Differences In Nutrient Supply Research Articles

Changes in milk production and estimated income over feed cost of group-housed dairy cows when moved between pens

Several studies have shown advantages of feeding cows in groups according to their nutrient requirements. However, there are concerns about losing milk when cows change from a high- to a low-nutrient diet. Data from 1,960 cows from 3 herds were analyzed to assess the impact on milk yield and estimated income over feed cost (IOFC) when moving cows between pens and rations. Pen feed intake and individual body weight and milk yield were recorded daily for 21 d before and 21 d after every pen movement. The data included 2,142 pen movements, and for each movement, milk production was recorded for 21 d before and 21 d after the change. Within farm, group, and cow, milk yield during the 21 d preceding a pen movement was used to predict milk yield for the subsequent 21 d using linear regression. Individual dry matter intake was estimated based on cow performance and diet composition, and then individual IOFC was calculated. Differences between actual and predicted milk yield and IOFC during the 21 d following a movement were determined and contrasted against zero using t-tests. In all 3 farms, every pen movement involved a change from a more expensive ration with more energy and protein than the one fed after the movement. On average, in all cases but one, observed milk yield was lower than the forecasted milk yield had cows not been moved. However, IOFC, on average, was positive in all cases except for 2 pen movements on 2 farms. Reasons for the improved IOFC with lower milk yield were due to a nutrient cost advantage, whereas, when IOFC decreased, differences in nutrient supply and dietary cost were not able to offset differences in milk yield. Moving cows according to milk production level does not result in economic advantages when the unit cost of nutrients is greater in the original than in the receiving ration. However, when the cost and nutrient difference between the diets offset potential losses in milk, forming groups according to production is advantageous.

Early vs late enteral nutrition in pediatric intensive care unit: Barriers, benefits, and complications.

This study aimed to define the existing barriers for early enteral nutrition (EEN) in critically ill children and to analyze the differences in nutrient supply, complications, and outcomes between EEN and late EN (LEN). This is a secondary analysis of a multicenter observational, prospective study including critically ill children receiving EN. Variables analyzed included demographic and anthropometric features, caloric and nutrient supply, outcomes, and complications according to the EN onset. Patients were classified into two groups according to the start of EN: 24-EEN vs EN started after 24 h (24-LEN) and 48-EEN vs EN started after 48 h (48-LEN). Sixty-eight children were enrolled; 22.1% received 24-EEN, and 67.6% received 48-EEN. EN was most frequently delayed in patients older than 12 months, in patients with cardiac disease, and in those requiring mechanical ventilation (MV). Children in the 24-EEN group had shorter duration of MV compared with those in the 24-LEN group (P = 0.04). The 48-EEN group received a higher caloric intake (P = 0.04), reached the caloric target earlier (P < 0.01), and had lower incidence of constipation (P = 0.01) than the 48-LEN group. There was a positive correlation between the time required to reach the maximum caloric intake and the length of pediatric intensive care stay (r = 0.46; P < 0.01). EEN may improve nutrient delivery, reduce time on MV, and prevent constipation in critically ill children. No relevant differences between 24-EEN and 48-EEN were found. Cardiac disease, MV, and age older than 12 months were risk factors associated with LEN.

Evaluation of a Novel Shallow Aggregate Ebb-and-flood Culture System and Transplant Size Effects on Hydroponic Basil Yield

