Genetics of early conception and its relationship to growth traits in red deer (Cervus elaphus)

The genetics of early conception success and live-animal growth were studied in five herds of red deer in New Zealand. Conception date (CD) was used as the criterion of success in seasonally mated hinds, with 2493 mating records available. Liveweights analysed were weaning weight, yearling weight, 15-month weight and mature weight (hinds only). CD and liveweights were analysed using restricted maximum likelihood procedures with an animal model, including all available pedigree records. Under the management conditions applied, CD had a phenotypic standard deviation of 7.9 days, a repeatability across years of 0.29 ± 0.03 and a direct (univariate) heritability of 0.20 ± 0.06. Regression procedures using DNA markers to adjust the data for genetic differences resulting from an animal’s ancestral region of origin (mainly western vs eastern European) had little effect on the parameter estimates above. Direct heritability estimates for the four weight traits were 0.38 ± 0.03, 0.49 ± 0.02, 0.48 ± 0.04 and 0.46 ± 0.04, respectively, while the genetic correlations between CD and these traits (e.g. using 1763 paired records of CD with yearling weight) were –0.24 ± 0.11, –0.24 ± 0.09, –0.16 ± 0.10 and –0.04 ± 0.09, respectively. Selection for earlier CD would be successful and compatible with selection for higher juvenile weights.

Striated myogenesis and peristalsis in the fetal murine esophagus occur without cell migration or interstitial cells of Cajal

Esophageal striated myogenesis progresses differently from appendicular myogenesis, but the mechanism underlying this process is incompletely understood. Early theories of transdifferentiation of smooth muscle into striated muscle are not supported by transgenic fate-mapping experiments; however, the origin of esophageal striated muscle remains unknown. To better define the process of striated myogenesis, we examined myogenesis in murine fetal cultured esophageal whole-organ explants. Embryonic day 14.5 (E14.5) esophagi maintained a functional contractile phenotype for up to 7 days in culture. Striated myogenesis, as evidenced by myogenin expression, proceeded in a craniocaudal direction along the length of the esophagus. Esophageal length did not change during this process. Complete, but not partial, mechanical disruption of the rostral esophagus inhibited myogenesis distally. Addition of fibroblast growth factor-2 (FGF-2) to the culture media failed to inhibit striated myogenesis, but attenuated smooth muscle actin expression and reduced peristaltic activity. Inhibition of c-kit failed to inhibit peristalsis. These results suggest that striated myogenic precursors are resident along the entire length of the esophagus by day 14.5 and do not migrate along the esophagus after E14.5. Induction of myogenesis craniocaudally appears to require physical continuity of the esophagus and is not inhibited by FGF-2. Finally, peristalsis in E14.5 esophagi appears not to be regulated by interstitial cells of Cajal.

Verification of selective DNA pooling methodology through identification and estimation of the DGAT1 effect

The discovery of markers linked to genes that are responsible for traits of interest to the dairy industry might prove useful because they could aid in selection and breeding decisions. We have developed a selective DNA pooling methodology to allow us to efficiently screen the bovine genome in order to find genes responsible for production traits. Using markers on chromosome 14 as a test case, we identified a gene (DGAT1) previously known to affect three traits (fat yield, protein yield and total milk yield). Furthermore, we predicted similar effects to those previously shown for DGAT1 in a New Zealand Holstein-Friesian herd. Additionally, we showed a low error rate (1.6%) for the pooling procedure. Hence we are confident that we can apply this procedure to an entire genome scan in the search for quantitative trait loci (QTL).

