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1.
Orthocoelium serpenticaecum n. sp. is described and illustrated from specimens collected from the swamp buffalo (Bubalus bubalis Linnaeus) in the Philippines. It is readily distinguished from all species of the genus by the tortuous dorso-ventral bends
of the caeca and the different types of pharynx and terminal genitalium which are described as ‘serpenticaecum types’ (new
types).
Supported by a research grant (No. 8301 Ag) from the National Science and Technology Authority (NSTA) Assisted University
of the Philippines System (UPS) Integrated Research Program. 相似文献
2.
The structural and functional interrelationships of muscarinic acetylcholine receptor subtypes 总被引:1,自引:0,他引:1
J Ramachandran E G Peralta A Ashkenazi J W Winslow D J Capon 《BioEssays : news and reviews in molecular, cellular and developmental biology》1989,10(2-3):54-57
Molecular cloning of the genes encoding the muscarinic acetylcholine receptors has shown that receptor subtypes classified on the basis of pharmacological properties are related polypeptides encoded by distinct genes. These studies have also revealed the existence of novel muscarinic receptor subtypes. Functional analysis of each of the subtypes expressed in mammalian cells indicates that the different subtypes activate distinct biochemical pathways, a finding that explains the tissue-specific physiological response elicited by the neurotransmitter, acetylcholine. 相似文献
3.
4.
Summary A combination of two monoclonal antibodies and high resolution immunocytochemical technique was applied to label estrogen receptors in spontaneous mouse mammary tumors. Protein A-colloidal gold complex was used as an electron opaque marker. With this procedure estrogen receptors were labelled in the nuclei of cancer cells, predominantly over heterochromatin. In the cytoplasm a slight tagging of the rough endoplasmic reticulum was detected, apparently related with the sites of receptor biosynthesis. Other organelles and the mammary tumor viruses (MuMTV) were not stained immunocytochemically.The immunocytochemical procedure applied in this investigation allowed the detection of low levels of estrogen receptors in an estrogen-unresponsive mammary carcinoma. The presence of estrogen receptors with a specific distribution in estrogen-independent tumors suggests the need of a reevaluation of their capacity as indicators of hormone-dependence in mammary carcinomas. 相似文献
5.
Distinct sequence elements control the specificity of G protein activation by muscarinic acetylcholine receptor subtypes. 总被引:25,自引:5,他引:20 下载免费PDF全文
J Lechleiter R Hellmiss K Duerson D Ennulat N David D Clapham E Peralta 《The EMBO journal》1990,9(13):4381-4390
Relatively little is understood concerning the mechanisms by which subtypes of receptors, G proteins and effector enzymes interact to transduce specific signals. Through expression of normal, hybrid and deletion mutant receptors in Xenopus oocytes, we determined the G protein coupling characteristics of the functionally distinct m2 and m3 muscarinic acetylcholine receptor (mAChR) subtypes and identified the critical receptor sequences responsible for G protein specificity. Activation of a pertussis toxin insensitive G protein pathway, leading to a rapid and transient release of intracellular Ca2+ characteristic of the m3 receptor, could be specified by the transfer of as few as nine amino acids from the m3 to the m2 receptor. In a reciprocal manner, transfer of no more than 21 residues from the m2 to the m3 receptor was sufficient to specify activation of a pertussis toxin sensitive G protein coupled to a slow and oscillatory Ca2+ release pathway typical of the m2 subtype. Notably, these critical residues occur within the same region of the third cytoplasmic domain of functionally distinct mAChR subtypes. 相似文献
6.
Forty-one isolates ofFusarium obtained from the main Argentinian corn production area were tested for their ability to produce moniliformin. One of 22 isolates ofF. moniliforme, 2/10 of F.proliferatum and 3/9 ofF. subglutinans, produced moniliformin in a range between 0,3 to 2,7 mg/g. These data represent the first report of the production of moniliformin byFusarium species from section Liseola in Argentina. 相似文献
7.
The ATP-binding-cassette transmembrane transporters (ABC transporters)
known from vertebrates belong to four major subfamilies: (1) the P-
glycoproteins (Pgp); (2) the cystic fibrosis transmembrane conductance
regulators (CFTR); (3) the Tap proteins encoded with the major
histocompatibility complex of mammals; and (4) the peroxisomal membrane
proteins. Both Pgp and CFTR have a structure suggesting a past internal
gene duplication; a phylogenetic analysis indicated that these duplications
occurred independently, while an independent tandem gene duplication
occurred in the case of the Tap family. Both the Pgp and Tap proteins show
evidence of relationship to bacterial ABC transporters lacking internal
duplication, and both are significantly more closely related to the HlyB
and MsbA families of transporters from purple bacteria than they are to ABC
transporters from nonpurple bacteria. The simplest hypothesis to explain
this observation is that eukaryotic Pgp and Tap genes are descended from a
mitochondrial gene or genes that were subsequently translocated to the
nuclear genome. The Pgp genes of eukaryotes are characterized by a
remarkable degree of convergent evolution between the ATP-binding cassettes
of their N- terminal and C-terminal halves, whereas no such convergence is
seen between the two halves of CFTR genes or between the duplicated Tap
genes. Exon 13 of the CFTR gene, which encodes a putative regulatory domain
not found in other ABC transporters apart from CFTR, showed high levels of
both synonymous and nonsynonymous difference in comparisons among different
mammalian species, suggesting that this region is a mutational hot spot.
相似文献
8.
9.
X Xiao G Hintermann AL Demanin J Piret 《Journal of industrial microbiology & biotechnology》1996,16(4):261-262
Streptomyces glaucescens is shown to possess -lactamase activity which is inhibitable by clavulanate. This is important in regard to its use as a cloning host for enzymes of \-lactam biosynthesis. 相似文献
10.
Ignacio Hernndez Gloria Peralta J. Lucas Prez-Llorns Juan J. Vergara F. Xavier Niell 《Journal of phycology》1997,33(5):764-772
During the last decade, the Palmones River estuary has undergone severe eutrophication followed by a green tide episode; two species of Ulva, rotundata Blid. and Ulva curvata (Kütz.) De Toni, were the main macroalgae responsible for this bloom. From November 1993 to December 1994, we followed the biomass, the growth dynamics, and tissue elemental composition (C:N:P)of Ulva species, as well as some physicochemical variables in the estuary. Maximum biomass (up to 375 g dry wt·m?2 in some spots, corresponding to a thallus area index of nearly 17 m2Ulva·m?2 sediment) were observed in June and December. However, the biomass varied among the sampling stations. Water nitrate, ammonia, and phosphate showed high concentrations throughout the year, with extremely high transient pulses, sustaining the high growth rates observed. Growth rates were estimated directly in the field. The rates were generally higher in Ulva discs maintained in net cages than those estimated by changes in biomass standing stock between two consecutive samplings. The difference between both estimates was used to quantify the importance of the processes causing loss of biomass, which were attributable to grazing, exported biomass, and thallus decomposition under anaerobic conditions resulting from extreme self-shading. Maximum chlorophyll content was found in winter, whereas the minimum was in spring. Atomic N:P ratios were generally higher in the algae than in the water. However, the absolute concentrations of tissue N and P were always higher than the critical levels for maximum growth, which suggests that growth was not limited by inorganic N or P availability. The results suggested that the increase in nutrient loading in the river may have triggered the massive development of green algae and that light limitation and temperature stress in summer seem to be the main factors controlling the abundance of Ulva in the estuary. In addition to light availability and thermal stress, the different loss processes may have a decisive role in the dynamics of Ulva biomass. 相似文献