Ornamental bedding plant operations transitioning to leafy greens and herb production must decide whether to invest in new hydroponic equipment or modify existing culture systems for edible crops. In addition, common practices used to increase space-use and production efficiencies during bedding plant production may be modified for hydroponic leafy greens and herbs, such as purchasing large seedlings for transplant. The objective of the first experiment was to evaluate plant growth in a modified and novel shallow aggregate ebb-and-flood (SAEF) system intended for bedding plant growers with an emphasis on comparing yield across four basil (Ocimum basilicum) cultivars grown in the SAEF system to those grown using the traditional nutrient film technique (NFT) and deep water culture (DWC) hydroponic systems. The second experiment objective was to evaluate basil seedling size and the time of transplant to NFT hydroponic systems to determine effects on the final yield. ‘Genovese’ basil seedlings were grown in trays with cell counts of 32, 50, 72, 105, and 162 cells with corresponding root volumes per plant of 98.1, 50.2, 38.5, 19.6, and 16.3 cm3, respectively. Seedlings were transplanted to NFT systems at 14, 21, and 28 days after sowing and were harvested at 35 days. In the first experiment, overall basil shoot fresh and dry weights per plant were intermediate in the SAEF system (90.4 and 8.3 g) compared with the DWC (102.6 and 9.1 g) and NFT (75.8 and 6.6 g) hydroponic systems. In the second experiment, final shoot fresh and dry weight per plant increased as seedling root volume increased from 16.3 cm3 [72.8 and 5.5 g (162-cell tray)] to 98.1 cm3 [148.5 and 12.2 g (32-cell tray)]. Transplanting seedlings at later dates decreased yield across tray size and root volume treatments. Differences in yield between culture systems may have resulted from differences in nutrient supply and availability for plant uptake. Transplant of large seedling plugs to hydroponic culture was not shown to increase space-use efficiency after transplant without compromising yield, likely because root zone factors limited growth during seedling production. Further investigation into maximizing plant growth during seedling production and evaluating the effects of seedling size and transplant practices are needed to determine the potential for increasing space-use and production efficiencies.

Bioavailability of selenium (Se) in cattle population in Sri Lanka based on qualitative determination of glutathione peroxidase (GSH-Px) activities.

Glutathione Peroxidase activity in whole blood is well correlated with the Selenium (Se) levels in cattle hence can be used effectively to assess the supply of Se to farm animals. In this study, Se status of cattle from five different geographic regions of Sri Lanka were assessed based on glutathione peroxidase (GSH-Px) activity. The GSH-Px activity was determined in whole blood samples collected from 80 cattle from 31 different farms in five districts viz. Kandy, Anuradhapura, Batticoloa, Trincomalee and Jaffna using photometric method. Mean GSH-Px activity was found to be 825, 1239, 1039, 849 and 1307μkatL-1 in above districts, respectively while the reference value was considered as 665.4 μkatL-1. Among the studied animals, insufficient Se levels were detected in 50%, 17%, 9%, 27% and 5%, respectively, from above districts. Kruskal Wallis test indicated a significant variation among the sampled locations with respect to the GSH-Px activity (p = 0.001). Selenium content in pasture and water collected from studied locations varied from 6.0 to 554μgkg-1 and < 0.03-1.14μg L-1, respectively. The lower Se levels in feeds recorded from Kandy region infer the lower GSH-Px activity in the animals from the same region. This variability may be due to differences in nutrient supply, age and species of cattle, and lactation stage. Although the assessing method has some limitations, the activity of GSH-Px of the samples indirectly confirms that considerable numbers of cattle from Sri Lanka are with insufficient selenium levels.

Hybrid modeling frameworks of tumor development and treatment.

Tumors are complex multicellular heterogeneous systems comprised of components that interact with and modify one another. Tumor development depends on multiple factors: intrinsic, such as genetic mutations, altered signaling pathways, or variable receptor expression; and extrinsic, such as differences in nutrient supply, crosstalk with stromal or immune cells, or variable composition of the surrounding extracellular matrix. Tumors are also characterized by high cellular heterogeneity and dynamically changing tumor microenvironments. The complexity increases when this multiscale, multicomponent system is perturbed by anticancer treatments. Modeling such complex systems and predicting how tumors will respond to therapies require mathematical models that can handle various types of information and combine diverse theoretical methods on multiple temporal and spatial scales, that is, hybrid models. In this update, we discuss the progress that has been achieved during the last 10 years in the area of the hybrid modeling of tumors. The classical definition of hybrid models refers to the coupling of discrete descriptions of cells with continuous descriptions of microenvironmental factors. To reflect on the direction that the modeling field has taken, we propose extending the definition of hybrid models to include of coupling two or more different mathematical frameworks. Thus, in addition to discussing recent advances in discrete/continuous modeling, we also discuss how these two mathematical descriptions can be coupled with theoretical frameworks of optimal control, optimization, fluid dynamics, game theory, and machine learning. All these methods will be illustrated with applications to tumor development and various anticancer treatments.This article is characterized under:Analytical and Computational Methods > Computational MethodsTranslational, Genomic, and Systems Medicine > Therapeutic MethodsModels of Systems Properties and Processes > Organ, Tissue, and Physiological Models

