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PubMed2006

Seasonal variation of microbial ecology in hemlock soil of Tatachia Mountain, Taiwan.

BACKGROUND AND PURPOSE: Forest soil microorganisms and fauna decompose the organic materials, and thus strongly influence the nutrient cycling of the ecosystem. Soil microorganisms also contribute to soil structure and soil fertility. In Taiwan, the microbial distributions of soils have only been determined in acidic soil, inorganic acidic soil, upland soil, alkaline soil and power plant areas. There are few data on the microbial populations of forest soils. Tatachia Mountain is located in the central part of Taiwan and is a typical high altitude protected ecosystem area, designated as a National Park. This study investigated the role of microorganisms in the ecology and nutrient transformation of forest soil in Taiwan. METHODS: As part of long-term ecological research in Taiwan, the environmental conditions, seasons, microbial populations, biomass and organic acid contents of hemlock soil were investigated. We also studied the effect of depth on microbial populations and biomass. RESULTS: The soil temperatures were between 5.5 and 15.6 degrees C and the soil pH ranged from 3.3 to 4.4. Total organic carbon and total nitrogen contents ranged from 2.3 to 37.1% and from 0.3 to 1.7%, respectively. The carbon/nitrogen ratio was between 8.2 and 24.4. In topsoil, each gram of soil contained 10(5)-10(7) colony-forming units (CFU) culturable bacteria, 10(2)-10(5) CFU actinomycetes, 10(3)-10(5) CFU fungi, 10(4)-10(6) CFU cellulolytic microbes, 10(4)-10(6) CFU phosphate-solubilizing microbes, and 10(3)-10(6) CFU nitrogen-fixing microbes. Microbial populations were higher in topsoil compared with subsoil, but lower in topsoil than in organic layer. Microbial populations also decreased with the depth of soil. Microbial populations at 1E horizon were 0.6% to 9.4% of those at O horizon. The microbial biomass evaluated contained carbon 391-1013 mug, nitrogen 51-146 mug, malic acid 76-557 nM and succinic acid 37-527 nM per gram of soil. Summer season had higher microbial populations, biomass and organic content than winter season, but the differences were not significant. CONCLUSION: Heavy coverage of organic matter was found in hemlock and spruce soils and was associated with acidic pH. Microbial populations decreased with increasing soil depth. Microbes play a very important role in organic matter decomposition and nutrition transformation in hemlock soil.

Actinobacteria↗
PubMed2006

Temporal and spatial variation of terpenoids in eastern hemlock (Tsuga canadensis) in relation to feeding by Adelges tsugae.

The terpenoid content of eastern hemlock (Tsuga canadensis) foliage was measured over an annual cycle of development from bud opening, shoot elongation, shoot maturation, to bud-break at the start of the next growing season. The objective was to determine if variation in terpenoid composition is linked with spatial and temporal feeding preferences of the hemlock woolly adelgid (HWA; Adelges tsugae). The HWA has two periods of feeding over the course of 1 yr spanning two complete generations. There are two periods of feeding separated by a nonfeeding period where the adelgid estivates. HWA prefers to feed on mature, rather than young, expanding tissue. Feeding occurs in the leaf cushion at the base of the needle. The needle is the only tissue in hemlock with resin canals that store terpenoids. The needle and leaf cushion of both the current and previous years' growth were analyzed separately over a 1-yr period to examine the variation of terpenoid composition in space and time. Terpenoids were quantified by using headspace solid-phase microextraction/gas chromatography/mass spectrometry (SPME/GC/MS). New growth needles and leaf cushions do not resemble the previous year's growth either visually or in chemical composition until October/November, when the adelgid breaks estivation and begins feeding. Nearly all of the 23 terpenoids present exceeding 0.1% varied significantly either temporally or spatially, usually with complex interactions. Ordination and factor analysis revealed that terpenoids are less variable in mature leaf cushions than in young tissue. By entering a nonfeeding diapause during the late spring and summer, HWA avoids the unstable, variable levels of terpenoids in the immature leaf cushion and needles.

Animals↗
PubMed2002

Carbon exchange of an old-growth eastern hemlock (Tsuga canadensis) forest in central New England.

