA repair proteins PARP-1, Ku86, or DNA-PKcs
Authors: Espejel Silvia , Klatt Peter , Murcia Josiane Ménissier-de , Martín-Caballero Juan , Flores Juana M. , Taccioli Guillermo , de Murcia Gilbert , Blasco María A.
Published: November 2004

The DNA repair proteins poly(ADP-ribose) polymerase-1 (PARP-1), Ku86, and catalytic subunit of DNA-PK (DNA-PKcs) have been involved in telomere metabolism. To genetically dissect the impact of these activities on telomere function, as well as organismal cancer and aging, we have generated mice doubly deficient for both telomerase and any of the mentioned DNA repair proteins, PARP-1, Ku86, or DNA-PKcs. First, we show that abrogation of PARP-1 in the absence of telomerase does not affect the rate of telomere shortening, telomere capping, or organismal viability compared with single telomerase-deficient controls. Thus, PARP-1 does not have a major role in telomere metabolism, not even in the context of telomerase deficiency. In contrast, mice doubly deficient for telomerase and either Ku86 or DNA-PKcs manifest accelerated loss of organismal viability compared with single telomerase-deficient mice. Interestingly, this loss of organismal viability correlates with proliferative defects and age-related pathologies, but not with increased incidence of cancer. These results support the notion that absence of telomerase and short telomeres in combination with DNA repair deficiencies accelerate the aging process without impacting on tumorigenesis.
Block of Inactivation-deficient Na+ Channels by Local Anesthetics in Stably Transfected Mammalian Cells
Authors: Wang Sho-Ya , Mitchell Jane , Moczydlowski Edward , Wang Ging Kuo
Published: November 2004

According to the classic modulated receptor hypothesis, local anesthetics (LAs) such as benzocaine and lidocaine bind preferentially to fast-inactivated Na+ channels with higher affinities. However, an alternative view suggests that activation of Na+ channels plays a crucial role in promoting high-affinity LA binding and that fast inactivation per se is not a prerequisite for LA preferential binding. We investigated the role of activation in LA action in inactivation-deficient rat muscle Na+ channels (rNav1.4-L435W/L437C/A438W) expressed in stably transfected Hek293 cells. The 50% inhibitory concentrations (IC50) for the open-channel block at +30 mV by lidocaine and benzocaine were 20.9 ± 3.3 μM (n = 5) and 81.7 ± 10.6 μM (n = 5), respectively; both were comparable to inactivated-channel affinities. In comparison, IC50 values for resting-channel block at −140 mV were >12-fold higher than those for open-channel block. With 300 μM benzocaine, rapid time-dependent block (τ ≈ 0.8 ms) of inactivation-deficient Na+ currents occurred at +30 mV, but such a rapid time-dependent block was not evident at −30 mV. The peak current at −30 mV, however, was reduced more severely than that at +30 mV. This phenomenon suggested that the LA block of intermediate closed states took place notably when channel activation was slow. Such closed-channel block also readily accounted for the LA-induced hyperpolarizing shift in the conventional steady-state inactivation measurement. Our data together illustrate that the Na+ channel activation pathway, including most, if not all, transient intermediate closed states and the final open state, promotes high-affinity LA binding.
Glutathione S‐Transferase 8‐8 Expression Is Lower in Alcohol‐Preferring Than in Alcohol‐Nonpreferring Rats
Authors: Liang Tiebing , Habegger Kirk , Spence John P. , Foroud Tatiana , Ellison Julie A. , Lumeng Lawrence , Li Ting‐Kai , Carr Lucinda G.
Published: November 2004

Objective: A primary focus of alcohol research is to provide novel targets for alcohol treatment by identifying genes that predispose individuals to drink alcohol. Animal models of alcoholism developed by selective breeding are invaluable tools to elucidate both the genetic nature and the underlying biological mechanisms that contribute to alcohol dependence. These selected lines (high alcohol preferring and low alcohol preferring) display phenotypic and genetic differences that can be studied to further our understanding of alcohol preference and related genetic traits. By combining molecular techniques, genetic and physiological factors that underlie the cause of alcoholism can be identified.

Methods: Total gene expression analysis was used to identify genes that are differentially expressed in specific brain regions between alcohol‐naïve, inbred alcohol‐preferring (iP) and ‐nonpreferring (iNP) rats. Quantitative reverse transcriptase–polymerase chain reaction, in situ hybridization, Western blot, and sequence analysis were used to further characterize rat glutathione S‐transferase 8‐8 (rGST 8‐8).

Results: Lower expression of rGST 8‐8 mRNA was observed in discrete brain regions of iP compared with iNP animals, and these expression differences were confirmed. To determine additional expression patterns of rGST 8‐8, we used in situ hybridization. Rat GST 8‐8 was highly expressed in hippocampus, the choroid plexus of the dorsal third ventricle and the lateral ventricle, and ependymal cells along the dorsal third ventricle and the third ventricle. Western blot analysis showed that rGST 8‐8 protein levels were lower in the hippocampus and the amygdala of iP compared with iNP. A silent single‐nucleotide polymorphism in the coding region and three single‐nucleotide polymorphisms in the 3′‐UTR were identified in the rGST 8‐8 cDNA.