Major histocompatibility antigen expression on the bovine placenta: its relationship to abnormal pregnancies and retained placenta

In viviparous animals, regulation of expression of major histocompatibility complex (MHC) class I antigens by the trophoblast cells, which constitute the outermost layer of the placenta, seems to be critical for maternal immunological acceptance of an allogeneic fetus. Cattle are unusual in this regard, since the bovine trophoblast cells, in specific regions of the uterine/placental interface, normally express MHC class I antigens during the third trimester of gestation. This expression appears to be biologically relevant as MHC class I compatibility between a cow and her fetus has been associated with an increased incidence of placental retention. We have found significant differences in lymphocyte populations, cytokine production, and trophoblast cell apoptosis in the placentomes of MHC-compatible and -incompatible pregnancies at parturition. This suggests that maternal immunological recognition of fetal MHC class I proteins triggers an immune/inflammatory response that contributes to placental separation at parturition in cattle. Early in pregnancy, a complete shutdown of MHC class I expression by trophoblast cells appears to be critical for normal placental development and fetal survival. In bovine somatic cell nuclear transfer (SCNT) pregnancies, there is an extremely high rate of fetal loss between days 30 and 90 of pregnancy. We have shown that in bovine SCNT pregnancies, between days 34 and 63 of gestation, there is both abnormal expression of MHC class I antigens by trophoblast cells and an abnormal accumulation of lymphocytes within the uterine stroma. Consequently, it is likely that activation of the maternal mucosal immune system, within the uterus at the same time when placentomes are being established, interferes with the process of placentome development and leads to immune-mediated abortion. Our data suggest that bovine MHC-compatible pregnancies provide a unique model for studying regulation of the uterine immune system, as well as immune-mediated placental rejection.

Characterization of trophoblast cell populations by lectin histochemistry in canine placenta during development

The aim of this study was to identify and characterize populations of trophoblast cells in canine placenta during different stages of fetal development using lectin histochemistry. Dogs have endotheliochorial placentation and trophoblast cell invasion continues after chorioallantois villous penetration early in pregnancy, leading to formation of a labyrinth. Specialized subpopulations of cells differentiate, such as syncytial trophoblast that invades the maternal epithelium early in placentation and surrounds and forms intimate cuffs around maternal blood vessels. Marginal haematomata, which are lined by specialized phagocytic cytotrophoblast cells, form by mid-gestation. Invasive 'extravillous' cells advance into and remodel maternal endometrial tissues further. Placentas and attached uterine tissues were collected and sampled from six bitches at mid-gestation (days 31-33 of gestation) and 12 females in late gestation (day 42-term) for characterization of these tissues and identification of other populations of trophoblast cells. Uterine tissues from nonpregnant bitches were also collected at oestrus (n = 2) and during the luteal phase (n = 1). In histochemical studies, two of six biotinylated lectins that were tested stained cytotrophoblast and syncytial trophoblast cell populations differentially. Arachis hypogaea agglutinin (PNA) was specific for cytotrophoblasts in placental tissue lining villi and cytotrophoblastic cells with phagocytic or absorptive phenotypes in the necrotic zone at mid-gestation. In late gestation, cytotrophoblast cells with an absorptive phenotype at the interface between the labyrinth and lacunar glandular chambers were stained with PNA. Staining of other cells was minimal, with the exception of deep endometrial glands. Lectin binding using Maclura pomifera agglutinin (MPL) specifically stained the same cells as PNA and the population of invasive syncytial trophoblast cells remodelling maternal blood vessels and small maternal vessels at the materno-fetal interface, as well as trophoblast cells within necrotic zones at mid-gestation. Both lectins were positive for phagocytic cytotrophoblast cells lining the haematophagus organs. The results of this study demonstrate that lectin histochemistry is a useful tool for staining subpopulations of cytotrophoblast and syncytial trophoblast cells.

A genome-wide scan of 1842 DNA markers for allelic associations with general cognitive ability: a five-stage design using DNA pooling and extreme selected groups