Controls on organic matter distributions in Eocene Lake Uinta, Utah and Colorado

The Green River Formation deposited in Eocene Lake Uinta in the Uinta and Piceance Basins, Utah and Colorado, contains the largest oil shale resource in the world with an estimated 1.53 trillion barrels of oil in place in the Piceance Basin and 1.32 trillion barrels in the Uinta Basin. The Douglas Creek arch, a slowly subsiding hinge-line between the two basins, created separate deep depocenters, one in each basin with shallow water conditions near the crest of the arch. Lake Uinta was a saline lake throughout its history with a lower saline to hypersaline layer (monimolimnion) and an upper less saline layer (mixolimnion). Most of the organic matter in the Green River Formation was derived primarily from algae that lived in the photic zone of the lake and is very hydrogen-rich and oil-prone. In many modern large and deep lakes, rates of organic matter production are highly variable due to differences in nutrient supply. However, cyclonic circulation often leads to winnowing out of organic and mineral matter in the mixolimnion leading to organic matter and fine-grained mineral matter being deposited in increasing amounts toward hydro-dynamically dead zones in the center of the circulation producing concentric bands of increasing organic matter content. Organic matter transport through the dense, hypersaline monimolimnion may have been facilitated by low density organic matter attaching to more dense clay mineral particles. Most of the oil shale intervals deposited in Lake Uinta display similar patterns in their organic matter distributions, increasing in very regular fashion toward the central areas of the lake’s two depocenters. This concentric feature is particularly prominent in the most laminated oil shale zones. Here, we propose that cyclonic circulation was present in Lake Uinta. Each basin appears to have had its own circulation currents, separated by shallow water conditions near the Douglas Creek arch, and one hydrodynamically dead zone in each basin. Sediment gravity flow processes were also very active in some strata of Lake Uinta, leading to the reworking and re-depositing of sediments. Two general types of sediment gravity flows are recognized: (1) organic-rich sediment gravity flows that reworked and may have concentrated organic-rich material closer to the two deep depocenters, and (2) sandstone- and siltstone-rich organic-poor mass movement deposits that originated on marginal shelves. Mass movements could have been triggered by various natural processes and/or possibly by the movement of dense brines that evolved on marginal shelves and moved along the bottom of the water column toward the deep part of the lake. The uppermost, poorly consolidated sediment layer was incorporated in sediment gravity flows as they moved, and in many cases sediment gravity flows scoured down significantly into the more consolidated underlying sediment producing large rip-up clasts of laminated sediments. Truncation of more than 100 ft occurs at the base of a sequence of sediment gravity flows in one well, indicating a significant incised channel. Coarser-grained sediment gravity flows terminated before reaching the lake’s deepest areas, forming thick concentric buildups of organically lean sediment near the base of the marginal slopes. Intervals dominated by organic-rich fine-grained sediment gravity flows have tightly concentric bands of increasing organic matter toward the deepest parts of the lake and can be organically richer than the richest laminated intervals. There is some evidence that the hydrodynamically quiet zones did not always correspond closely to the deepest areas of the lake, extending in some cases into some shallower areas.

Performance, body fat reserves and plasma metabolites in Brown Swiss dairy cows: Indoor feeding versus pasture-based feeding.

