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Biomedical subjects

D L McNeil

Publications and source records attributed to D L McNeil.

17 recordsLinked to original sources
PubMed2004

The use of a principal axis model to examine individual plant harvest index in four grain legumes.

BACKGROUND AND AIMS: A principal axis model (PAM) has been proposed to enable the selection of crop ideotypes. The PAM enables plant-to-plant variability within crops to be quantified and compared. The aim of this paper is to validate the PAM for four grain legumes. METHODS: Four grain legumes (Cicer arietinum, Lens culinaris, Lupinus angustifolius, Pisum sativum) were used to quantify the influence of plant-to-plant variability on crop yields. To create variability, populations of 10, 100 and 400 plants m(-2) were established 'on-the-square' with sowing depths of 2, 5 and 10 cm. Further, a central plant was treated with nitrogen and the impact of this on its four neighbouring plants was examined. Seeds were sown and plants harvested individually by hand. KEY RESULTS: Mean individual plant seed weight (SWT) and plant weight (PWT) decreased as plant population increased but there was a consistent and strong (R2 > 0.90) linear relationship between SWT and PWT, with a negative SWT-axis intercept in all species. These components form the basis of the principal axis model (PAM). The PAM was used to summarize the performance of individual plants within a crop and quantify the variability caused by N treatment and the lowest and highest yielding individual plants. A negative SWT-axis intercept indicated that a minimum plant weight (MPW) was required for seed production and therefore the relationship between plant harvest index (PHI) and PWT was asymptotic. The heaviest MPW was calculated for plants grown at the lowest plant population and it was species-dependent, being higher in the larger seeded species. CONCLUSIONS: Agronomic or physiological characteristics that lead to variability in PWT within a population will decrease PHI, and crop yield. The PAM may be useful in breeding programmes to identify plant phenotypes that minimize this plant-to-plant variability.

Cicer↗
PubMed2003

Comparison of isothiocyanate yield from wasabi rhizome tissues grown in soil or water.

The isothiocyanate (ITC) yield of wasabi, the Japanese horseradish (Wasabi japonica), was measured on its release from glucosinolates in the rhizomes of plants grown in two traditional ways. Mature plants of 18 months old were harvested from two different commercial farms located in the South Island of New Zealand. At one farm, the plants were grown in raised soil beds, while the plants at the other farm were grown in gravel irrigated by river water. Following harvest, the rhizomes from each growth medium were divided into five size groups based on the weight and length of the rhizomes. The different sized rhizomes were also subdivided into proximal, medial, and distal portions of the rhizomes and each portion was further subdivided into epidermis plus cortex, and vascular plus pith. The individual and total ITC contents of each portion (proximal, medial, and distal) of the rhizomes were measured using dichloromethane extraction followed by the GC-FPD. The total ITC content of the rhizomes grown in soil increased (13 times) linearly from 6 to 114 g of rhizome weight, while the mean ITC content of the water-grown wasabi increased (10 times) nonlinearly for similar sized rhizomes. Water-grown rhizomes in the weight range from 18 to 45 g gave significantly (P = 0.030) higher total ITC (1-2 times) than similarly sized soil-grown rhizomes. Analysis of the tissues showed that the total and the individual ITCs were found in significantly higher levels (73 and 64%, respectively) in the skin and cortex tissue compared to the vascular and pith tissues. Analysis of the ITC content of the different locations of the wasabi rhizome showed that the distal portion of the rhizome contained significantly higher levels of both total and individual ITCs compared to the medial and proximal portions of the rhizome.

Isothiocyanates↗
PubMed1999

Fatty acid content of New Zealand-grown walnuts (Juglans regia L.).

Walnut (Juglans regia L.) samples were collected during the 1994 and 1995 harvest from ten different cultivars of trees grown in a replicated trial in an experimental orchard at Lincoln University, New Zealand. Two US commercial cultivars (Tehama and Vina), three European commercial cultivars (Esterhazy, 139, G120) and five New Zealand selections (Rex, Dublin's Glory, Meyric, McKinster, Stanley) were evaluated. Total oil was extracted using a cold press and individual fatty acids were analysed by GLC. The total oil content of the nuts ranged from 62.4 to 68.7%. The oleic acid content of the oils ranged from 14.3 to 26.1% of the total fatty acids, while the linoleic acid content ranged from 49.3 to 62.3% and the linolenic contents from 8.0 to 13.8%.