All measures of cognitive processes correlate moderately at the phenotypic level and correlate substantially at the genetic level. General cognitive ability (g) refers to what diverse cognitive processes have in common. Our goal is to identify quantitative trait loci (QTLs) associated with high g compared with average g. In order to detect QTLs of small effect size, we used extreme selected samples and a five-stage design with nominal alpha levels that permit false positive results in early stages but remove false positives in later stages. As a first step toward a systematic genome scan for allelic association, we used DNA pooling to screen 1842 simple sequence repeat (SSR) markers approximately evenly spaced at 2 cM throughout the genome in a five-stage design: (1) case-control DNA pooling (101 cases with mean IQ of 136 and 101 controls with mean IQ of 100), (2) case-control DNA pooling (96 cases with IQ > 160 and 100 controls with mean IQ of 102), (3) individual genotyping of Stage 1 sample, (4) individual genotyping of Stage 2 sample, (5) transmission disequilibrium test (TDT; 196 parent-child trios for offspring with IQ > 160). The over all Type I error rate is 0.000125, which robustly protects against false positive results. The numbers of markers surviving each stage using a conservative allele-specific directional test were 108, 6, 4, 2, and 0, respectively, for the five stages. A genomic control test using DNA pooling suggested that the failure to replicate the positive case-control results in the TDT analysis was not due to ethnic stratification. Several markers that were close to significance at all stages are being investigated further. Relying on indirect association based on linkage disequilibrium between markers and QTLs means that 100,000 markers may be needed to exclude QTL associations. Because power drops off precipitously for indirect association approaches when a marker is not close to the QTL, we are not planning to genotype additional SSR markers. Instead we are using the same design to screen markers such as cSNPs and SNPs in regulatory regions that are likely to include functional polymorphisms in which the marker can be presumed to be the QTL.

No association between apolipoprotein E polymorphisms and general cognitive ability in children

In this work we explored the hypothesis that variation in the gene encoding apolipoprotein E (ApoE) is a factor modifying general cognitive ability (g). A case control sample of 101 high g and 101 average g children was scored for ApoE genotypes and two variants in the transcriptional regulatory region of the gene (Th1/E47cs and -491 AT). No evidence of association between these polymorphisms and g was found. We conclude that variation at these loci is not a factor with a measurable impact on general cognitive ability in the healthy population.

Deficient iNOS in inflammatory bowel disease intestinal microvascular endothelial cells results in increased leukocyte adhesion

Microvascular endothelial cells play a key role in inflammation by undergoing activation and recruiting circulating immune cells into tissues and foci of inflammation, an early and rate-limiting step in the inflammatory process. We have previously [Binion et al., Gastroenterology112:1898-1907, 1997] shown that human intestinal microvascular endothelial cells (HIMEC) isolated from surgically resected inflammatory bowel disease (IBD) patient tissue demonstrate significantly increased leukocyte binding in vitro compared to normal HIMEC. Our studies [Binion et al., Am. J. Physiol.275 (Gastrointest. Liver Physiol. 38):G592-G603, 1998] have also demonstrated that nitric oxide (NO) production by inducible nitric oxide synthase (iNOS) normally plays a key role in downregulating HIMEC activation and leukocyte adhesion. Using primary cultures of HIMEC derived from normal and IBD patient tissues, we sought to determine whether alterations in iNOS-derived NO production underlies leukocyte hyperadhesion in IBD. Both nonselective (N(G)-monomethyl-L-arginine) and specific (N-Iminoethyl-L-lysine) inhibitors of iNOS significantly increased leukocyte binding by normal HIMEC activated with cytokines and lipopolysaccharide (LPS), but had no effect on leukocyte adhesion by similarly activated IBD HIMEC. When compared to normal HIMEC, IBD endothelial cells had significantly decreased levels of iNOS mRNA, protein, and NO production following activation. Addition of exogenous NO by co-culture with normal HIMEC or by pharmacologic delivery with the long-acting NO donor detaNONOate restored a normal leukocyte binding pattern in the IBD HIMEC. These data suggest that loss of iNOS expression is a feature of chronically inflamed microvascular endothelial cells, which leads to enhanced leukocyte binding, potentially contributing to chronic, destructive inflammation in IBD.

Numerical densities of myonuclei and satellite cells in muscle fiber types in the aging human thyroarytenoid muscle: an immunohistochemical and stereological study using confocal laser scanning microscopy

OBJECTIVE

This study determines the role of changes in numerical densities of myonuclei and satellite cells in age-related remodeling of the thyroarytenoid muscle (TA).

