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PubMed2006

Consequences for host-parasitoid interactions of grazing-dependent habitat heterogeneity.

1. Environmental heterogeneity can produce effects that cascade up to higher trophic levels and affect species interactions. We hypothesized that grazing-dependent habitat heterogeneity and grazing-independent host plant heterogeneity would influence directly and indirectly a host-parasitoid interaction in a woodland habitat. 2. Thistles were planted randomly in 20 birch woodlands, half of which are grazed by cattle. The abundances of two species of seed herbivore and their shared parasitoid were measured, and related to habitat and host-plant heterogeneity. 3. The presence of cattle grazing created a structurally and compositionally distinct plant assemblage from the ungrazed seminatural situation. Grazing did not affect the number or dispersion of the host plant underpinning the host-parasitoid interaction. 4. The density of one insect herbivore, Tephritis conura, and its parasitoid Pteromalus elevatus was significantly increased by the presence of cattle; but another herbivore, Xyphosia miliaria, was unaffected. The percentage of parasitism of T. conura was increased in grazed habitat occurring at twice the rate found in ungrazed habitat. 5. The increase in T. conura abundance was correlated with increased species richness and cover of forbs in grazed sites. This effect of grazing-dependent habitat variation on host insect density cascaded up to parasitoid density and percentage of parasitism. Habitat heterogeneity had a further direct, positive effect on parasitoid density and percentage of parasitism after controlling for host-insect density. 6. Independent of grazing, heterogeneity in host-plant flowering, architecture and stature further affected T. conura and its parasitoid's densities. Parasitoid density was also affected by the dispersion of the host plant. 7. A combination of habitat and host-plant scale environmental heterogeneity influenced a host-parasitoid interaction indirectly and directly, providing a rare example of an anthropogenic disturbance positively affecting a tertiary trophic level. This finding highlights the need to consider not only the importance of bottom-up effects for top-down processes, but also the role of environmental heterogeneity arising from anthropogenic disturbance for trophic interactions such as parasitism.

Animals↗
PubMed2004

Influences of vermicomposts on field strawberries: 1. effects on growth and yields.

Vermicomposts processed commercially from food wastes and paper wastes were applied, to 4.5 m(2) field plots, under high plastic hoop tunnels, at rates of 5 or 10 tha(-1) to evaluate their effects on the growth and yields of strawberries (Fragaria ananasa) var. 'Chandler'. The vermicomposts were incorporated into the top 10 cm of soil and supplemented, based on chemical analyses, with amounts of inorganic NPK fertilizers calculated to equalize the initial fertilizer rates of 85-155-125 kgha(-1) NPK applied to the inorganic fertilizer plots. All treatments were replicated four times, in a completely randomized design, at two field sites on Doles silt loam or Hoytville silty clay loam at Piketon and Fremont, Ohio, respectively. Vermicompost applications increased strawberry growth and yields significantly; including increases of up to 37% in leaf areas, 37% in plant shoot biomass, 40% in numbers of flowers, 36% in numbers of plant runners and 35% in marketable fruit weights. These responses seemed not to be dose-dependent, since strawberries at one site grew fastest and yielded most in response to the 10 tha(-1) vermicompost application rate, whereas they responded positively and similarly to both the 5 and 10 tha(-1) rates of applications at the other site. These responses could not have been mediated by availability of macronutrients, since all plots were supplemented with inorganic fertilizers, to equalize macronutrient inputs for all treatments, but based on other research in our laboratory could have been due to production of plant growth regulators by microorganisms during vermicomposting.

Agriculture↗
PubMed1991

Effects of elevated CO2 concentration on the polyamine levels of field-grown soybean at three O3 regimes.

