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1.
Mitochondria are well-characterized intracellular organelles usually concentrated in locations of high energy consumption. Light microscopic and transmission electron microscopic observations of the internal anatomy of the feather mites Diplaegidia columbae and Falculifer rostratus were conducted. In the anterior half of the bodies of the mites, we found several dozen of distinctive mitochondria-rich (MR) cells filled with abundant, large mitochondria. Mitochondria are placed individually or enclosed in small groups within an elaborated lamellar system forming a mitochondria–lamellae complex (MLC). The role of the MLC as well as the MR cells is not clear at present, but their involvement in heat generation is hypothesized and briefly discussed.  相似文献   

2.
The ammonium analogue, methylamine, is taken up rapidly from dilute solution by Macrocystis pyrifera (L.) C. A. Agardh. 14C-methylamine was used to characterize the transport system, with respect to dependence on external concentration, temperature, pH and substrate specificity. The results suggest that methylamine enters the algal tissue via a specific mediated transport system. Uptake of methylamine showed no consistent relation to the N content of the plant tissue, but was highly dependent on the portion of plant sampled and severely affected by cutting the tissue. The strong inhibition of methylamine uptake by ammonium and lesser inhibition by other alkylamines suggests that the uptake system functions as an “ammonium permease”. Uptake of 14C-methylamine can be used as a highly sensitive measure of NH4+ uptake activity and should be a useful tool for studying NH4+ uptake in the laboratory and field.  相似文献   

3.
The photo-Fenton coupled with a biological system for the removal of di-(2-ethylhexyl) phthalate (DEHP) in wastewater was analyzed. The toxicity of DEHP-containing wastewater was found to be reduced after pretreatment by the photo-Fenton reaction. The effect of different factors, such as DEHP, Fe3+ and H2O2 concentrations and the reaction time, on degradation efficiency was investigated. The optimal time to stop the pretreatment process and introduce the effluent to the biological system was 60 min. The results show that effluent of DEHP-containing wastewater pretreated by the photo-Fenton method is biodegradable and that mineralization can be completed when the wastewater is subsequently treated in a biological system. The coupled Fenton and biological treatment system for the degradation of DEHP-containing wastewater can be successfully performed in a semi-continuous mode. These results indicate that the coupled photo-biological system is an effective and potential method for the treatment of DEHP-containing wastewater.  相似文献   

4.
5.
Photosynthetic characteristics of four high-CO2-requiring mutants of Chlamydomonas reinhardtii were compared to those of wild type before and after a 24-hour exposure to limiting CO2 concentrations. The four mutants represent two loci involved in the CO2-concentrating system of this unicellular alga. All mutants had a lower photosynthetic affinity for inorganic carbon than did the wild type when grown at an elevated CO2 concentration, indicating that the genetic lesion in each is expressed even at elevated CO2 concentrations. Wild type and all four mutants exhibited adaptive responses to limiting CO2 characteristic of the induction of the CO2-concentrating system, resulting in an increased affinity for inorganic carbon only in wild type. Although other components of the CO2-concentrating system were induced in these mutants, the defective component in each was sufficient to prevent any increase in the affinity for inorganic carbon. It was concluded that the genes corresponding to the ca-1 and pmp-1 loci exhibit at least partially constitutive expression and that all components of the CO2-concentrating system may be required to significantly affect the photosynthetic affinity for inorganic carbon.  相似文献   

6.

Objective

To describe the magnetic resonance imaging (MRI) patterns of the central nervous system (CNS) involvement by neuroparacoccidioidomycosis (NPCM).

Methods

Between January 1999 and March 2011, a review of MRI data analysis from 8 cases of NPCM was performed. The following MRI characteristics were examined by an experienced neuroradiologist: topography of lesions, aspects on T1- and T2-weighted images (WI), contrast enhancement, diffusion and spectroscopy.

Results

All patients had evidence of paracoccidioidomycosis infection outside the nervous system. Regarding CNS involvement, five patients had only supratentorial lesions; three had infra- and supratentorial ones. Meningeal extension occurred in three patients. The lesions were predominantly hyperintense on T1WI. At T2WI, a hypointense component was present in five cases as well as a perilesional abnormal white matter. A ring-enhancement pattern was seen in five cases. Spectroscopy was performed in three patients and showed an increased lipid peak in all of them. In one case, there was also an increased choline peak.