DESIGN

Changes in numerical densities (N(V)) and ratios (N(N)) of myonuclei and satellite cells were estimated for the entire TA by use of stereological techniques.

RESULTS

There was no age-related change or difference between fiber types for N(V myonucleus, fiber), but N(V myonucleus, fiber) increased with decreasing fiber diameter. There was a trend toward a decrease in N(V satellite cell, fiber) and a decrease in N(N satellite cell, myonucleus). N(V satellite cell, fiber) was higher for type 1 than for type 2 fibers, and type 1 satellite cells increased disproportionately with increasing total satellite cell numerical density.

CONCLUSION

Decreased satellite cell proliferation may contribute to age-related fiber loss and atrophy in the TA.

SIGNIFICANCE

Therapeutic techniques based on activation of satellite cells may block age-related fiber loss and atrophy in the TA.

The bovine placenta before and after birth: placental development and function in health and disease

This paper reviews bovine placental development, anatomy (microscopic and gross), nomenclature and classification. The paper focuses on the biology of those specialized cells that arise from the outermost layer of very early embryos, the trophoblast cells, and on placental macrophages, cells that play a key role in fetal/placental defense. Data is presented from an immunohistochemical quantitative study that characterizes the ontogeny of placental macrophages using placental tissues from 21 cows (sampled from 4 months of pregnancy through the post partum period). Understanding of bovine placental development is essential for veterinarians, pathologists, diagnosticians and researchers. Lesions of diagnostic significance can be recognized for many economically important infectious abortifacient diseases, and there is growing evidence that pregnancy failure of cloned calves is due in part to unexplained placental failure. Placentology and placental pathology are becoming of increasing importance.

Temporal and regional regulation of major histocompatibility complex class I expression at the bovine uterine/placental interface

In most mammals trophoblast cells do not express major histocompatibility complex (MHC) antigens. This probably protects the placenta from immune attack. We have used immunohistochemistry to study the ontogeny of MHC class I expression by bovine trophoblast and endometrial epithelial cells. The interplacentomal, placentomal arcade and placentomal villous/crypt regions were studied. In the interplacentomal region a substantial proportion of trophoblast cells were class I positive from the sixth month on and about half of the endometrial epithelium was class I positive throughout pregnancy. In the arcade region trophoblast class I expression was first observed in the sixth month, increased slowly and peaked at term. Here there was no endometrial epithelial class I expression until term and then only a small percentage of cells were positive. In contrast, in the placentomal villous/crypt region both trophoblast and endometrial epithelium were class I negative throughout gestation. This study shows that cattle have extensive trophoblast class I expression. Moreover class I expression on placentomal, cryptal endometrial epithelium is shut down. Because binucleate trophoblast cells migrate and fuse with endometrial epithelial cells, total shut down of class I expression in areas of intimate interdigitation may be critical for avoidance of immunological rejection.

Age-related changes in muscle fiber types in the human thyroarytenoid muscle: an immunohistochemical and stereological study using confocal laser scanning microscopy

A decline in motor performance contributes to laryngeal dysfunction in the elderly, but the pathogenetic mechanisms are unknown. Quantitative 3-dimensional, age-related changes in the muscle fiber content of the human thyroarytenoid muscle were estimated from geometric probability (stereology) by use of a technique that provided a statistically unbiased sample of all possible section orientations and locations in the entire muscle volume. There was a preferential 27% age-related loss in the length density (L(V type, muscle)) of type 1 (slow) fibers in contrast to the selective type 2 (fast) fiber loss typical of aging limb muscles. In type 2 fibers there was no significant loss in the L(V), but there was an age-related decrease (P < 0.05) in the surface density (S(V type, muscle)) and an increase (P < 0.05) in the atrophy factor, an index of the content of very small, atrophic fibers. There was also an age-related increase in the length fraction (L(L type, all fibers)) of muscle fibers that coexpress both fast and slow myosin heavy-chain isoforms (P < 0.05). These findings demonstrate a type-specific fiber loss and atrophy that differs from that in aging limb muscles and an age-related increase in motor unit remodeling.