Effects of increased ozone (O3) and carbon dioxide (CO2) on polyamine levels were determined in soybean (Glycine max L. Merr. cv. Clark) grown in open-top field chambers. The chamber treatments consisted of three O3 regimes equal to charcoal filtered (CF), non-filtered (NF), and non-filtered plus 40 nl litre(-1) O3 and CO2 treatments equal to 350, 400 and 500 microl litre(-1) for a total of nine treatments. Leaf samples were taken at three different times during the growing season. Examination of growth and physiological characteristics, such as photosynthesis, stomatal resistance, and shoot weight, revealed that increasing CO2 ameliorated the deleterious effects of increased O3. Results from the initial harvest, at the pre-flowering growth stage (23 days of treatment), showed that increasing O3 at ambient CO2 caused increases in putrescine (Put) and spermidine (Spd) of up to six-fold. These effects were lessened with increased CO2. Elevated CO2 increased polyamines in plants treated with CF air, but had no effect in the presence of ambient or enhanced O3 levels. Leaves harvested during peak flowering (37 days of treatment) showed O3-induced increases in Put and Spd at ambient CO2 concentrations. However, increased CO2 levels inhibited this response by blocking the O3-induced polyamine increase. Leaves harvested during the pod fill stage (57 days of treatment) showed no significant O3 or CO2 effects on polyamine levels. Our results demonstrate that current ambient O3 levels induce the accumulation of Put and Spd early in the growing season and that further increases in O3 could result in even greater polyamine increases. These results are consistent with a possible antiozonant function for polyamines. The ability of increased CO2 to protect soybeans from O3 damage, however, does not appear to involve polyamine accumulation.

Journal Article↗
PubMed2024

Organ-delimited gene regulatory networks provide high accuracy in candidate transcription factor selection across diverse processes.

Organ-specific gene expression datasets that include hundreds to thousands of experiments allow the reconstruction of organ-level gene regulatory networks (GRNs). However, creating such datasets is greatly hampered by the requirements of extensive and tedious manual curation. Here, we trained a supervised classification model that can accurately classify the organ-of-origin for a plant transcriptome. This K-Nearest Neighbor-based multiclass classifier was used to create organ-specific gene expression datasets for the leaf, root, shoot, flower, and seed in Arabidopsis thaliana. A GRN inference approach was used to determine the: i. influential transcription factors (TFs) in each organ and, ii. most influential TFs for specific biological processes in that organ. These genome-wide, organ-delimited GRNs (OD-GRNs), recalled many known regulators of organ development and processes operating in those organs. Importantly, many previously unknown TF regulators were uncovered as potential regulators of these processes. As a proof-of-concept, we focused on experimentally validating the predicted TF regulators of lipid biosynthesis in seeds, an important food and biofuel trait. Of the top 20 predicted TFs, eight are known regulators of seed oil content, e.g., WRI1, LEC1, FUS3. Importantly, we validated our prediction of MybS2, TGA4, SPL12, AGL18, and DiV2 as regulators of seed lipid biosynthesis. We elucidated the molecular mechanism of MybS2 and show that it induces purple acid phosphatase family genes and lipid synthesis genes to enhance seed lipid content. This general approach has the potential to be extended to any species with sufficiently large gene expression datasets to find unique regulators of any trait-of-interest.

Arabidopsis↗
PubMed2006

Internode structure and cell wall composition in maturing tillers of switchgrass (Panicum virgatum. L).

This work examined cell composition gradients in maturing tillers of switchgrass (Panicum virgatum L.) with the aim of developing baseline information on this important forage and biomass crop. Flowering tillers were collected from plants raised from seeds in a greenhouse and field, harvested at soil level and separated into internodes beginning with the node subtending the peduncle. Internodes were analyzed using microscopy, by fiber digestion, high-performance liquid chromatography and by gas chromatography-mass spectrometry to obtain anatomical and compositional data. Microscopy demonstrated the development and maturation of cortical fibers which eventually became confluent with the fiber sheath surrounding vascular bundles in the lower internodes. Detergent fiber analysis indicated increasing cellulose and lignin contents and decreases in cell solubles and hemicelluloses with increasing distance of the internodes from the top of the plant. Soluble phenolics were greatest in amounts and complexity in top internodes. The lower internodes contained greater levels of wall-bound phenolic acids, principally as 4-coumarate and ferulate.

Biomass↗
PubMed1993

Anti-inflammatory actions of an N-terminal peptide from human lipocortin 1.