Feeding dairy cows indoors or on pasture affects not only labour, machinery and housing costs, but also animals' performance and metabolism. This study investigates the effects of indoor feeding (IF) with a partial-mixed ration (PMR) versus pasture-based feeding (PF) on milk production, fertility, backfat thickness (BFT), body weight (BW) loss and energy metabolism of Brown Swiss (BS) dairy cows with similar genetic production potential. The IF herd consisted of 13 cows fed a PMR composed of maize and grass silage plus protein concentrate according to each cow's requirements. The PF herd consisted of 14cows offered barn-ventilated hay ad libitum after calving from January until March and grazed on semi-continuous pastures during the vegetation period. The IF cows produced more energy-corrected milk (ECM) per standard lactation (9,407 vs. 5,960kg; p<.01), more milk fat (378 vs. 227kg; p<.01) and milk protein (326 vs. 215kg; p<.01). The calving interval (377 vs. 405days; p<.01) and time empty (86 vs. 118 days; p<.01) were shorter in the PF compared to IF, possibly also due to different selection criteria for maintaining the respective seasonal calving rhythm. The empty body fat loss calculated according to BCS until its nadir was higher in IF cows (IF: 10.4 vs. PF: 4.8 MJ/day; p<.01), but no differences were noted in total body fat loss estimated via BFT (p=.24). However, PF had lower blood glucose concentration at all investigated time points, but no differences occurred in serum non-esterified fatty acid and β-hydroxybutyrate concentrations post-partum. In conclusion, BS cows were equally well suited for the IF with PMR and the PF system investigated here without developing a prominent metabolic load despite differences in nutrient supply. As such, investigated BS dairy cows in our trial seem to have a high capacity for metabolic adaptation to different production systems.

Dissolved N:P ratio changes in the eastern tropical North Atlantic: effect on phytoplankton growth and community structure

Previous bioassays conducted in the oligotrophic Atlantic Ocean identified availability of inorganic nitrogen (N) as the proximate limiting nutrient control of primary production, but additionally displayed a synergistic growth effect of combined N and phosphorus (P) addition. To classify conditions of nutrient limitation of coastal phytoplankton in the tropical ocean, we performed an 11 d nutrient-enrichment experiment with a natural phytoplankton community from shelf waters off northwest Africa in shipboard mesocosms. We used pigment and gene fingerprinting in combination with flow cytometry for classification and quantification of the taxon-specific photoautotrophic response to differences in nutrient supply. The developing primary bloom was dominated by diatoms and was significantly higher in the treatments receiving initial N addition. The combined supply of N and P did not induce a further increase in phytoplankton abundance compared to high N addition alone. A secondary bloom during the course of the experiment again displayed higher primary producer standing stock in the N-fertilized treatments. Bacterial abundance correlated positively with phytoplankton biomass. Dominance of the photoautotrophic assemblage by N-limited diatoms in conjunction with a probable absence of any P-limited phytoplankton species prevented an additive effect of combined N and P addition on total phytoplankton biomass. Furthermore, after nutrient exhaustion, dinitrogen (N-2)-fixing cyanobacteria succeeded the bloom-forming diatoms. Shelf waters in the tropical eastern Atlantic may thus support growth of diazotrophic cyanobacteria such as Trichodesmium sp. subsequent to upwelling pulses.

Nutrient Limitation Governs Staphylococcus aureus Metabolism and Niche Adaptation in the Human Nose