Chromatography, Gas↗
PubMed1998

Chemical composition of hazelnuts (Corylus avellana L.) grown in New Zealand.

Hazelnut (Corylus avellana L.) samples were collected from all replications of six different cultivars of trees grown in an experimental orchard at Lincoln University. Five cultivars were originally imported from overseas, three from the USA and two from Europe, and one cultivar was selected locally. Representative samples of nuts were harvested from 12-year-old trees in autumn 1995. The total oil content of the hazelnuts ranged from 54.6 to 63.2% while the crude protein ranged from 14.3 to 18.2%. Dietary fibre ranged from 9.8 to 13.2% while the starch and free glucose content together made up no more than 5% of the remaining portion of the kernel. The amino acid content of the hazelnuts was similar between each cultivar and the pattern of essential amino acids was characteristic of a high quality protein.

Amino Acids↗
PubMed1997

Common variable immunodeficiency: diagnosis by absent ABO reverse type.

Many causes for ABO discrepancy between red blood cell and serum testing have been cited in the literature. ABO discrepancy due to weak or absent reverse type is most often seen at the extremes of age. We report a case of ABO discrepancy in a 25-year-old woman who presented for wisdom teeth extraction. Initial serologic workup revealed total absence of isohemagglutinin anti-B in this group A, D+ individual. Further evaluation revealed decreased levels of all classes of immunoglobulins and a medical history significant for multiple episodes of infection. Based on the patient's history and laboratory data, she was diagnosed with common variable immunodeficiency (CVID). CVID can cause ABO discrepancy in an adult patient because of an absent ABO reverse type.

Journal Article↗
PubMed1990

Oral gold therapy in steroid-dependent asthma, nasal polyposis, and aspirin hypersensitivity.

Eight patients are described who fulfill the criteria for the triad of asthma, nasal polyposis, and aspirin hypersensitivity who have been treated with oral chrysotherapy from 7 to 17 months. Patient diary and symptom scores reflect an overall improvement in global symptoms. Monthly pulmonary assessment (spirometry) does not indicate a significant change (improvement or deterioration) but average daily oral prednisone requirements have decreased. One of eight patients experienced a minor side effect of treatment but did not require discontinuation of therapy. Oral gold therapy may prove to be an alternative therapy in a select population of patients and permit a reduction or discontinuation of oral corticosteroid therapy.

Adrenal Cortex Hormones↗
PubMed1986

Hospital closure: who will be at risk in the upcoming decade?

Although the number of community hospitals that close in the United States is not large in proportion to the number that remain open, hospital closure is attracting increasing attention. National trends and patterns of closure occurring over the last five years, 1980-1984, can be seen in terms of hospital bed size, control, location, period of operation, and financial characteristics. These trends indicate that those hospitals that close generally are small, urban, and investor-owned or nongovernment, not-for-profit; they have been in existence for quite some time; and have low current ratios, net to gross patient revenue ratios, and total margins.

Catchment Area, Health↗
PubMed1985

Isolation and properties of soybean [Glycine max (L.) Merr.] mutants that nodulate in the presence of high nitrate concentrations.

Soybean seeds [Glycine max (L.) Merr. ev. Bragg] were mutagenized with ethyl methanesulfonate. The M(2) progeny (i.e., the first generation after mutagenesis) of these seeds were screened for increased nodulation under high nitrate culture conditions. Fifteen independent nitrate-tolerant symbiotic (nts) mutants were obtained from 2500 M(2) families. In culture on sand with KNO(3), nodule mass and nodule number in mutant lines were several-fold those of the wild type cultured under the same conditions. Inheritance of the nts character through to subsequent generations was observed in the 10 mutants tested. Mutant nts382 also nodulated more than the wild type in the absence of nitrate. Furthermore, nitrate stimulated growth in both the wild type and nts382, and these lines had similar nitrate reductase activity. These results indicate that nts382 is affected in a nodule-development regulatory gene and not in a gene related to nitrate assimilation.