Conclusion

NPCM is rare, and MRI may help its differentiation from other inflammatory lesions. However, the presence of active infection outside CNS and some imaging characteristics should point to this diagnosis.  相似文献   

7.
Membrane adenylate cyclase (AC) from polymorphonuclear (PMN) leucocytes and platelet membranes are activated several fold by fluoride and prostaglandin E1 (PGE1) respectively. Incubation of such activated membranes in a phosphorylating system inhibits cyclase activity. The inhibition can now be relieved by further treatment with fluoride and PGE1 respectively. These findings suggest that AC exists in an inhibited phospho- and activated dephospho-form. This is supported by the finding that membrane preparations from both sources contain a cyclic adenylate (cAMP) stimulated protein kinase and points to the existence of an adequate membrane phosphorylating system.  相似文献   

8.
The structure of the polychaete muscular system is reviewed. The muscular system comprises the muscles of the body wall, the musculature of the parapodial complex and the muscle system of the dissepiments and mesenteries. Various types of organisation of the longitudinal and circular components of the muscular body wall are distinguished. In Opheliidae, Polygordiidae, Protodrilidae, Spionidae, Oweniidae, Aphroditidae, Acoetidae (=Polyodontidae), Polynoidae, Sigalonidae, Phyllodocidae, Nephtyidae, Pisionidae, and Nerillidae circular muscles are lacking. It is hypothesised that the absence of circular muscles represents the plesiomorphic state in Annelida. This view contradicts the widely accepted idea of an earthworm-like musculature of the body wall comprising an outer layer of circular and an inner layer of longitudinal fibres. A classification of the various types of parapodial muscle construction has been developed. Massive and less manoeuvrable parapodia composed of many components like those of Aphrodita are regarded to represent the plesiomorphic state in recent polychaetes. An analysis of the diversity of the muscular structure supports the hypothesis that the primary mode of life in polychaetes was epibenthic and the parapodial chaetae had a protective function.  相似文献   

9.
The complete life cycle of Amblyospora campbelli (Kellen and Wills, 1962) (Microsporida: Amblyosporidae) requires a two-host system involving the mosquito host, Culiseta incidens (Thomson), and an obligatory intermediate copepod host. The parasite has dimorphic spore development producing meiospores (haploid condition) and binucleated spores (diploid condition), either as an exclusive infection or simultaneously (within females only). This is the 1st known report of concurrent spore development within an adult mosquito host, and, therefore, shows the Amblyospora campbelli system to be uniquely different from other Amblyospora spp. cycles previously described. The significance of dimorphic spore development is discussed. In females, diplokaryotic meronts may invade oenocytes, causing a benign-type of infection. A blood-meal is required to initiate sporulation of the binucleate spore. The binucleate spore contains the sporoplasm involved in transovarial transmission. A 2nd sporulation sequence, primarily in adipose tissue, may involve both males and females. In this sequence, repeated merogonic division greatly increased the density of diplokaryotic meronts and generally involved most of the body of the host. Production of meiospores, unlike that for the binucleate spore, appeared to be spontaneous (i.e. no obligatory blood meal). Survivorship of male and female larval mosquitoes was nearly equal. Adult females spread the parasite in three ways: transovarial, transovum, and by meiospore deposition.  相似文献   

10.
Investigation of the genetic system of six species ofPlantago has revealed striking differences in their breeding and meiotic systems.Plantago patagonica is an inbreeder on account of preanthesis cleistogamy, whereasP. lanceolata is an obligate outbreeder, as it is self-incompatible.Plantago drummondii, P. lagopus, P. ovata, andP. major show mixed mating but in varying proportions. In terms of their energy budgets, outbreeding species invest more in floral advertisement and male function, while inbreeders invest more in female function. The contribution of the meiotic system to genetic variability, as revealed through recombination index, is more important in the inbreeding species.  相似文献   