Carbon (C) exchange of an approximately 200-year-old eastern hemlock (Tsuga canadensis L.) forest in central Massachusetts, USA, was estimated from mid-October 2000 through October 2001 based on eddy covariance measurements and statistical modeling from microclimatic data. Measurements were made in 68% of the hours during the year of study, with > 50% coverage in all months except December and August. Data were filtered by wind direction and atmospheric turbulence to remove invalid measurements. Analysis of filtered data showed that photosynthetically active radiation (PAR) was significant in predicting C exchange, except during the winter. Daily minimum air temperature affected C exchange in autumn and winter, whereas time of day, water vapor pressure deficit and air temperature had significant effects on C storage in spring, summer and fall. Most C storage in the stand occurred in April through July and in October 2001, with maximum rates in April and May. Persistent cold weather prevented C storage in December through March. In early spring 2001, C uptake was sensitive to nocturnal frost: daily minimum air temperatures below 0 degrees C reduced C fixation, and minima below -5 degrees C caused its virtual cessation. Soil temperature was a poor predictor of C balance during this period. In August, high soil and air temperatures (averaging 16.7 and 21.1 degrees C, respectively) drove high ecosystem respiration, which approximately balanced C uptake. These patterns show potential for stimulated C storage in hemlock forests in a warmer climate with fewer spring and autumn frosts, but reduced C storage during warmer summers. Estimated annual C storage was 3.0 Mg ha(-1), which is higher than for younger coniferous and deciduous forests during earlier years in the northeastern USA. Long-term data are needed to determine if the estimated high C storage in this hemlock forest is a result of interannual climate variation or an effect of forest composition.

Biomass↗
PubMed2004

Feeding preference of three lady beetle predators of the hemlock woolly adelgid (Homoptera: Adelgidae).

In a laboratory study, we tested the feeding preferences of three coccinellid predators of hemlock woolly adelgid, Adelges tsugae Annand, an introduced pest of hemlock in the eastern United States. The species tested were Sasajiscymnus tsugae Sasaji & McClure (formerly Pseudoscymnus tsugae) from Japan, Scymnus ningshanensis Yu & Yao from China, and Harmonia axyridis (Pallas), a generalist species introduced from Asia that is currently widespread in eastern hemlock, Tsuga canadensis Carriere, forests. We measured the feeding preference of each beetle species when given the choice of A. tsugae and either 1) Pineus strobi (Hartig) on Pinus strobus L.; 2) Adelges laricis Vallot on Larix decidua Mill.; 3) Adelges cooleyi (Gillette) on Pseudotsuga menziesii (Mirb.) Franco; or 3) Paraprociphilus tessellatus (Fitch) on Alnus serrulata (Ait.) Willd. We evaluated beetle preference for adults, nymphs, and eggs of each prey species. Generally, when adult or nymphal prey stages were compared, S. tsugae preferred A. tsugae adults to P. strobi, A. cooleyi, A. laricis, and P. tessellatus. S. ningshanensis showed less preference between adelgid species, but it did not prefer P. tessellatus nymphs. When preferences for adelgid eggs were assayed, S. tsugae and S. ningshanensis showed no preference between A. tsugae and A. cooleyi or P. strobi, but S. tsugae did prefer A. tsugae to A. laricis. Larvae of S. tsugae were unable to survive on P. tessellatus nymphs. H. axyridis adults readily consumed both A. tsugae and P. tessellatus, but H. axyridis larvae did not complete their life cycle on A. tsugae. Our host range tests suggest that S. ningshanensis and S. tsugae may feed on several species of Adelgidae and that A. tsugae is often preferred.

Animals↗
PubMedDate not supplied

Ion cycling in hemlock-northern hardwood forests of the southern Lake Superior region: a preliminary study.