Colonization of the human nose by Staphylococcus aureus in one-third of the population represents a major risk factor for invasive infections. The basis for adaptation of S. aureus to this specific habitat and reasons for the human predisposition to become colonized have remained largely unknown. Human nasal secretions were analyzed by metabolomics and found to contain potential nutrients in rather low amounts. No significant differences were found between S. aureus carriers and non-carriers, indicating that carriage is not associated with individual differences in nutrient supply. A synthetic nasal medium (SNM3) was composed based on the metabolomics data that permits consistent growth of S. aureus isolates. Key genes were expressed in SNM3 in a similar way as in the human nose, indicating that SNM3 represents a suitable surrogate environment for in vitro simulation studies. While the majority of S. aureus strains grew well in SNM3, most of the tested coagulase-negative staphylococci (CoNS) had major problems to multiply in SNM3 supporting the notion that CoNS are less well adapted to the nose and colonize preferentially the human skin. Global gene expression analysis revealed that, during growth in SNM3, S. aureus depends heavily on de novo synthesis of methionine. Accordingly, the methionine-biosynthesis enzyme cysteine-γ-synthase (MetI) was indispensable for growth in SNM3, and the MetI inhibitor DL-propargylglycine inhibited S. aureus growth in SNM3 but not in the presence of methionine. Of note, metI was strongly up-regulated by S. aureus in human noses, and metI mutants were strongly abrogated in their capacity to colonize the noses of cotton rats. These findings indicate that the methionine biosynthetic pathway may include promising antimicrobial targets that have previously remained unrecognized. Hence, exploring the environmental conditions facultative pathogens are exposed to during colonization can be useful for understanding niche adaptation and identifying targets for new antimicrobial strategies.

Relationships among soil moisture, aeration and plant communities in natural and harvested coniferous forests in coastal British Columbia, Canada

Summary1. This study was undertaken to address a curious ecological phenomenon that occurs over extensive areas of northern Vancouver Island, Canada. Slow tree growth and symptoms of nutrient deficiencies appear within 10 years of harvesting old‐growth cedar‐hemlock (CH) forests, but do not occur on adjacent hemlock‐fir (HA) stands. We investigate the underlying causes of distinct differences in productivity and fertility of the two ecosystems.2. We hypothesized that the differences in nutrient supply and tree growth arise from small, but ecologically significant, differences in soil moisture with attendant effects on redox potential (Eh), aeration, soil C stores and plant species distribution. Our field studies determined (i) whether neighbouring CH and HA forests differ in soil moisture and aeration, (ii) whether soil carbon stores differ among CH and HA forests, (iii) whether plant community composition in the two forest types is related to soil moisture and aeration and (iv) the impact of harvesting CH and HA forests on moisture and aeration conditions.3. As hypothesized, soils in CH forests were wetter and less aerated, and had shallower aerated depth and higher frequency of anaerobic conditions compared with HA forests. About 43% of the samples taken from CH forests had average redox values &lt;+300 mV, a threshold below which anaerobic conditions develop and root growth is impeded. Soil carbon stores and rates of decomposition of cellulose did not differ among the forest types. Soil aeration explained 25% of the variability in species composition of plant communities.4. The two forest types responded differently to clear‐cut harvesting, and there were indications that clear‐cut harvesting could trigger reductions in soil aeration in some HA forest soils which could lead to paludification and a decline in site productivity of these ecosystems.5. Synthesis.Our findings confirmed that these ecosystems bracket a critical biological threshold below which low soil oxygen availability caused by excessive moisture becomes limiting for biological processes. Recognition of this redox threshold and its ecological implications could contribute to improved ability to manage ecosystems which may be near this threshold or become so in a changing climate.

Surprising variety in energy metabolism within Trypanosomatidae

The metabolism of Trypanosomatidae differs significantly between distinct species and can even be completely different between various life-cycle stages of the same species. It has been proposed that differences in energy metabolism are related to differences in nutrient supply in the environments of the various trypanosomatids. However, the literature shows that availability of substrates does not dictate the type of energy metabolism of trypanosomatids, as Trypanosoma theileri, Trypanosoma lewisi and African trypanosomes all live in the bloodstream of their mammalian host, but have surprisingly large differences in metabolism. Furthermore, in trypanosomatids no obvious relationship exists between energy metabolism and phylogeny or mode of transmission. We provide an overview of the metabolic capacities in the energy metabolism of distinct trypanosomatids, and suggest that these can be divided into four different metabolic categories of increasing complexity.