Conclusion: There is regional variation of rGST 8‐8 expression in the brain, at both the mRNA and protein level, and the iP strain has lower innate rGST 8‐8 levels than the iNP strain in discrete brain regions.
Maternal Age, Alcohol Abuse History, and Quality of Parenting as Moderators of the Effects of Prenatal Alcohol Exposure on 7.5‐Year Intellectual Function
Authors: Jacobson Sandra W. , Jacobson Joseph L. , Sokol Robert J. , Chiodo Lisa M. , Corobana Raluca
Published: November 2004

Background: In contrast to the extensive literature documenting IQ deficits in patients with fetal alcohol syndrome, effects on IQ have not generally been reported for children with alcohol‐related neurodevelopmental disorder (ARND). This study examined the role of maternal age, MAST, and quality of parenting in moderating the effects of prenatal alcohol exposure on the WISC‐III IQ test in moderate‐to‐heavily exposed children.

Methods: A total of 337 inner‐city African American children whose mothers were recruited prenatally were administered the WISC‐III at 7.5 years. Alcohol exposure was assesed with a timeline follow‐back interview administered at every prenatal clinic visit. Moderating effects of the three risk factors were examined by adding interaction terms to regression analyses and dichotomizing the moderators and performing separate regressions on the two groups.

Results: Prenatal alcohol exposure was related to WISC‐III Freedom from Distractibility but not to Full Scale IQ for the sample as a whole. However, among children born to older mothers, an alcohol effect emerged on Full Scale IQ and five of seven composite IQ scores. Similarly, adverse effects were seen among children of MAST‐positive mothers and children whose parents provided less optimal cognitive stimulation. Each additional ounce of absolute alcohol consumed per day during pregnancy was associated with a 2.9‐point decrease in Full Scale IQ and a 5.6‐point decrement on Freedom from Distractibility.

Conclusions: This study is the first to demonstrate IQ effects among children with ARND born to older and MAST‐positive mothers, particularly in relation to first‐trimester drinking. These findings suggest that there are subgroups of more vulnerable and severely affected children whose intellectual performance is compromised. A moderate‐ to heavy‐drinking mother who has given birth to an unaffected child when she was younger needs to be warned that her risk of having an adversely affected child increases as she grows older.
Ethanol Effects on Dopaminergic “Reward” Neurons in the Ventral Tegmental Area and the Mesolimbic Pathway
Authors: Appel Sarah B. , McBride William J. , Diana Marco , Diamond Ivan , Bonci Antonello , Brodie Mark S.
Published: November 2004

Dopaminergic (DA) neurons in the ventral tegmental area (VTA) provide the DA innervation of the nucleus accumbens. This mesolimbic DA pathway is important for the reinforcing effects of alcohol and plays a central role in alcohol‐related behaviors. This Research Society on Alcoholism symposium included a discussion of the acute and chronic effects of ethanol and ethanol withdrawal on DA VTA neurons. The experiments that were discussed ranged from studies in the freely moving behaving rat and electrophysiological studies in vivo, to electrophysiological studies in brain slices and acutely dissociated DA VTA neurons, to neurochemical studies that explored the cellular basis of ethanol's actions. Because ethanol's effects on this reinforcement pathway are critically important for voluntary intake of alcohol and alcohol addiction, this symposium report may be of interest to both basic science and clinical researchers in the alcohol field. This symposium focused on effects of ethanol on the mesolimbic dopamine pathway, specifically the VTA and the nucleus accumbens. The organizer/co‐chairs were Sarah B. Appel and Mark S. Brodie. The presentations were (1) Introduction, by Mark S. Brodie; (2) Reinforcing Actions of Alcohol in the Ventral Tegmental Area: Intracranial Self‐Administration Studies, by William J. McBride; (3) A Possible Mechanism Mediating the Direct Excitation of Dopaminergic Ventral Tegmental Area Neurons by Ethanol, by Sarah B. Appel; (4) Effect of Chronic Ethanol and Withdrawal on Dopaminergic Ventral Tegmental Area Neurons: In Vivo Electrophysiological Studies, by Marco Diana; (5) Ethanol Induces Protein Kinase A Translocation Into the Nucleus, Cyclic AMP Response Element Binding Protein Phosphorylation, and Increases in Cyclic Adenosine Monophosphate–Dependent Gene Expression, by Ivan Diamond; and (6) Co‐activation of Dopamine D1 and D2 Receptors Is Necessary for Dopamine‐Mediated Increases in Firing Activity in Nucleus Accumbens Neurons, by Antonello Bonci.
On the distribution of elastic forces in disordered structures and materials. I. Computer simulation
Authors: Ngan A. H. W.
Published: November 2004

Randomly structured materials and structures develop distributed internal forces when subjected to external loadings. Using granular packings, and random honeycombs and open–cell foams as prototypic examples, computer simulations were carried out to elucidate the statistical distribution of the internal forces in randomly structured materials. It was found that the sharpness of the force distribution depends critically on the degree of randomness of the structure. In general, the force distributions in these exemplary systems are found to range from the Maxwell–Boltzmann form to a sharply peaked Gaussian form. The results presented here form the basis for the development of a statistical mechanics theory to be presented elsewhere as part II.