Upland forests of the southern Lake Superior region are diverse and contain a shifting mosaic of eastern hemlock [Tsuga canadensis (L.) Carr.] and northern hardwood forests dominated by sugar maple (Acer saccharum Marsh.). In this study, we survey the relative effects of management practice (old growth vs. managed), forest cover type (hemlock vs. northern hardwood), and soil great group (Entic Haplorthod vs. Alfic Oxyaquic Fragiorthod) on ion cycling as a precursor to a longer-term, more detailed study. Bulk precipitation, throughfall, and soil leachates at three depths were collected for two growing seasons in eight stands on the Ottawa National Forest in the Upper Peninsula of Michigan. A total of 1210 solutions were analyzed for pH, Na, K, Mg, Ca, Cl, NO3, and SO4. Losses of base cations (Ca, Mg, K) and SO4 from the bottom of the rooting zone generally were greater in old-growth than in managed northern hardwoods on both fragic and nonfragic soils. Leaching losses of base cations and NO3 usually were greater beneath old-growth northern hardwoods than beneath old-growth hemlock on both soil types and for both forest cover types and management practices on fragic than nonfragic soils. Management practice, forest cover type, and soil type all appear to affect ion cycling within these forests. All of the stands featured striking losses of base cations that probably are influenced strongly by NO3 and SO4 in atmospheric deposition.

Acer↗
PubMed1988

Radio ultrasound observations of the fetotoxic effects in sheep from ingestion of Conium maculatum (poison-hemlock).

Fetal movement in pregnant ewes gavaged with Conium maculatum (poison-hemlock) was reduced significantly, but temporarily. Fetal movement was observed by radio ultrasound at 45, 54 and 60 days of gestation in control ewes and on days 45, 54, and 60 of gestation immediately before and 1 hour following poison-hemlock feeding in treated ewes. Fetal movement was significantly reduced (P less than 0.01) 1 hour after poison-hemlock administration, but returned to normal within 18 hours post treatment. At parturition seven of eleven lambs born to seven treated ewes had varying degrees of front limb abnormalities. Modest to moderate flexure of the carpal joints, some lateral deviation in the front limbs at the pastern joint and kinked tails were observed. These malformations were transient and resolved spontaneously by 8 weeks after lambing.

Animals↗
PubMed2004

Poison hemlock (Conium maculatum L.).

One of the most poisonous species amongst higher plants is Conium maculatum. It is a very common nitrophile weed species, belonging to the Apiaceae (formerly Umbelliferae) family. It contains some piperidine alkaloids (coniine, N-methyl-coniine, conhydrine, pseudoconhydrine, gamma-coniceine), which are formed by the cyclisation of an eight-carbon chain derived from four acetate units. gamma-Coniceine is the precursor of the other hemlock alkaloids. All vegetative organs, flowers and fruits contain alkaloids. The concentrations (both absolute and relative) of the different alkaloids depend on plant varieties, on ecological conditions and on the age of the plant. The characteristic biological effects of the plants are summarised on cattle, sheep, goat, swine, rabbit, elk, birds and insects and the symptoms of the human toxicosis (some cases of poisonings) are discussed according to the literature data. The general symptoms of hemlock poisoning are effects on nervous system (stimulation followed by paralysis of motor nerve endings and CNS stimulation and later depression), vomiting, trembling, problems in movement, slow and weak later rapid pulse, rapid respiration, salivation, urination, nausea, convulsions, coma and death.

Animals↗
PubMed1997

Xylem cavitation and loss of hydraulic conductance in western hemlock following planting.

Following planting, western hemlock (Tsuga heterophylla (Raf.) Sarg.) seedlings experience water stress and declining xylem pressure potential (Psi(x)). Low Psi(x) can result in xylem cavitation and embolism formation, causing a decline in hydraulic conductance. This study focused on the relationship between Psi(x), xylem cavitation and transpiration (E) of newly planted seedlings. Leaf specific hydraulic conductance (k(AB)) declined from 0.56 to 0.09 mmol m(-2) s(-1) MPa(-1) over a 9-day period. Stomatal conductance (g(s)) declined from 143.5 to 39.15 mmol m(-2) s(-1) over the same period without an associated change in environmental conditions. A vulnerability profile indicated a 30% loss in hydraulic conductivity when seedlings experienced a Psi(x) between -2.5 and -3.0 MPa. A Psi(x) of -4.0 MPa led to a complete loss of conductivity. We conclude that following planting, western hemlock seedlings often experience Psi(x) values that are low enough to cause xylem cavitation and a decline in k(AB).

Journal Article↗
PubMed1992

Borrelia burgdorferi infection in white-footed mice (Peromyscus leucopus) in hemlock (Tsuga canadensis) habitat in western Pennsylvania.