An acetylated polypeptide corresponding to residues 2-26 of human lipocortin 1 was synthesized and the anti-inflammatory activity assessed in three models of acute inflammation in rat and mouse. In the carrageenin rat paw oedema test, the peptide produced a maximal inhibition of approximately 41% at the 3 h time point with a 10 micrograms dose. When rat paw oedema was induced by the injection of venom phospholipase A2, the peptide produced a significant inhibition (31%) at the top dose of 20 micrograms per paw. In the mouse air-pouch model, systemic treatment with the peptide produced a dramatic reduction in cytokine-induced leukocyte migration with an ID50 of approximately 40 micrograms per mouse. The N-terminal peptide 2-26 shares the actions of lipocortin 1 in these acute models of inflammation.

Amino Acid Sequence↗
PubMed1997

ETTIN patterns the Arabidopsis floral meristem and reproductive organs.

ettin (ett) mutations have pleiotropic effects on Arabidopsis flower development, causing increases in perianth organ number, decreases in stamen number and anther formation, and apical-basal patterning defects in the gynoecium. The ETTIN gene was cloned and encodes a protein with homology to DNA binding proteins which bind to auxin response elements. ETT transcript is expressed throughout stage 1 floral meristems and subsequently resolves to a complex pattern within petal, stamen and carpel primordia. The data suggest that ETT functions to impart regional identity in floral meristems that affects perianth organ number spacing, stamen formation, and regional differentiation in stamens and the gynoecium. During stage 5, ETT expression appears in a ring at the top of the floral meristem before morphological appearance of the gynoecium, consistent with the proposal that ETT is involved in prepatterning apical and basal boundaries in the gynoecium primordium. Double mutant analyses and expression studies show that although ETT transcriptional activation occurs independently of the meristem and organ identity genes LEAFY, APETELA1, APETELA2 and AGAMOUS, the functioning of these genes is necessary for ETT activity. Double mutant analyses also demonstrate that ETT functions independently of the 'b' class genes APETELA3 and PISTILLATA. Lastly, double mutant analyses suggest that ETT control of floral organ number acts independently of CLAVATA loci and redundantly with PERIANTHIA.

Amino Acid Sequence↗
PubMed2006

Seasonal variation of diet and food availability in a group of Sichuan snub-nosed monkeys in Shennongjia Nature Reserve, China.

We studied the diet and food availability of a group of Sichuan snub-nosed monkeys for 14 months (July 2003 to September 2004, except for February) in the Shennongjia Nature Reserve, China. This species is primarily a lichen eater, with lichens (Usneaceae) accounting for 43.28% of feeding records (n=3,452). Other food types in the diet were young leaves (28.71%), fruits or seeds (14.57%), buds (5.36%), mature leaves (3.51%), herbs (2.09%), bark (1.36%), and flowers (1.13%). The monkeys used 23 plant species. Their diet showed a complicated seasonal variation: the monthly diet varied from primarily lichens in November-April, to a mixture of leaves and lichens in May-July, to a mixture of fruits or seeds and lichens in August-October (the latter depended on annual fruit and seed availability). The proportion of fruits or seeds in the diet was negatively correlated with that of lichens, which suggests that the monkeys prefer fruits or seeds to lichens when all of these items are available. The fruit or seed availability varied greatly between the two study years. The proportion of lichens, young leaves, flowers, and fruits or seeds in the diet was positively associated with their availability. The monkeys appeared to be selective feeders. They preferred 10 tree species for plant parts, and nine tree species for lichens. The selection index of tree species for lichens was positively related to lichen coverage per branch on tree species, demonstrating that the monkeys preferred tree species with abundant lichens, as well as dead trees for lichens. The results suggest that dead-tree harvesting in the reserve could significantly reduce the quality of habitat for these monkeys, and should therefore be prohibited. Connus controversa, Cerasus discadenia, Salix willichiana, and Malus halliana should be conserved as top priority species because the monkeys preferred them for both their vegetative parts and the lichens that grow on them.

Animal Nutritional Physiological Phenomena↗
PubMed2006

Plumbism or lead intoxication mimicking an abdominal tumor.