Phenotypic Characterization of Indigenous Tswana Goats and Sheep Breeds in Botswana: Continuous Traits

The majority of Tswana sheep and goats in Botswana are indigenous. These animals provide income, employment and food security to the resource-poor farmers. Limited characterization of these species has been done, resulting in poor efforts to fully exploit and conserve them. The objective of this study was to phenotyically characterize indigenous sheep and goats countrywide. Measurements were collected from 2783 goats and 1282 sheep kept by traditional farmers, covering nearly all the districts of Botswana. In each district a total of 15 farmers with sheep and goats were selected randomly and records were taken on 4-12 animals per farm, depending on average district flock size. Traits recorded for each animal were body length, body weight, ear length, heart girth, height at withers, hip width, neck length, rump height, shoulder width, tail length (goats only) and horn length. Age (estimated from dentition) and sex of the animals were also recorded and vegetation type was noted. The data were analysed using the general linear model procedure in Statistical Analysis System. Prior to analyses, a main effects model of sex, age and vegetation type was fitted. Later, two types of analyses were done: (i) within a vegetation type fitting sex and age and their interaction, and (ii) within sex fitting age and vegetation type and their interaction. Least-squares means were separated using Student's t-test. Sex, age and vegetation significantly (p<0.05) affected the magnitude of traits. Phenotypic body measurements of castrates were generally higher than in both females and entire males, which were similar. The body measurements of younger animals were less than those of older age groups since the former were still growing compared to the latter. Different vegetation types promoted different body measurements, which should be expected due to differences in nutrient supply from different vegetation types. The indigenous breeds of sheep and goats can be classified as medium-size breeds. The breeds should be conserved since they are well suited to the harsh environment of Botswana where drought and livestock diseases are ever present. Efforts should be undertaken to characterize them genetically and increase their productivity.

Rumen Acid Production from Dairy Feeds. 2. Effects of Diets Based on Corn Silage on Feed Intake and Milk Yield

A new approach to evaluating feeds has been developed based on in vitro estimates of rumen acid load (acidogenicity value). The present work was conducted to establish effects of rumen acid load on dry matter intake and milk production of early-lactation dairy cows fed corn silage-based diets. The effects of diet acidogenicity were investigated independently of ingredient composition using a series of isoenergetic and isonitrogenous concentrates that used different raw materials to achieve the same acidogenicity value. Six concentrates were formulated to be fed at 7kg/d, and two at 10kg/d. Continuous culture equipment, which had been modified to control and record infusions of acid and alkali to maintain pH in the range 6.2 to 6.3, confirmed the ranking of concentrates based on the in vitro technique. The concentrates were offered to dairy cows in early lactation with corn silage available ad libitum. Forage intake declined with increasing concentrate acidogenicity, particularly at the higher level of concentrate feeding. However, concentrate acidogenicity had a significant negative effect on dry matter intake even at 7kg/d. Feed intakes were similar for concentrates that were formulated to be isoacidogenic, but using different raw materials. There were only small and inconsistent effects of concentrate acidogenicity value on milk yield and milk fat percentage, while milk protein percentage was higher with the high AV concentrates. Effects on milk composition likely reflect differences in nutrient supply and there was no evidence for effects of rumen acid load per se on milk composition.

Effects of Altering Energy and Protein Supply to Dairy Cows During the Dry Period. 1. Intake, Body Condition, and Milk Production

We used 48 Holstein-Friesian cows to investigate the effects of altering energy and protein supply to dry cows. Cows were fed one of three diets for 6 wk prior to parturition: (a) a 60:40 (DM basis) mixture of grass silage with barley straw ad libitum; (b) grass silage ad libitum; or (c) 0.5 kg/d of prairie meal with grass silage ad libitum. The standard lactation diet was a flat-rate allocation of concentrates and grass silage ad libitum. We evaluated dry-period diets using four dry fistulated cows; rumen pH remained high (mean = 6.6) and ammonia concentrations followed N intake. The inclusion of straw reduced apparent ruminal digestion of OM, N, and NDF as well as microbial protein yield, though microbial yield per unit of OM apparently digested in the rumen remained unchanged. Voluntary intake of forage was reduced by the inclusion of straw, while the inclusion of prairie meal had little effect. The decline in intake as calving approached was lower with the silage and straw mix diet. There were large differences in the BW change over the final 5 wk of the dry period, although the opposite effect was seen in early lactation, and differences in BW and body condition score were small by lactation wk 22. Despite the substantial differences in nutrient supply and effects on body reserves, there was little effect of dry-period diet on subsequent performance. Lower forage intakes and yields of protein and lactose were confined to the first month of lactation for cows previously offered straw.