DNA pooling identifies QTLs on chromosome 4 for general cognitive ability in children

General cognitive ability (g), which is related to many aspects of brain functioning, is one of the most heritable traits in neuroscience. Similarly to other heritable quantitatively distributed traits, genetic influence on g is likely to be due to the combined action of many genes of small effect [quantitative trait loci (QTLs)], perhaps several on each chromosome. We used DNA pooling for the first time to search a chromosome systematically with a dense map of DNA markers for allelic associations with g. We screened 147 markers on chromosome 4 such that 85% of the chromosome were estimated to be within 1 cM of a marker. Comparing pooled DNA from 51 children of high g and from 51 controls of average g, 11 significant QTL associations emerged. The association with three of these 11 markers ( D4S2943, MSX1 and D4S1607 ) replicated using DNA pooling in independent samples of 50 children of extremely high g and 50 controls. Furthermore, all three associations were confirmed when each individual was genotyped separately ( D4S2943, P = 0. 00045; MSX1, P = 0.011; D4S1607, P = 0.019). Identifying specific genes responsible for such QTL associations will open new windows in cognitive neuroscience through which to observe pathways between genes and learning and memory.

DNA pooling and dense marker maps: a systematic search for genes for cognitive ability

Pooling DNA from subjects within a group and comparing the pooled DNA across groups for a dense map of DNA markers offers a solution to the conundrum that linkage is systematic but not powerful whereas allelic association is powerful but not systematic. We used DNA pooling to screen 66 markers on chromosome 22 in original and replication samples of children of high general cognitive ability (g) and controls of average g. Although none of these markers survived our three-stage screening design (original pooling, replication pooling, individual genotyping), the results of DNA pooling were largely confirmed by individual genotyping. We can therefore exclude associations of major effect size on chromosome 22 for g, a key variable for cognitive neuroscience research on learning and memory.

Single locus microsatellites isolated using 5' anchored PCR

Microsatellites are widely used as genetic markers because they are co-dominant, multiallelic, easily scored and highly polymorphic. A major drawback of microsatellite markers is the time and cost required to characterise them. We have developed a novel technique to reduce this cost by producing a microsatellite-rich PCR profile from genomic DNA which was cloned to yield a genomic library enriched for microsatellites. Sequence data and subsequent allele scoring within pedigrees revealed that these microsatellites retained their original repeat length and segregated normally. This technique permits genomic amplification with only one specific primer. Together with enrichment, the savings in primer costs reduces the cost of microsatellite characterisation considerably.

Structure and dynamics of melittin in lysomyristoyl phosphatidylcholine micelles determined by nuclear magnetic resonance

Mixed micelles of the 26-residue, lytic peptide melittin (MLT) and 1-myristoyl-2-hydroxyl-sn-glycero-3-phosphocholine (MMPC) in aqueous solution at 25 degrees C were investigated by (13)C- and (31)P-NMR spectroscopy. (13)C alpha chemical shifts of isotopically labeled synthetic MLT revealed that MLT in the micelle is predominantly alpha-helical and that the peptide secondary structure is stable from pH 4 to pH 11. Although the helical transformation of MLT as determined from NMR is evident at lipid:peptide molar ratios as low as 1:2, tryptophan fluorescence measurements demonstrate that well-defined micellar complexes do not predominate until lipid:peptide ratios exceed 30:1. (31)P linewidth measurements indicate that the interaction between phosphate ions in solution and cationic groups on MLT is pH dependent, and that the phosphoryl group of MMPC senses a constant charge, most likely +2, on MLT from pH 4 to pH 10. (13)C-NMR relaxation data, analyzed using the model-free formalism, show that the peptide backbone of MLT is partially, but not completely, immobilized in the mixed micelles. Specifically, order parameters (S(2)) of C alpha-H vectors averaged 0.7 and were somewhat larger for residues in the N-terminal half of the molecule. The amino terminal glycine had essentially the same range of motion as the backbone carbons. Likewise, order parameters for the trp side chain were similar to those found for the peptide C alpha moieties, as was verified by trp fluorescence anisotropy decay data. In contrast, the motion of the lysine side chains was less restricted, the average S(2) values for the C epsilon-H vectors being 0.19, 0.30, and 0.44 for lys-7, 21, and 23, respectively, for MLT in the mixed micelles. Values of the effective correlation time of the local motion tau e were in the motional narrowing limit and usually longer for side-chain atoms than for those in the backbone. The dynamics were independent of pH from pH 4 to pH 9, but at pH 11 the correlation time for the rotational motion of the mixed micelles as a whole increased from 10 ns to 16 ns, and S(2) for the lys side chains increased. Overall it appears that the MLT helix lies near the surface of the micelle at low to neutral pH, but at higher pH its orientation changes, accompanied by deeper penetration of the lysine side chains into the micelle interior. It is apparent, however, that the MLT-lipid interaction is not dependent on deprotonation of any of the titratable cationic groups in the peptide in the pH 4-10 range, and that there is substantial backbone and side-chain mobility in micelle-bound MLT.

