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101.
A flow-through viscometer is described, developed for application as a sensor in automated analysis. Its essential part is a glass capillary connected to the sample flow circuit with thin-walled rubber tubes at both ends. These tubes separate the fluid to be tested from a hydraulic liquid. This construction ensures the absence of dead space and a minimal test volume The usefulness of the apparatus is demonstrated in the automated assay of protease, amylase, and pectinase activity. Development of a mathematical model describing the enzymic degradation of macromolecules resulted in a reciprocal equation allowing rectilinear presentation of the calibration data. The feasibility of this model was tested by linear regression analysis of the data. 相似文献
102.
Introduction
To elucidate in polymyalgia rheumatica (PMR) the role of tumor necrosis factor (TNF) α and the therapeutic potential of blockade with soluble TNF-α receptor, we carried out the first randomized controlled trial with etanercept in PMR. 相似文献103.
Developmental Phenotypic Landscapes 总被引:1,自引:1,他引:0
H. Frederik Nijhout 《Evolutionary biology》2008,35(2):100-103
104.
Coexistence of novel gammaproteobacterial and Arsenophonus symbionts in the scale insect Greenisca brachypodii (Hemiptera,Coccomorpha: Eriococcidae) 下载免费PDF全文
Anna Michalik Frederik Schulz Katarzyna Michalik Florian Wascher Matthias Horn Teresa Szklarzewicz 《Environmental microbiology》2018,20(3):1148-1157
Scale insects are commonly associated with obligate, intracellular microorganisms which play important roles in complementing their hosts with essential nutrients. Here we characterized the symbiotic system of Greenisca brachypodii, a member of the family Eriococcidae. Histological and ultrastructural analyses have indicated that G. brachypodii is stably associated with coccoid and rod‐shaped bacteria. Phylogenetic analyses have revealed that the coccoid bacteria represent a sister group to the secondary symbiont of the mealybug Melanococcus albizziae, whereas the rod‐shaped symbionts are close relatives of Arsenophonus symbionts in insects – to our knowledge, this is the first report of the presence of Arsenophonus bacterium in scale insects. As a comparison of 16S and 23S rRNA genes sequences of the G. brachypodii coccoid symbiont with other gammaprotebacterial sequences showed only low similarity (~90%), we propose the name ‘Candidatus Kotejella greeniscae’ for its tentative classification. Both symbionts are transovarially transmitted from one generation to the next. The infection takes place in the neck region of the ovariole. The bacteria migrate between follicular cells, as well as through the cytoplasm of those cells to the perivitelline space, where they form a characteristic ‘symbiont ball’. Our findings provide evidence for a polyphyletic origin of symbionts of Eriococcidae. 相似文献
105.
H.Frederik Nijhout 《Journal of insect physiology》1979,25(3):277-281
Fifth instar nymphs of Oncopeltus fasciatus initiate a moulting cycle when they reach a critical weight of 27.9±1.1 (±S.D.) mg for females or 23.7±1.2 mg for males. This critical weight is not absolute. Its precise value depends on the somatic size of the individual. Large-bodied individuals have a higher critical weight than small-bodied ones. Sexual size-dimorphism accounts largely for sex differences in critical weights. Animals of a subcritical weight can be induced to moult by means of a saline injection, in the absence of further food intake or growth. Since a saline injection only stretches the abdominal wall it is suggested that moulting in Oncopeltus is triggered by stimulation of abdominal stretch receptors, as in bloodsucking Reduviidae. The critical weight is thus an index of the size at which a critical degree of stretch is achieved. 相似文献
106.
Preparation of deacylated phosphoglycerides 总被引:1,自引:0,他引:1
O-(sn-glycero-3-phosphoryl) ethanolamine and O-(sn-glycero-3-phosphoryl) choline can conveniently be isolated on a preparative scale from egg-yolk powder or soybean phospholipids by the following procedure:
- 1.
- 1.|Mild-alkaline methanolysis of the lipids. 相似文献
107.
108.
109.
Bert W Leliaert F Vierstraete AR Vanfleteren JR Borgonie G 《Molecular phylogenetics and evolution》2008,48(2):728-744
Tylenchina are a morphologically and functionally diverse group of nematode species that range from free-living bacteriovores, over transitory grazing root-hair feeders to highly specialized plant-parasites with complex host associations. We performed phylogenetic analyses of small subunit rDNA sequences from 97 species including an analysis that account for the RNA secondary structure in the models of evolution. The present study confirms the sister relationship of the bacteriovore Cephalobidae with the predominantly plant-parasitic Tylenchomorpha. All analyses appoint the fungal-feeding Aphelenchidae and Aphelenchoididae as being polyphyletic but the morphology based hypothesis of their monophyly could not be significantly rejected. Within the Tylenchomorpha, the families that exclusively parasitize higher plants are joined in a single clade. However, only the monophyletic position of the (super)families Hoplolaimidae and Criconematoidea were supported; Anguinidae, Tylenchidae, Belonolaimidae and Pratylenchidae appeared to be paraphyletic or polyphyletic. Parsimony and likelihood ancestral state reconstruction revealed that burrowing endoparasitism and sedentary endoparasitism each evolved, respectively, at least six and at least three times independently, mostly from migratory ectoparasitic ancestors. Only root-knot nematodes have evolved from burrowing endoparasitic nematodes. Traditional classifications are partially misled by this convergent evolution of feeding type and associated morphology. Contrastingly, mapping attributes of the gonoduct cellular architecture, including newly obtained data of 18 species belonging to the Aphelenchoidea, Criconematoidea, Anguinidae and Panagrolaimidae, revealed a broad congruence of the gonoduct characters and the molecular phylogenetic hypothesis. Yet, the presence of an offset spermatheca and proliferation of uterus cells has evolved multiple times, the latter associated with derived endoparasitic feeding specialization and resulting reproduction mode. Ancestral state reconstruction further revealed that the gonoduct of the morphologically and ecologically dissimilar tylenchid and cephalobid nematodes evolved from a common ancestor. 相似文献
110.
SUMMARY The genetic accommodation of novel adaptive traits may be accompanied by the evolution of correlated traits that constrain adaptive evolution. Very little is known about the removal of maladaptive correlated traits. In the present study, body size was found to have evolved as a correlated trait during the artificial selection for a polyphenism and a monophenism, and the developmental basis underlying this correlated trait was investigated. The body size and coloration were found to be developmentally integrated by titers of the insect developmental hormone, juvenile hormone (JH). Attempts to uncouple the two traits resulted in the evolution of one of the body size determinants—the critical weight—but not the delay period whose evolution is constrained by JH titers. Thus, maladaptive correlated traits can be removed when multiple developmental modules exist, and the evolution of one or more of these modules is not constrained. 相似文献