Journal Article↗
PubMed1985

A Supernodulation and Nitrate-Tolerant Symbiotic (nts) Soybean Mutant.

The nodulation characteristics of soybean (Glycine max) mutant nts382 are described. The mutant nodulated significantly more than the parent cultivar Bragg in the presence and absence of several combined nitrogen sources (KNO(3), urea, NH(4)Cl, and NH(4)NO(3)). The number of nodules on the tap root and on lateral roots was increased in the mutant line. In the presence of KNO(3) and urea, nitrogenase activity was considerably higher in nts382 than in Bragg. Mutant plants were generally smaller than wild-type plants. Although nts382 is a supernodulator, inoculation with Rhizobium japonicum was necessary to induce nodule formation and both trial strains CB1809 (= USDA136) and USDA110 elicited the mutant phenotype. Segregation of M(3) progeny derived from a M(2) wild-type plant indicated that the mutant character is inherited as a Mendelian recessive. The mutant is discussed in the context of regulation of nodulation and of hypotheses that have been proposed to explain nitrate inhibition of nodulation.

Journal Article↗
PubMed1984

Effect of nitrogen source on ureides in soybean.

In field-grown soybeans (Glycine max L. Merr. cv Harosoy), the percentage of N in the xylem as ureides increased with increasing N(2) fixation. During a 9-week collection period, the ureide content varied from 9.0 to 69.2% of the xylary N. Between 9 and 11 weeks (early pod fill), there was a good correlation (r = 0.93) between C(2)H(2) reduction and the per cent N in xylem as ureides. The per cent N as ureides, however, does not always indicate the reliance of the plant on symbiotic N(2) fixation. This ureide content also depended on the level of NO(3) (-) available to the roots. Non-nodulated soybeans given from 0 to 200 kilogram N per hectare produced xylem sap which averaged from 31.8% to 9.0% N, respectively, in the xylem as ureides over the 9-week period.Feeding of (15)N(2), (15)NH(4), or (15)NO(3) to greenhouse-grown soybeans indicated substantial differences in the initial distribution of N by the xylem stream, but the ultimate distribution of N between plant parts and grain did not vary with available N or percentage of xylary N as ureides. Amino acids, not ureides, were the major source of N in the phloem. The soybeans maintained a similar composition in phloem irrespective of the xylem sap constituents, with N derived from N(2), NH(4), or NO(3) being equally accessible to the phloem stream.

Journal Article↗
PubMed1982

Variations in Ability of Rhizobium japonicum Strains To Nodulate Soybeans and Maintain Fixation in the Presence of Nitrate.

This study investigated differences in sensitivity to nitrate of soybean (Glycine max cv. Davis) symbioses with 16 different Rhizobium japonicum strains. When nitrate (20 mM) was added to established symbioses, there were no significant differences in the degree of inhibition of acetylene reduction for any of the 16 strains. When nitrate was present during the establishment of nodules, high levels of nitrate (10 mM) were equally inhibitory on all symbioses, whereas specific strain effects appeared at low (0.5 mM) to medium (2.0 mM) levels of nitrate. At 1.5 mM nitrate in solution culture, the days to emergence of nodules varied from less than 10 (CB:1809, Nit61A118) to more than 16 (11 of 16 strains). In a clay-pot trial maintained at the low nitrate level (0.5 mM), symbioses with CB:1809 increased total nodule mass by 30% relative to nitrate-free controls. In the presence of 2.0 mM nitrate, CB:1809 maintained total nodule mass. For the remaining 6 strains tested, total nodule mass decreased to below the levels of the nitrate-free controls. In a separate clay pot trial, CB:1809 increased its competitive ability relative to USDA:110 when nitrate was added. If no nitrate was added, CB:1809 occupied 0.97 times as many nodules as USDA:110; when 10 mM nitrate was added, CB:1809 occupied 1.75 times as many nodules as USDA:110. Attempts to select nitrogen-adapted substrains of R. japonicum through sequential isolation and infection of plants grown on nitrate were not successful.

Journal Article↗
PubMed1979

Modeling the transport and utilization of carbon and nitrogen in a nodulated legume.