Survival and spread of the endophyte Stagonospora pteridiicola in Pteridium aquilinum, other ferns and some flowering plants

Pteridium aquilinum (L.) Kuhn was sampled for colonization by Stagonospora pteridiicola in Great Britain, Hungary and Australia. British samples gave the highest incidence of 68% during September and 12% at the beginning of the growing season. Hungarian samples showed a similar frequency. The fungus was not found in Australian bracken. Five field-collected fern species other than bracken did not contain the fungus in May when bracken already had a colonisation frequency of 12% in the pinnules. Sampling after the bracken had died in November demonstrated that the fungus had continued growth as a saprobe. Glasshouse-grown bracken sprayed with a spore suspension showed 96% colonization after 21 d, whereas four fern species and five flowering plants, similarly treated, gave colonization frequencies of 0-3%. Other glasshouse-grown bracken, similarly sprayed, showed that colonization declined over 5 months from 75% to 40%, and that the fungus showed little spread into fresh unsprayed growth on these plants. The possible species specificity of the fungus is discussed.

Fungal endophytes from the leaves and twigs of Quercus ilex L. from England, Majorca and Switzerland

Leaves of Quercus ilex taken from sites in England, Majorca and Switzerland have been studied to detect the influence of the geographic position of the host within and outside its native range on the composition of its endophytic fungal assemblages. Samples of stem tissue of Q. ilex collected from the Swiss trees were also studied to confirm tissue-specific differences. Sixty different fungal taxa were isolated, but only 28 were frequent. Of the total number of isolates from the leaves from the Swiss, British and Spanish sites 87%, 31% and 63%, respectively, were coelomycetes. Four species of Phomopsis, which includes Phyllosticta ilicina (=Phomopsis ilicina v. d. Aa, ined.), were the most frequent endophytes of leaves and were either absent or rare in the twig units. Two distinct kinds of sterile mycelia were common in twigs. Swiss and Spanish trees possessed fungal assemblages distinct from those present in Britain. Naturalized stands were distinguished from native stands by the presence of rather cosmopolitan and non-specific fungal taxa, rare or absent in the samples collected in the native stands. Samples derived from the native stands were colonized by more host-specific fungi. The relative frequency of two sterile mycelia in the Swiss and Spanish sites determined their separation. Phyllosticta (Phomopsis) ilicina, the most numerous leaf colonizer, was virtually absent from the bark and the xylem. The frequent occurrence of coelomycetes as endophytes of woody trees is briefly discussed.

