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71.
Intraspecific variation in the maximum shell length of Pisidium is small in comparison with variation in the life span of the clams, from 4 mo to 4 yr. The use of shell length as a measure of size is complicated by large intraspecific variation in the weight-length relationship, a possible reflection of resource availability on the weight of the soft parts. Maximum embryo length is relatively constant (1 mm) in the majority of species but litter size is variable (1 to 40), generally increasing with parent size. The time of egg-laying is determined by the size of the clam, season, and previous episode of reproduction, while the timing of the release of embryos, depending also on embryonic growth rate, is additionally affected by temperature and oxygen conditions. In brief, the maximum adult and embryo lengths are relatively conservative traits while growth rates vary by an order of magnitude.
Reproductive effort, when measured by the ratio of litter weight to parent weight, may increase or decrease with parent length and age. Both semelparous and iteroparous populations are known in several species. We suggest that if maximum adult length can be reached by the first reproductive season (in a favourable environment) the population is semelparous, otherwise (in an unfavourable environment) the population is iteroparous. Gravid clams in semelparous populations continue to grow, and thus assimilation cannot be meaningfully partitioned into reproduction, somatic growth and maintenance.
Along a depth gradient from 8 to 65 m, maximum and mature shell lengths, embryo length and litter size varies significantly in Pisidium conventus subpopulations not distinguishable electrophoretically. Large clams in deep water produce large embryos but small litters, which is contrary to the general trend of increasing litter size with parent length. Low food availability that decreases juvenile growth rate may restrict litter size in this case. 相似文献
Reproductive effort, when measured by the ratio of litter weight to parent weight, may increase or decrease with parent length and age. Both semelparous and iteroparous populations are known in several species. We suggest that if maximum adult length can be reached by the first reproductive season (in a favourable environment) the population is semelparous, otherwise (in an unfavourable environment) the population is iteroparous. Gravid clams in semelparous populations continue to grow, and thus assimilation cannot be meaningfully partitioned into reproduction, somatic growth and maintenance.
Along a depth gradient from 8 to 65 m, maximum and mature shell lengths, embryo length and litter size varies significantly in Pisidium conventus subpopulations not distinguishable electrophoretically. Large clams in deep water produce large embryos but small litters, which is contrary to the general trend of increasing litter size with parent length. Low food availability that decreases juvenile growth rate may restrict litter size in this case. 相似文献
72.
Hans Gustafsson Ismo Virtanen Lars-Eric Thornell 《Virchows Archiv. B, Cell pathology including molecular pathology》1989,57(1):303-313
The presence of intermediate filament proteins (IFP) in normal salivary gland tissue and in a number of salivary gland neoplasms
has been investigated by immunohistochemical techniques on frozen sections. Cytokeratins (CKs) were seen in almost all normal
epithelial cells. In the parotid gland and in palatal gland tissue, a co-expression of cytokeratin and glial fibrillary acidic
protein (GFAP) was seen in some myoepithelial cells, but this was not apparent in the submandibular gland. In some pleomorphic
adenomas, carcinomas in pleomorphic adenomas, one mucoepidermoid carcinoma, one mucus-producing adenopapillary carcinoma and
one adenoid cystic carcinoma, cells expressing three different IFP classes were found (CKs, vimentin, GFAP). These cells were
most often situated peripherally in the tumour cords or ducts. The cytokeratin pattern in these cells, as revealed by mAbs
PKK1-3, was similar to that in normal myoepithelial cells. Furthermore, reactivity for a fourth class of IFP, desmin, could
be seen in this cell type in two carcinomas in pleomorphic adenomas, and also in a few cells in a pleomorphic adenoma and
an adenoid cystic carcinoma. Thus the pattern of IFP expression in salivary gland neoplasms, is very complex, and cannot always
be related to the normal tissue. 相似文献
73.
Niall Glanville Ismo Ulmanen 《Biochemical and biophysical research communications》1976,71(1):393-399
Cell-free translation of the Semliki Forest virus-specific 26S RNA yielded primarily capsid protein. After treatment of the protein synthesising reaction with 25 mM EDTA, the capsid protein cosedimented with the large ribosomal subunit in sucrose gradients, and banded with the subunit at a density of 1.54 gm/cm3 in CsCl. Exposure to 0.5 M KCl released the protein from the subunit. Similar binding of the virus capsid protein to the large ribosomal subunit has been observed in infected HeLa cells, although its function is not clear. The nonstructural proteins, which are the major products translated from the virion 42S RNA, did not associate with sedimenting structures. 相似文献
74.
Pia Lautala Ismo Ulmanen Jyrki Taskinen 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1999,736(1-2)
A new chromatographic catechol O-methyltransferase (COMT) assay based on S-adenosyl-
-[methyl-14C]methionine and on-line radioactivity detection was developed. With minor modifications in the mobile phase composition the methylation velocities for 30 structurally diverse compounds including simple catechols, neurotransmitters, catecholestrogens and catecholic drugs could be measured using human and rat recombinant soluble COMT. The enzymes showed very similar substrate selectivities. The radiochemical method was validated using 3,4-dihydroxybenzoic acid as a model substrate and it was shown that accurate and reproducible methylation velocity values could be achieved for both of the catecholic hydroxyls. The method proved to be suited for determining the enzyme kinetic parameters and can probably be further used for gathering enzyme kinetic data on differentially substituted catechols in order to construct proper structure-activity relationships for COMT. 相似文献
75.