Biomass partitioning, architecture and turnover of six herbaceous species from habitats with different nutrient supply

Three grasses (Holcus lanatus, Anthoxanthum odoratum and Festuca ovina) and three herbs (Rumex obtusifolius, Plantago lanceolata and Hieracium pilosella) were grown in a greenhouse at 3 nutrient levels in order to evaluate plant allocation, architecture and biomass turnover in relation to fertility level of their habitats. Four harvests were done at intervals of 4 weeks. Various plant traits related to biomass partitioning, plant architecture, biomass turnover and performance were determined. Differences in nutrient supply induced a strong functional response in the species shoot:root allocation, but architecture and turnover showed little or no response. Architectural parameters like specific leaf area and specific root length, however, in general decreased during plant development. Species from more nutrient-rich successional stages were characterized by a larger specific leaf area and longer specific shoot height (height/shoot biomass), resulting in a higher RGR and total biomass in all nutrient conditions. There was no evidence that species from nutrient-poor environments had a longer specific root length or any other superior growth characteristic. The only advantage displayed by these species was a lower leaf turnover when expressed as the fraction of dead leaves and a shorter specific shoot height (SSH) which might prevent herbivory and mowing losses. The dead leaf fraction, which is a good indicator for biomass and nutrient loss, appeared to be not only determined by the leaf longevity, but was also found to be directly related to the RGR of the species. This new fact might explain the slow relative growth rates in species from a nutrient-poor habitat and should be considered in future discussions about turnover.

Effect of genotype and nutrition on calpastatin inhibitory activity and mRNA abundance in milk-fed lambs

Muscle proteolysis is controlled by a wide range of enzyme systems. The reported effects of the calcium dependent proteinases (calpain I and II) and its specific inhibitor (calpastatin) on myofibrillar structure, has led to the speculation that this system may have a pivotal role in regulating protein turnover and muscle growth. The present study highlights the possibility of protein degradation being subject to genetic variation. The relationship between genotype, level of nutrition, muscle protein turnover and the calpain system in young milk-fed lambs was assessed. Male lambs which had been selected for 10 generations for high (W+) and low (W-) weight at weaning were used in the study. Lambs were removed from their mothers 4 days after birth and surgically fitted with abomasal catheters and infused with reconstituted milk replacer at a high or a low rate. At 8 weeks of age, measurements of muscle protein gain, synthesis and degradation were performed, the animals were slaughtered and samples rapidly removed for subsequent chemical analysis. The liveweight gain and weight of the m vastus lateralis was reflected ( P < 0.001) in the designed differences in nutrient supply. The weight of the m vastus lateralis was greater ( P < 0.01) in the W+ compared to the W- lambs. The rate of protein synthesis and calculated degradation were greater ( P < 0.05) in W+ than W- lambs. Calpain I and II and calpastatin activity were not significantly altered by genotype or nutrition. Calpastatin mRNA abundance increased significantly ( P < 0.05) between 1 and 8 weeks of age. Regression analysis revealed genotype-specific responses with respect to calpastatin activity and mRNA abundance. The results suggest that in sheep lines genetically divergent for growth potential, differences in the rate of protein gain were associated with alterations in muscle protein degradation and its sensitivity to nutrient supply. The differences may in part be explained by differences in the calpain system, including the specific inhibitor calpastatin between the genotypes.