The clinical presentation of lead intoxication may vary widely and in the absence of a high clinical index of suspicion, the diagnosis may be missed. The effects of lead on mitochondrial oxidative phosphorylation and its interaction with calcium-mediated processes explain the heterogenous presentation. In this case report, the diagnosis was finally made when bilateral wrist drop developed on top of abdominal cramps and anemia. Before, ascites raised the suspicion of a tumor. Therefore, each element of the triad of unexplained anemia, abdominal cramps, and bilateral wrist (or foot) drop should lead any physician to consider the diagnosis of lead intoxication. This case also illustrates the importance of a careful and meticulous social history in patient management.

Abdominal Neoplasms↗
PubMed2005

Solid waste management techniques for the waste generated and brought down from campsites in the hill spots, trails and expedition tops.

The increasing self-generated solid waste from the visitors in the hill towns, trails and expedition tops is one of the most adverse forms of human impacts in mountain environments. The direct managing authorities, such as municipalities in the hill spots, have no proper places to dispose of municipal waste nor the other infrastructure required nor adequate funds. The trekking and expedition areas are entirely dependent on the moral responsibilities of the local people, as well as visitors, because these locations are in remote areas, outside municipal boundaries. Based on five major case studies representing the Himalayas, the status of solid waste generation, its physical composition and management options in tourist [Kullu: 1,219 metres above average sea level (m), Rewalsar: 1,300 m, Manali: 2,050 m], trekking (in and around the Valley of Flowers: 1,830-4,330 m) and expedition areas (Pindari valley: 2,300-5,500 m) were studied. The inflow of visitors ranged from 150,000 to 1,140,251 in the hill spots, and from 25,000 to 116,392 in the expedition and trekking areas, respectively. The capita = t day 1 waste generation varied from 200-300 g in hill spots and from 200-288 g in expedition and trekking areas, respectively. Biodegradable waste varied from 65.2 to 83.1% of the total waste generated and was of greater quantity than non-biodegradable waste in expedition areas. Non-biodegradable waste was the predominant form in the expedition (66.4%) and trekking areas (84.5%). The ultimate aim of the study is to make the concerned local people, visitors and government aware of the need to harness energy from waste. This can be done in various ways including biocomposting, and the reuse and recycling of waste otherwise considered valueless and useless.

Altitude↗
PubMed1977

Metabolism and distribution of cyclohexanecarboxylic Acid, a plant growth stimulant, in bush bean.

A foliar spray of 10 mm cyclohexanecarboxylic acid (CHC), a component of the growth stimulant naphthenic acid, to primary leaves of 14-day-old plants of bush bean, Phaseolus vulgaris L., cv Top Crop, resulted in increased vegetative growth and pod production. One minute after the application of 0.5 mm CHC-7-(14)C (CHC(*)) to a primary leaf, CHC(*) was present within it. The chief conversion of the CHC(*) in the leaf during the interval 15 minutes to 4 hours after the acid had been applied appeared to be CHC(*) to its glucose conjugate (CHC(*)-G), and during 4 to 48 hours, CHC(*)-G to CHC(*)-aspartate and an unknown metabolite. Radioactivity was confined to the leaf for at least 1 hour, but by the 12th hour was detected throughout the plant. In the interval 1 to 4 weeks after CHC(*) application, the mean percentage distribution of radioactivity was: treated leaf, 65.3; roots, 18.8; stem, 7.7; trifoliate leaves, 5.9; flower buds-flowers-pods, 2.3. During this period CHC(*)-G was the most prominent metabolite in all organs; no free CHC(*) was detected. Light favored the movement of CHC(*) conjugates out of the leaf; glucose fed to dark-grown plants substituted for light to some extent but aspartate was relatively ineffective, suggesting the dependence of outward movement on ATP. The presence of the glucose and aspartate conjugates of the acid in all organs of CHC-treated plants and the absence of free CHC from them suggest that one or both conjugates, rather than the acid itself, are involved in growth stimulation.

Journal Article↗
PubMed1999

Structure of acetylcholinesterase complexed with (-)-galanthamine at 2.3 A resolution.

