黑腹菌属二新种(英文)

本文报道了中国产的黑腹菌属Melanogaster(黑腹菌科 Melanogastraceae,黑腹菌目 Melanogastrales,担子菌亚门Basidiomycotina)二新种:山西黑腹菌Melanogaster shanxicnsis Liu,K.Tao et Chang和倒卵孢黑腹菌M.obouatisporus Liu,K.Tao et Chang并对中国已报道过的黑腹菌属内的种进行了讨论。     

Differential cardiovascular effects mediated by mu and kappa opiate receptors in hindbrain nuclei

To further investigate the role of opioid peptides and specific opiate receptor subtypes in central cardiovascular regulation by hindbrain nuclei, mu (D-Ala²,MePhe⁴,Gly-ol⁵ enkephalin, DAGO), delta (D-Ala²,D-Leu⁵ enkephalin, DADL) or kappa (MRZ 2549) agonists were microinjected into hindbrain nuclei of spontaneously or artificially respired, pentobarbital-anesthetized rats. In the nucleus tractus solitarius (NTS), DAGO and DADL (0.3 nmol) elicited pressor responses and tachycardia. MRZ (3.0–16 nmol) depressed blood pressure in spontaneously breathing rats, but accelerated heart rate in artificially ventilated animals. Blood pressure and heart rate of spontaneously breathing animals were not altered following nucleus ambiguus (NA) injection of DAGO or DADL (0.3 nmol), but were elevated in artificially respired animals; MRZ (3.0–10 nmol) injected into the NA depressed blood pressure in both groups. These data suggest that in the absence of respiratory depression, NTS and NA mu receptors mediate pressor responses and tachycardia; kappa receptors in the NA mediate a decrease in blood pressure but cardioacceleration in the NTS.     

Toxicity of cypermethrin: hsp70 as a biomarker of response in transgenic Drosophila

Heat shock protein induction is often associated with a cellular response to a harmful environment or to adverse life conditions. The main aims of our study were (1) to evaluate the cytotoxic potential of cypermethrin; and (2) to investigate the suitability of stress-induced heat shock protein Hsp70 as a biomarker for environmental pollutants in transgenic Drosophila melanogaster (Hsp70-lacZ)Bg⁹. Different concentrations of cypermethrin (0.002, 0.2, 0.5 and 50.0 p.p.m.) were mixed with food. Third instar larvae of transgenic Drosophila melanogaster were allowed to feed on these mixtures for different time intervals (2, 4, 6, 12, 24 and 48h). Following feeding, hsp70 induction and tissue damage were evaluated. In the highest concentration treatment group (50 p.p.m.), 100% larval mortality was recorded after 12 h exposure. Hsp70 was found to be induced even at the lowest concentration (0.002 p.p.m.) of the insecticide, while tissue damage was observed in the larvae exposed for 48 h. While an insignificant decline in hsp70 expression was observed in the larvae exposed to cypermethrin at a dietary concentration of 0.002 p.p.m. after 48 h compared with those exposed for 24 h, in the next two higher concentrations of the toxicant, a similar but significant decline in hsp70 expression was evident in the exposed larvae after 48 h. The present study reveals the cytotoxic potential of cypermethrin and further proposes that hsp70 induction in transgenic Drosophila melanogaster could be used as a sensitive biomarker in risk assessment.     

Phylogenetic incongruence in the Drosophila melanogaster species group

Drosophila melanogaster and its close relatives are used extensively in comparative biology. Despite the importance of phylogenetic information for such studies, relationships between some melanogaster species group members are unclear due to conflicting phylogenetic signals at different loci. In this study, we use twelve nuclear loci (eleven coding and one non-coding) to assess the degree of phylogenetic incongruence in this model system. We focus on two nodes: (1) the node joining the Drosophila erecta-Drosophila orena, Drosophila melanogaster-Drosophila simulans, and Drosophila yakuba-Drosophila teissieri lineages, and (2) the node joining the lineages leading to the melanogaster, takahashii, and eugracilis subgroups. We find limited evidence for incongruence at the first node; our data, as well as those of several previous studies, strongly support monophyly of a clade consisting of D. erecta-D. orena and D. yakuba-D. teissieri. By contrast, using likelihood based tests of congruence, we find robust evidence for topological incongruence at the second node. Different loci support different relationships among the melanogaster, takahashii, and eugracilis subgroups, and the observed incongruence is not easily attributable to homoplasy, non-equilibrium base composition, or positive selection on a subset of loci. We argue that lineage sorting in the common ancestor of these three subgroups is the most plausible explanation for our observations. Such lineage sorting may lead to biased estimation of tree topology and evolutionary rates, and may confound inferences of positive selection.     