Biogeography of planktonic foraminifera and regional carbon isotope variations: productivity and water masses in late Cretaceous Europe

The first appearances of species of Marginotruncana (planktonic foraminifera) are found stratigraphically earlier in Boreal northwestern Germany than in the Tethys. Helvetoglobotruncana helvetica (Bolli) is rare in northwestern Germany and common in the Tethys. Its stratigraphic range is probably comparable between both areas. The biogeographic patterns are discussed with respect to influences of water depths (based on isotope evidence for the depth distribution of species of Hedbergella, Praeglobotruncana, and Rotalipora) and water temperatures. The regional variation of δ 13C values of Cenomanian-Turonian pelagic carbonates was mapped for the European epicontinental basins and the southern European shelf (Helvetic zone of the Alps). The highest δ 13C values (up to 5‰) were found in northwestern Germany and the eastern North Sea and are coincident with an upwelling zone numerically predicted by three independent climate models. Intermediate values in France and England (2–4‰) correspond to predicted weak upwelling. Lowest values occur in the Alpine Helvetic zone and the south German Regensburg area (1–2‰) and coincide with predicted absence of upwelling. The δ 13C values are interpreted as indicators of increased biogenic productivity in the upwelling zone. Semiquantitative nannofossil data suggest abundance patterns influenced by latitude, neritic-oceanic gradients, and productivity. Observations agree with east-to-west wind-driven surface-current systems. Regional differences in nutrient supply and, subsequently, different primary productivity could have been a major factor controlling the evolution and the biogeographic distribution of planktonic foraminifera in Cenomanian-Turonian Europe.

Nutrient flux and the evolutionary explosion across the Precambrian‐Cambrian boundary interval

The “Cambrian explosion” in biosphere diversity was accompanied by major changes in sea level, the carbon cycle and phosphorus deposition. Carbon isotope excursions can be traced across Gondwana from China to Iran, as well as onto the Siberian Platform, and into Australia and Morocco. These isotopic excursions were contemporaneous with episodes of evaporite deposition and hydrocarbon burial in the Persian Gulf, Pakistan and Siberia, and followed by widespread salinity stratification. It appears likely that nutrient supply was affected by these changes. Differences in nutrient supply may explain the contrasting diversity and biomineralization patterns of phosphophilic invertebrates and oligotrophic archaeocyathan sponges through the early Cambrian.

Vegetational gradients in relation to environmental conditions in northwestern European mires

Floristically characterized gradients related to (i) mire surface microtopography, (ii) marginal versus central areas, (iii) ombrotrophy and minerotrophy ("poor and rich mires"), and (iv) distance from the sea can be recognized in the mire vegetation of northwestern Europe. Along these gradients variation occurs in (i) oscillations in the water level, (ii) origin and flow of water, and (iii) supply of minerals. These conditions influence the decay processes and the resulting peat accumulation rate, pH, mineral nutrient supply, and productivity. The differences between marginal and open areas result from differences in nutrient supply (N,P,K), while the differences between "poor and rich" mires are due to differences in the reactions of the peat. In Sphagnum-dominated vegetation, most floristic variation results from effects of differences in peat accumulation rates. Climatic conditions, other than atmospheric supply of minerals, are most important in establishing the regional floristic differences in the bog vegetation.

Anatomical Responses of Tomato Stems to Variations in the Macronutrient Anion Supply

1. An inbred strain of Bonny Best tomatoes was grown in sand culture. The effects of forty-four nutrient solutions varying in the relative proportions of macronutrient anions were studied in relation to the anatomy of plant stems. Measurements of stem diameter and the actual area of each of the component tissue systems were recorded. The data were reduced and analyzed by statistical methods. 2. Great differences in stem diameter and the actual area of each of the component tissue systems could be correlated with differences in nutrient supply. 3. Differences in the relative proportion of phloem, xylem, and pith in stem sections were correlated with differences in nutrient supply. No differences were found in the relative amount of cortex. 4. Cellular differences in pith parenchyma, xylem vessels and fibers, internal and external phloem, internal and external pericyclic fibers, and cortical cells are described and correlated with nutrient supply. 5. Differences in the anatomy of the tomato stems are significantly correlated with characteristics used as criteria of vegetative growth and fruitfulness.