(-)-Galanthamine (GAL), an alkaloid from the flower, the common snowdrop (Galanthus nivalis), shows anticholinesterase activity. This property has made GAL the target of research as to its effectiveness in the treatment of Alzheimer's disease. We have solved the X-ray crystal structure of GAL bound in the active site of Torpedo californica acetylcholinesterase (TcAChE) to 2.3 A resolution. The inhibitor binds at the base of the active site gorge of TcAChE, interacting with both the choline-binding site (Trp-84) and the acyl-binding pocket (Phe-288, Phe-290). The tertiary amine group of GAL does not interact closely with Trp-84; rather, the double bond of its cyclohexene ring stacks against the indole ring. The tertiary amine appears to make a non-conventional hydrogen bond, via its N-methyl group, to Asp-72, near the top of the gorge. The hydroxyl group of the inhibitor makes a strong hydrogen bond (2.7 A) with Glu-199. The relatively tight binding of GAL to TcAChE appears to arise from a number of moderate to weak interactions with the protein, coupled to a low entropy cost for binding due to the rigid nature of the inhibitor.

Acetylcholinesterase↗
PubMed2000

Functional and positional difference and classification of the fungiform papillae on the rabbit tongue seen in microvascular cast specimens by means of scanning electron microscope.

The relationships between the functional and morphological characteristics, the positional difference and classification seen in microvascular cast specimens (MVCS) of the fungiform papillae (FuP) on the anterodorsal surface and both sides of the intermolar eminence (IME) of the rabbit tongue were examined and compared by means of scanning electron microscopy (SEM). The small fungiform papillae (S-FuP), scattered sporadically among the numerous small filiform papillae (SfP), were found to be distributed irregularly over the anterodorsal surface. The large fungiform papillae (L-FuP), distributed in a length-wise line in the anterior to the posterior direction among the SfP, were found to be distributed on both peripheral sides of the IME. FuPs consisted of the ascending and descending capillary loops, forming the central hole on the top of the FuP, resembling a carnation, the petals of which numbered eight to twelve, and were wider and more complex in shape and size than SfPs were morphologically different. S-FuPs can be classified into three types: type I (consisting of eight petals), type II (ten petals) and type III (twelve petals) according to the shape of the FuP and the number of petals, L-FuPs, were larger and wider than S-FuPs and of a more complex shape, classified into two types: type I (consisting of ten petals) and type II (twelve petals) according to the shape of the FuP and the number of petals in the MVCS of FuPs as seen in SEM. These results suggest that the petals in the ascending and descending capillary loops of the FuP expand into flower-like figures, increase on the surface and play an effective role in receiving the taste sense from foods and liquids on the antero-dorsal surface and both peripheral sides of the IME.

Animals↗
PubMed2000

Growth responses to ozone in plant species from wetlands.

Ten wet grassland species were fumigated with four concentrations of ozone (charcoal-filtered air, non-filtered air and non-filtered air plus 25 or 50 nl l(-1) ozone) in open-top chambers during one growing season to investigate the long-term effect of this air pollutant on various growth variables. Only Eupatorium cannabinum showed ozone-related foliar injury, while five species reacted with significantly ozone-enhanced senescence. Premature senescence was paralleled by a significant ozone-induced reduction of green leaf area in Achillea ptarmica, E. cannabinum and Plantago lanceolata. At the intermediate harvest performed after 28 days shoot weights were significantly decreased by ozone in A. ptarmica and increased in Molinia caerulea. At the final harvest performed at the end of the growing season two other species, Cirsium dissectum and E. cannabinum had a significantly reduced shoot weight due to ozone. Root biomass was determined only at the intermediate harvest. The root:shoot ratio (RSR) was significantly reduced in C. dissectum, while it increased in M. caerulea. Seven of the species developed flowers during the experiment. While no significant ozone effects on flowering date and flower numbers were detected, flower weights were significantly reduced in E. cannabinum and P. lanceolata.

Journal Article↗
PubMed2005

Enemy release but no evolutionary loss of defence in a plant invasion: an inter-continental reciprocal transplant experiment.