Autonomic control of heart rate is virtually independent of temperature but seems related to the neuroanatomy of the efferent vagal supply to the heart in the bullfrog, Lithobathes catesbeianus

Bullfrogs, Lithobathes catesbeianus, bearing a femoral artery cannula were held at 3 temperatures (10, 20 and 30 °C) for 24 h. Changes in heart rate were recorded before and after injection of cholinergic and adrenergic antagonists. Normal heart rate doubled for each temperature increment. Adrenergic tone on the heart varied around 20% at all 3 temperatures but cholinergic tone increased from −5% to 10% between 10 and 30 °C. In contrast, cholinergic tone increased from 75% at 5 °C to 329% at 25 °C in Xenopus laevis. Injection of the neural tracer True Blue into the cervical vagus of the bullfrog revealed a single location for vagal preganglionic neurons (VPN) in the dorsal vagal motor nucleus (DVN), while Xenopus had 30% of its VPN in a ventro-lateral group outside the DVN. Broader comparative studies have suggested that differences in the extent of vagal tone may relate to the location of VPN in the brainstem and this may be the case in these amphibians.     

Field performance in northern Spain of Douglas-fir seedlings Inoculated with ectomycorrhizal fungi

 Experimental plantations were established in northern Spain to determine the effects of different ectomycorrhizal fungi on growth and survival of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) under field conditions. Douglas-fir seedlings were inoculated with Laccaria bicolor S238 mycelia in two bareroot nurseries in central France or with spore suspensions of three hypogeous ectomycorrhizal species: Melanogaster ambiguus, Rhizopogon colossus and R. subareolatus, in a Spanish containerised nursery. The effects of ectomycorrhizal inoculation on plant survival after outplanting were limited, being only significant at the Guipuzkoan (Spain) site, when plants inoculated with L. bicolor S238 were compared to non-inoculated plants grown in non-fumigated soil. L. bicolor S238 had a significant effect on plant growth during the phase of bareroot nursery growth and this difference was maintained after field outplanting. Nursery inoculations with M. ambiguus, R. colossus and R. subareolatus improved plant growth during the first 2 and 3 years after field outplanting. The positive effects of the inoculation treatment on seedling height, root collar diameter and stem volume persisted after 5 years of field growth. Inoculation with these ectomycorrhizal fungi may improve the field performance of Douglas-fir seedlings in northern Spain. Accepted: 12 February 1999     

Evidence that BDNF regulates heart rate by a mechanism involving increased brainstem parasympathetic neuron excitability

Autonomic control of heart rate is mediated by cardioinhibitory parasympathetic cholinergic neurons located in the brainstem and stimulatory sympathetic noradrenergic neurons. During embryonic development the survival and cholinergic phenotype of brainstem autonomic neurons is promoted by brain‐derived neurotrophic factor (BDNF). We now provide evidence that BDNF regulates heart rate by a mechanism involving increased brainstem cardioinhibitory parasympathetic activity. Mice with a BDNF haploinsufficiency exhibit elevated resting heart rate, and infusion of BDNF intracerebroventricularly reduces heart rate in both wild‐type and BDNF+/? mice. The atropine‐induced elevation of heart rate is diminished in BDNF+/? mice and is restored by BDNF infusion, whereas the atenolol‐induced decrease in heart rate is unaffected by BDNF levels, suggesting that BDNF signaling enhances parasympathetic tone which is diminished with BDNF haploinsufficiency. Whole‐cell recordings from pre‐motor cholinergic cardioinhibitory vagal neurons in the nucleus ambiguus indicate that BDNF haploinsufficiency reduces cardioinhibitory vagal neuron activity by increased inhibitory GABAergic and diminished excitatory glutamatergic neurotransmission to these neurons. Our findings reveal a previously unknown role for BDNF in the control of heart rate by a mechanism involving increased activation of brainstem cholinergic parasympathetic neurons