Merja H. Niemi Timo Pulli Matti Höyhtyä Juha Rouvinen Kristiina Takkinen 《Journal of molecular biology》2010,400(4):803-814
(−)-Δ9-Tetrahydrocannabinol (THC) is the main psychoactive compound found in cannabis. In this study, an anti-THC Fab fragment, designed T3, was isolated from a display library cloned from the spleen cells of a mouse immunized with a THC-bovine serum albumin conjugate, and the crystal structures of the T3 Fab in its free form and in complex with THC were determined at 1.9 Å and 2.0 Å resolution, respectively. The THC binding site of the T3 Fab is a narrow cavity: the n-pentyl group of THC protrudes deep into the interface area between the variable domains and the C10 monoterpene moiety of the hapten is partially exposed to solvent. The metabolites of THC, with modifications in the C10 monoterpene moiety, 11-nor-9-carboxy-Δ9-tetrahydrocannabinol and 11-hydroxy-Δ9-tetrahydrocannabinol, are bound by the T3 Fab with a higher affinity than THC. The crystal structures suggest that Ser52H and Arg53H of the T3 Fab are able to make hydrogen bonds with the metabolites, which leads to an increased binding against these metabolites. By developing a T3 Fab-Δ9-THC immunocomplex binding antibody from a naïve antibody phage display library, the specificity of the Δ9-THC binding is highly increased, which allows a one-step, homogeneous, fluorescence resonance energy transfer-based sensitive immunoassay, with a detection limit of 20 ng/ml from saliva samples. 相似文献
76.
77.
78.
Ariel Noro Tarvo Sillat Ismo Virtanen Sulev Ingerpuu Nils B?ck Yrj? T. Konttinen Matti Korhonen 《The journal of histochemistry and cytochemistry》2013,61(10):719-730
The aim was to study laminin (LM) synthesis, integration, and deposition into the basement membrane (BM) during adipogenesis. Human bone marrow-derived mesenchymal stromal cells (MSCs) were induced along the adipogenic lineage. LM chain mRNA and protein levels were followed using quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence (IF) staining, transmission electron microscopy (TEM), and immunoprecipitation. MSCs produced low levels of LM mRNAs but were not surrounded by BM in IF and TEM imaging. LM-α4, LM-β1, and LM-γ1 mRNAs increased during adipogenesis 3.9-, 5.8-, and 2.8-fold by day 28. LM-411 was immunoprecipitated from the ECM of the differentiated cells. Immunostaining suggested deposition of LM-411 and some LM-421. BM build-up was probably organized in part by integrin (Int) α6β1. At day 28, TEM images revealed BM-like structures around fat droplet-containing cells. The first signs of BM formation and Int α6β1 were seen using IF imaging at day 14. Laminin-411 and Int α6β1 were expressed in vivo in mature human subcutaneous fat tissue. Undifferentiated human MSCs did not organize LM subunits into BM, whereas LM-411 and some LM-421 are precipitated in the BM around adipocytes. This is the first demonstration of LM-411 precipitation during hMSC adipogenesis around adipocytes as a structural scaffold and Int-regulated signaling element. 相似文献
79.
Laccases catalyze the oxidation of phenolic substrates and the concominant reduction of dioxygen to water. We used xenon as an oxygen probe in search of routes for the entry of dioxygen into the catalytic center. Two xenon-pressurized crystal structures of recombinant Melanocarpus albomyces laccase were determined, showing three hydrophobic Xe-binding sites located in domain C. The analysis of hydrophobic cavities in other laccase structures further suggested the preference of domain C for binding of hydrophobic species such as dioxygen, thus suggesting that the hydrophobic core of domain C could function as a channel through which dioxygen can enter the trinuclear copper center. 相似文献
80.
Parkkinen T Boer H Jänis J Andberg M Penttilä M Koivula A Rouvinen J 《The Journal of biological chemistry》2011,286(31):27294-27300
Uronate dehydrogenase from Agrobacterium tumefaciens (AtUdh) belongs to the short-chain dehydrogenase/reductase superfamily and catalyzes the oxidation of D-galacturonic acid and D-glucuronic acid with NAD(+) as a cofactor. We have determined the crystal structures of an apo-form of AtUdh, a ternary form in complex with NADH and product (substrate-soaked structure), and an inactive Y136A mutant in complex with NAD(+). The crystal structures suggest AtUdh to be a homohexamer, which has also been observed to be the major form in solution. The monomer contains a Rossmann fold, essential for nucleotide binding and a common feature of the short-chain dehydrogenase/reductase family enzymes. The ternary complex structure reveals a product, D-galactaro-1,5-lactone, which is bound above the nicotinamide ring. This product rearranges in solution to D-galactaro-1,4-lactone as verified by mass spectrometry analysis, which agrees with our previous NMR study. The crystal structure of the mutant with the catalytic residue Tyr-136 substituted with alanine shows changes in the position of Ile-74 and Ser-75. This probably altered the binding of the nicotinamide end of NAD(+), which was not visible in the electron density map. The structures presented provide novel insights into cofactor and substrate binding and the reaction mechanism of AtUdh. This information can be applied to the design of efficient microbial conversion of D-galacturonic acid-based waste materials. 相似文献