Calmodulin interacts with amphiphilic peptides composed of all D-amino acids

Calmodulin binds to amphiphilic, helical peptides of a variety of amino-acid sequences. These peptides are usually positively charged, although there is spectroscopic evidence that at least one neutral peptide binds. The complex between calmodulin and one of its natural target peptides, the binding site for calmodulin on smooth muscle myosin light-chain kinase (RS20), has been investigated by crystallography and NMR which have characterized the interactions between the ligand and the protein. From these data, it appears that the calmodulin-binding surface is sterically malleable and van der Waals forces probably dominate the binding. To explore further this apparently permissive binding, we investigated the chiral selectivity of calmodulin using synthesized analogues of melittin and RS20 that consisted of only D-amino acids. Fluorescence and NMR measurements show that D-melittin and D-RS20 both bind avidly to calmodulin, probably in the same general binding site as that for peptides having all L-amino acids. The calmodulin-peptide binding surface is therefore remarkably tolerant sterically. Our results suggest a potentially useful approach to the design of non-hydrolysable or slowly hydrolysable intracellular inhibitors of calmodulin.

The distribution of some fungal and bacterial endophytes in maize (Zea mays L.)

Endophytic bacteria and fungi were isolated from healthy maize plants collected in a field in Devon. The average bacterial counts in the stem core tissues showed that the plant parts closer to the soil were more heavily colonized by bacteria than those near the top of the plants, and that the lower and middle part of the stems hosted the most frequently isolated bacterial species. Of the fungal species isolated, 12 had a relative importance of more than 10% in the core, 15 in the epidermis, and only 5 in the leaves. In general the distribution patterns were different among the three tissue types studied, with core and epidermis of the stems showing almost equal colonization frequencies and the leaves being most heavily colonized. More fungal species were recovered from the core and epidermis of the stem than from the leaves. The fungi most frequently isolated showed some patterns of tissue specificity, with Alternaria alternata almost exclusively associated with the leaves and Aureobasidium pullulans var. melanigerum most often present in the epidermal tissues. Assays showed low fungal colonization of seeds taken from freshly matured cobs and of seeds dried for 8 wk before testing, in contrast to higher colonization frequencies observed for the seeds used for planting. The mean values for fungal isolations in the stem pieces mostly in contact with the soil flora or close to the ground were lower than those of the more centrally placed sections. These areas of low fungal infection yielded the highest bacterial counts. The potential role of bacterial endophytes in biological control is briefly discussed.

Hemicellulose bioconversion to polyanionic heteropolysaccharides

Anionic polysaccharides, traditionally obtained from plant or algal sources, have a variety of commercial uses. Such gums from microorganisms have received increased recent interest. We have initiated a program to investigate the bioconversion of pentosans to rheologically useful anionic extracellular polysaccharides (AEPS). A number of earlier-described species, including Cryptococcus laurentii, Klebsiella pneumoniae, Arthrobacter viscosus, and Pseudomonas ATCC 31260, appear to have potential in this regard. These organisms can individually convert either xylose, enzymatic oligomeric hemicellulose digests, dilute mineral acid hemicellulose ("TVA") hydrolysates, or a five-monosaccharide mixture simulating sulfite process liquors to AEPS. The formation parameters, compositions, mol-wt distributions, and the intrinsic viscosities of these purified AEPS are exemplified. Substitution of pentose as the major substrate for glucose can result in changes in mol-wt distribution or in the percentage of noncarbohydrate substituents in some AEPS. Pursuit of these observations may lead to interesting structure-property relationships and toward rheological applications for pentosan-derived AEPS.

[Minimum data sets in ambulatory care]

A sensible and rational approach is necessary in order to match the growing requirements of information on the ambulatory care sector characterised by a big deal of complexity and variability. This must be applied to any initiative attempting to obtain any degree of harmonization in ambulatory care data sets. This paper summarises a conceptual aspect of the work undertaken by the project Measurement Characterization and Control of Ambulatory Care in Europe (McACE) sponsored by the Commission of the European Communities under the exploratory phase of the Advanced Informatics in Medicine (AIM) programme. Our approach places in the first priority the efficiency when assessing the information needs of the different actors trying to make a balanced approach between the costs of collecting and processing a specific item and its use. For this we performed a conceptual validation of the term Minimum Basic Data Set and its potential application to the Ambulatory Care Sector. It is suggested its substitution by the term Minimum Data Set as a part of a practical tool for promoting the harmonization of the information in ambulatory care.