     

兴奋性氨基酸介导的膜电流可被吗啡阻断

在Ｓｐｒａｙｕｅ－Ｄａｗｉｅｙ大鼠的含有孤束核中央亚核及疑核神经元密集区的脑薄片上,吗啡（３—５ｐｍｏｌ）对疑核细胞内记录到的自发兴奋性突触后电位有抑制作用;向灌流液内注入吗啡可使电刺激孤束核在疑核记录到的兴奋性突触后电位的幅度降低７１．１±６．２％（Ｐ＜Ｏ．００１）,纳洛酮（５０ｎｍｏｌ／Ｌ）可翻转这种抑制效应;含有１０μｍｏｌ／Ｌ吗啡的灌流液对ＮＭＤＡ（０．５—１ｐｍｏｌ）、乙酰胆碱（３ｐｍｏｌ）及ＱＵｉｓｑｕａｌａｔｅ（０．１—０．５ｐｍｏｌ）引起的细胞膜去极化有不同程度的抑制作用,分别为３８．１±５．７％（Ｐ＜０．００１）,３２．８±５．５％（Ｐ＜０．０１）和２９．６±７．１％（Ｐ＜０．０５）。这些结果可能是由于吗啡兴奋μ和δ受体后,增加了Ｋ＋电流而降低Ｎａ＋,Ｃａ２＋离子通透性的缘故。     

Inoculation of containerized Pseudotsuga menziesii and Pinus pinaster seedlings with spores of five species of ectomycorrhizal fungi

 Container-grown Pseudotsuga menziesii and Pinus pinaster seedlings were inoculated with water suspensions of spores of five ectomycorrhizal fungi commonly found in northeastern Spain. Pseudotsuga menziesii seedlings were inoculated with basidiospores of Melanogaster ambiguus, or Rhizopogon subareolatus, or with ascospores of Tuber maculatum. Pinus pinaster seedlings were inoculated with basidiospores of Melanogaster ambiguus, Rhizopogon roseolus or Scleroderma citrinum. The spore concentrations were 10²–10⁷ spores per seedling for Melanogaster ambiguus (in Pseu dotsuga menziesii) and Rhizopogon subareolatus, 10³–10⁷ for Melanogaster ambiguus (in Pinus pinaster), Rhizopogon roseolus, and Scleroderma citrinum, and 10²–10⁴ for Tuber maculatum. Melanogaster ambiguus colonized more short roots in a larger proportion of plants at 10⁷ spores per seedling than at any other rate. The highest colonization by Rhizopogon subareolatus was obtained at 10⁴ spores per seedling and higher, and all inoculated plants became infected at 10⁶ spores per seedling and higher. Tuber maculatum colonized a high percentage of short roots at all rates tested; the proportion of infected plants was over 80% at 10³–10⁴ spores per plant, decreasing to 50% at 10² spores per plant. Rhizopogon roseolus colonized the highest number of short roots on nearly all the inoculated plants when applied at 10⁵ spores per seedling and higher. Scleroderma citrinum colonized a high percentage of short roots on all inoculated plants when applied at 10⁵ spores per seedling and higher. The abundance of sporocarps of Melanogaster ambiguus, Rhizopogon subareolatus, R hizopogon roseolus and Scleroderma citrinum and their colonization ability at relatively low rates allows these spores to be used as ectomycorrhizal inocula on a large scale. Accepted: 27 February 1996     

黑腹菌属二新种

本文报道了中国产的黑腹菌属Melanogaster(黑腹菌科 Melanogastraceae,黑腹菌目 Melanogastrales,担子菌亚门Basidiomycotina)二新种:山西黑腹菌Melanogaster shanxicnsis Liu,K.Tao et Chang和倒卵孢黑腹菌M.obouatisporus Liu,K.Tao et Chang并对中国已报道过的黑腹菌属内的种进行了讨论。