White-footed mice (Peromyscus leucopus) were captured and their tissues sampled from 27 sites in seven counties of western Pennsylvania in 1990 for isolation and identification of Borrelia burgdorferi. Two hundred sixty mice were captured from which there were 27 isolations. Significantly more mice were captured and significantly more isolations made from hemlock (Tsuga canadensis) habitat than from deciduous species forest. Hemlock habitat is sparse and focal but evidently increases winter survival of mice, and thus possibly results in increased infection rates in mice.

Animals↗
PubMedDate not supplied

Conium maculatum (poison hemlock) toxicosis in a flock of range turkeys.

Five 20-week-old tom turkeys from a flock of range turkeys were presented for examination; the flock had a history of salivation, tremors, paralysis, and increased mortality. Necropsy revealed numerous seeds identified as seeds from Conium maculatum (poison hemlock) within the crop, proventriculus, and gizzard. Histopathologic alterations were limited to catarrhal enteritis. Clinical signs of Conium maculatum toxicosis abated after the turkeys were removed from their range, which was infested with poison hemlock.

Animals↗
PubMed1985

Congenital skeletal malformations induced by maternal ingestion of Conium maculatum (poison hemlock) in newborn pigs.

Skeletal malformations were induced in newborn pigs from gilts fed Conium maculatum seed or plant during gestation days 43 through 53 and 51 through 61. The teratogenic effects in groups dosed during gestation days 43 through 53 were more severe than those in groups dosed during the later period, with many newborn pigs showing arthrogryposis and twisted and malaligned bones in the limbs and with 1 pig showing scoliosis and deformity of the thoracic cage. The pigs born to gilts given C maculatum during gestation days 51 through 61 had excessive flexure primarily in the carpal joints, without scoliosis or bone malalignment in the limbs. The teratogenicity of poison hemlock depends on the alkaloid concentration and content. Based on the data presented, we speculate that gamma-coniceine is the teratogenic alkaloid in the poison hemlock fed to the gilts.

Abnormalities, Drug-Induced↗
PubMed2005

Hemlock alkaloids from Socrates to poison aloes.

Hemlock (Conium maculatum L. Umbelliferae) has long been known as a poisonous plant. Toxicity is due to a group of piperidine alkaloids of which the representative members are coniine and gamma-coniceine. The latter is the more toxic and is the first formed biosynthetically. Its levels in relation to coniine vary widely according to environmental conditions and to provenance of the plants. Surprisingly, these piperidine alkaloids have turned up in quite unrelated species in the monocotyledons as well as the dicotyledons. Aloes, for instance, important medicinal plants, are not regarded as poisonous although some species are very bitter. Nevertheless a small number of mostly local species contain the alkaloids, especially gamma-coniceine and there have been records of human poisoning. The compounds are recognized by their characteristic mousy smell. Both acute and chronic symptoms have been described. The compounds are neurotoxins and death results from respiratory failure, recalling the effects of curare. Chronic non-lethal ingestion by pregnant livestock leads to foetal malformation. Both acute and chronic toxicity are seen with stock in damp meadows and have been recorded as problems especially in North America. The alkaloids derive biosynthetically from acetate units via the polyketide pathway in contrast to other piperidine alkaloids which derive from lysine.

Alkaloids↗
PubMed2000

Exploring the structural basis of neurotoxicity in C(17)-polyacetylenes isolated from water hemlock.

Water hemlock, Cicuta virosa, belonging to the Umbelliferae, is well-known as a toxic plant responsible for lethal poisonings in humans as well as animals, causing tonic and clonic convulsions and respiratory paralysis. Cicutoxin (1), being a major violent toxin of the plant, is a chemical in the class of C(17)-polyacetylenes bearing a long pi-bond conjugation system, a terminal hydroxyl, and an allylic hydroxyl in its structure, and a variety of its analogues have been isolated from the plant. In the present study, various derivatives of these toxins were synthesized through acetylation, methylation, and oxidation of cicutoxin (1) and virol A (3) and B (4). 1-Dehydroxyvirol A (28) was prepared through the coupling of (7S)-dodeca-3,5-dien-1-yn-7-ol and 1-iodopentyne under Sonogashira's conditions. A monoacetylenic compound (29) was also prepared through the coupling of (5S)-1-chlorodeca-1,3-dien-5-ol and 1-iodopentyn-5-ol. The structure-activity relationships involved in the acute toxicity of cicutoxin derivatives in mice were investigated, and the length and geometry of pi-bond conjugation and the O-functional groups were found to be important for activity. The potency in inhibition of the specific binding of the noncompetitive GABA antagonist, [(3)H]EBOB, to GABA-gated Cl(-) channels of GABA receptors in rat brain cortex was found to be correlated with acute toxicity, indicating that the ability to bind to these channels plays an important role in the acute toxicity of these compounds.