An empirical modeling technique was developed for depicting quantitatively the transport and partitioning of photosynthetically fixed C and symbiotically fixed N during 10-day intervals of a 40-day period in the growth of nodulated plants of white lupin (Lupinus albus L. cv. Ultra). Model construction utilized data for C and N consumption of plant parts and C:N weight ratios of the xylem and phloem fluids serving specific plant organs. Formulas were derived from calculating the net transport of C and N between plant parts in xylem and phloem. The models provided quantitative information on the dependence of growing organs on xylem and phloem for their supply of C and N, the cycling of N through leaflets and of C through nodules, the extent of direct incorporation of fixed N into growing nodules, and the involvement of N from shoot translocate in the nutrition of the nodulated root. Stem plus petioles abstracted considerably more N from xylem than expected from their transpirational activity. Xylem to phloem transfer of recently fixed N in mature stem and petioles was substantiated by the models, being depicted as a device for dispensing N to growing parts of the shoot extra to that attracted transpirationally in xylem or received as translocate from leaflets.

Journal Article↗
PubMed1979

Uptake and Utilization of Xylem-borne Amino Compounds by Shoot Organs of a Legume.

Amino compounds representative of the major N solutes of xylem sap were pulse-fed (10 to 20 minutes) singly in (14)C-labeled form to cut transpiring shoots of white lupin (Lupinus albus L.). (14)C distribution was studied by autoradiography and radioassays of phloem sap, leaflet tissues, and shoot parts harvested at intervals after labeling. Primary distribution of N by xylem was simulated using a 20-minute labeling pulse followed by a 30-minute chase in unlabeled xylem sap. Shoots fed (14)C-labeled asparagine, glutamine, valine, serine, or arginine showed intense labeling of leaflet veins and marked retention (35 to 78%) of (14)C by stem + petioles. Shoots fed (14)C-labeled aspartic acid or glutamic acid showed heaviest (14)C accumulation in interveinal regions of leaflets and low uptake (11 to 20%) of (14)C by stem + petioles. Departing leaf traces were major sites of uptake of all amino compounds, and the implications of this were evaluated. Fruits acquired only 1 to 5% of the fed label directly from xylem, but more than doubled their intake during the period 30 to 160 minutes after feeding through receipt of (14)C transferred from xylem to phloem in stem and leaves. (14)C-Labeled asparagine and valine transferred directly from xylem to phloem, but the (14)C of (14)C-labeled aspartic acid and arginine appeared in phloem mainly as metabolic products of the fed compound. The labeling of the soluble pool of leaflets reflected these differences. The significance of heterogeneity in distribution and metabolism of xylem amino compounds in the shoot was discussed.

Journal Article↗
PubMed1979

Transport of organic solutes in Phloem and xylem of a nodulated legume.

Collections of xylem exudate of root stumps or detached nodules, and of phloem bleeding sap from stems, petioles, and fruits were made from variously aged plants of Lupinus albus L. relying on nodules for their N supply. Sucrose was the major organic solute of phloem, asparagine, glutamine, serine, aspartic acid, valine, lysine, isoleucine, and leucine, the principal N solutes of both xylem and phloem. Xylem sap exhibited higher relative proportions of asparagine, glutamine and aspartic acid than phloem sap, but lower proportions of other amino acids. Phloem sap of petioles was less concentrated in asparagine and glutamine but richer in sucrose than was phloem sap of stem and fruit, suggesting that sucrose was unloaded from phloem and amides added to phloem as translocate passed through stems to sinks of the plant. Evidence was obtained of loading of histidine, lysine, threonine, serine, leucine and valine onto phloem of stems but the amounts involved were small compared with amides. Analyses of petiole phloem sap from different age groups of leaves indicated ontogenetic changes and effects of position on a shoot on relative rates of export of sucrose and N solutes. Diurnal fluctuations were demonstrated in relative rates of loading of sucrose and N solutes onto phloem of leaves. Daily variations in the ability of stem tissue to load N onto phloem streams were of lesser amplitude than, or out of phase with fluctuations in translocation of N from leaves. Data were related to recent information on C and N transport in the species.

Journal Article↗