When invading new regions exotic species may escape from some of their natural enemies. Reduced top-down control ("enemy release") following this escape is often invoked to explain demographic expansion of invasive species and also may alter the selective regime for invasive species: reduced damage can allow resources previously allocated to defence to be reallocated to other functions like growth and reproduction. This reallocation may provide invaders with an "evolution of increased competitive ability" over natives that defend themselves against specialist enemies. We tested for enemy release and the evolution of increased competitive ability in the North American native ragweed (Ambrosia artemisiifolia: Asteraceae), which currently is invading France. We found evidence of enemy release in natural field populations from the invaded and native ranges. Further we carried out a reciprocal transplant experiment, comparing several life history traits of plants from two North American (Ontario and South Carolina) and one French population in four common gardens on both continents. French and Canadian plants had similar flowering phenologies, flowering earlier than plants from further south in the native range. This may suggest that invasive French plants originated from similar latitudes to the Canadian population sampled. As with natural populations, experimental plants suffered far less herbivore damage in France than in Ontario. This difference in herbivory translated into increased growth but not into increased size or vigour. Moreover, we found that native genotypes were as damaged as invading ones in all experimental sites, suggesting no evolutionary loss of defence against herbivores.

Ambrosia↗
PubMed1990

New York's statewide approach to increase the number of minority applicants to medical school.

The Associated Medical Schools of New York (AMS), a consortium of 13 public and private medical schools, has identified the problem of low minority enrollment as its top priority issue. Over the last six years, the consortium has established a multifaceted, statewide effort aimed at increasing the pool of qualified minority applicants. The programs include academic enrichment for precollege and college students, recruitment conferences, and a program to attract minority applicants to residency training in New York. The key to this effort is the work of the AMS Office of Minority Affairs, which provides statewide oversight and coordinates these programs. The consortium approach has proven attractive to both private philanthropy and government funding sources and provides a mechanism for evaluation. The most valid evaluation will occur in about three years, when graduates of the precollege program begin to apply to medical school.

Education, Medical↗
PubMed1976

Goblet cell membrane differentiations in the midgut of a lepidopteran larva.

So-called goblet cells are present in the midgut of lepidopteran larvae. They are thought to be involved in the active transport of potassium out of the haemolymph and into the gut lumen. A number of plasma membrane differentiations within the goblet cell cavity has been investigated using conventional staining, lanthanum tracer and freeze-etch techniques. Of particular interest are junction-like inter- and intra-membrane differentiations found on the villus-like cytoplasmic projections present at the apical tip of the goblet cell cavities. These cytoplasmic projections appear to act as a valve; in some cases they seem to close off the top of the goblet cell cavity, so isolating it from the gut lumen, while in other cases they are spread apart leaving a wide channel from the cavity into the lumen. The junction-like structures on these cytoplasmic projections are different in structure from the septate-type junctions which seal the midgut cells together at their apical borders, and the 2 types are present on the same plasma membrane, often within one micron of each other. The need for a different type of junction may possibly be related to the fact that it occurs between 2 areas of the same plasma membrane. The morphology of this unusual junction-like structure is discussed and 2 diagrams are presented to illustrate our interpretation of its structure.

Animals↗
PubMed2006

Three-dimensional reciprocity of floral morphs in wild flax (Linum suffruticosum): a new twist on heterostyly.

Here, we studied the floral morphology and pollination of the distylous plant Linum suffruticosum (Linaceae) in southern Spain. We observed a previously unreported form of distyly that involved twisting and bending of styles and stamens during floral development to achieve three-dimensional reciprocity of anthers and stigmas in the long-styled (pin) and short-styled (thrum) morphs. This developmental pattern causes pin pollen to be placed on the underside of pollinating Usia flies (Bombyliidae), and thrum pollen to be placed on the top of the thorax and abdomen. The pin stigmas contact the flies on the dorsum, apparently picking up predominantly thrum pollen, and the thrum stigmas contact the flies on the ventral surface, apparently picking up predominantly pin pollen. This form of heterostyly would appear on morphological grounds to be far more efficient in dispersing pollen between compatible morphs than the typical pin-thrum system. If so, this plant fits Darwin's prediction of efficient pollen flow between heterostylous morphs more closely than anything Darwin himself reported. Molecular phylogenetic analyses indicate that this form of heterostyly evolved in a lineage that already had typical heterostyly. The analyses also indicate that there have been several independent origins of heterostyly in Linum and at least one reversal to stylar monomorphism.

Animals↗