Acetylene↗
PubMedDate not supplied

Who is fighting for the right to die? Older women's participation in the Hemlock Society.

Who is fighting for the right to die? Past literature has been mixed as to the membership of this social movement. In the current study, 6,398 Hemlock Society members were surveyed in an effort to answer questions concerning who is participating in the right to die movement, whether these participants are rapidly approaching their own death or reacting to the death of a loved one, and whether the movement is invigorated by singular activists. The findings indicate that older, white, wealthy, highly educated, economically and politically active women are in the forefront of the right to die movement. These women report currently being mentally and physically healthy, yet already having taken the steps that will allow them to have an element of control over their death. Finally, right to die support seems to be part of a larger collective network concerning health care and political policy issues.

Adult↗
PubMed1994

Hemlock: murder before the Lord.

Two healthy young men were killed by a plume of hemlock (Conium maculatum) emitted when contaminated incense was vaporized during religious rites about the middle of the thirteenth century BC.

Bible↗
PubMed2001

A fatal case of apparent water hemlock poisoning.

A 14-y-o North American native boy died 20 h after ingesting "wild carrot". He was gathering edible plants with his family on Canadian Thanksgiving. A sample of the plant he ingested couldn't be positively identified but it contained cicutoxin on chromatography. Bioassay caused death in mice which demonstrated clinical signs similar to water hemlock (Cicuta maculata) poisonings. Cicutoxin could not be demonstrated in postmortem tissue or gastric lavage. The boy's clinical signs and laboratory tests were consistent with other reported cases of this poisoning.

Adolescent↗
PubMed1979

A case of water hemlock poisoning.

Water hemlock is a ubiquitous plant that can be mistaken for a turnip as in the case reported. Oral ingestion causes an explosive illness consisting of nausea, vomiting, abdominal cramps, and grand mal seizures that can progress to cyanosis and death. In the reported case a 30-year old man was found semi-comatose some 75 minutes after ingesting a "turnip". The history revealed profuse emesis shortly after eating lunch that changed from bile to frank blood. There was a mean orthostatic blood pressure change of 30 torr, with an increase in the heart rate of 10%. Neurologic examination revealed a lethargic patient. Following administration of 4 liters of Ringer's lactate the patient's blood pressure stabilized and with continued isotonic fluid maintenance he improved rapidly. This case indicates that appropriate management should be directed toward protecting the patient's airway from gastric aspiration, restoring the intravascular and extracellular volume deficit, and controlling cerebral edema.

Adult↗
PubMed2006

A case study: looking at the effects of fragmentation on genetic structure in different life history stages of old-growth mountain hemlock (Tsuga mertensiana).

We examined fine-scale genetic structure of mountain hemlock (Tsuga mertensiana) in an old-growth stand and an adjacent seedling population, with the goal of detecting the effects of fragmentation. Three hundred and six old-growth trees and 195 naturally regenerating seedlings were genotyped at 5 microsatellite loci. Genetic diversity was similar across old-growth life stages and within the clear-cut seedlings. Significant inbreeding was found in the adult class (30+ cm diameter at breast height) of old-growth seedlings and in the adjacent natural regeneration. Relatedness was significantly associated with physical distance for both the oldest age class and for regenerating seedlings in the adjacent clear-cut, whereas intermediate classes showed no such association. As intermediate classes show no isolation by distance, the associations that arise probably occur from single cohort regeneration that clearly has taken place in the clear-cut, and possibly when the oldest old-growth trees were established. Parentage analysis suggested that large-scale fragmentation, such as this clear-cut, allowed for increased long-distance seed dispersal. We conclude that long-lived tree populations can consist of a cohort mosaic, reflecting the effects of fragmentation, and resulting in a complex, age-dependent, local population structure with high levels of genetic diversity.

Aging↗