11.
《FEBS letters》1985,183(2):390-394
A poly(Phe) synthesis system was optimized for the archaebacterium Halobacterium halobium. It is essential for maximal activity to isolate the ribosomes from cells in mid-log phase. The system is characterized by the presence of tRNA from brewer's yeast, 6.4 M monovalent cations, 60 mM magnesium, 2 M sulphate anions, a pH of 7.4, and an incubation temperature of 40°C; polycations such as spermidine are not required. Under these conditions one H. halobium ribosome synthesizes statistically more than 20 Phe per h, and the synthesis is not exhausted after 2 h (40 Phe/ribosome). The yield of poly (Phe) is one to two orders of magnitude larger than corresponding yields described for other archaebacterial ribosomes. The accuracy of tRNA selection was determined, and an error fraction of about 0.5% was found. More than 30% of the ribosomes participate in poly(Phe) synthesis.  相似文献   

12.
Rhodomyrtus tomentosa (Ait.) Hassk. is widely distributed in tropical Asia and is an invasive species in Florida, USA. The purpose of the present study was to investigate the reproductive ecology of the species in order to provide information that may be useful in elucidating factors contributing to its invasiveness. The research was carried out at Heshan Hilly Land Integrated Experimental Station, the Chinese Academy of Sciences, Guangdong Province, China in 2003 and 2004. Rhodomyrtus tomentosa flowers in March or April and the flowering period lasts for about 3 months. Flowers open early in the morning and last 2–3 days. The pollen remain viable for about 12  h and the stigma is only receptive on the blooming day. The breeding system is a mixed mating system (outcrossing and geitonogamy). The species is bee-pollinated with pollen as the floral reward. Almost all pollinators appeared before 12  am. Amegilla florea (Smith) Brooks and Xylocopa nasalis Westwood are the primary pollinators for the species. The results indicate that the reproductive features of R. tomentosa – with the mixed mating system and common generalist pollinators – are not limiting factors when colonization occurs in a new environment.  相似文献   

13.
Two closely related North American orchid species, Isotria verticillata and I. medeoloides, were studied with respect to breeding system biology and pollination dynamics. Marked differences in reproductive biology were revealed. The more common I. verticillata is xenogamous, being pollinated by solitary bees in the Andrenidae, Anthophoridae, and Halictidae. The inflorescence is fragrant, multicolored, and has pollination guides, thus possessing an obvious attractant system, even though it lacks nectaries. In contrast, I. medeoloides is self-pollinating, has light green flowers, and lacks pollination guides, nectaries, and odor. These two species also differ radically in population structure and reproductive efficiency.  相似文献   

14.
Goal and Scope This study attempts to estimate the environmental performance of Polyhydroxyalkanoates (PHA), from agricultural production through the PHA fermentation and recovery process – “cradle to gate”. Two types of PHA production systems are investigated: corn grain based PHA and corn grain and corn stover based PHA. Methods Corn cultivation data are taken from 14 counties in the Corn Belt states of the United States – Illinois, Indiana, Iowa, Michigan, Minnesota, Ohio, and Wisconsin. The environmental burdens associated with the corn wet milling process, in which dextrose, corn oil, corn gluten meal and corn gluten feed are produced, are allocated to dextrose and its coproducts by the system expansion approach. Greenhouse gases include carbon taken up by soil, nitrous oxide (N2O) released from soil during corn cultivation, carbon contents in biobased products as well as carbon dioxide, methane and nitrous oxide released from industrial processing. The soil carbon and nitrogen dynamics in corn cultivation are predicted by an agro–ecosystem model, the DAYCENT model. The environmental performance of the PHA production system is compared to that of a conventional polymer fulfilling an equivalent function. The environmental performance is addressed as nonrenewable energy and selected potential environmental impacts including global warming, photochemical smog, acidification, and eutrophication. The characterization factors are adapted from the TRACI model (Tools for the Reduction and Assessment of Chemical and Other Environmental Impacts) developed by the United States Environmental Protection Agency. Results and Discussion Global warming associated with corn grain based PHA is 1.6–4.1 kg-CO2 eq. kg–1. The primary contributing process to most environmental impacts except for photochemical smog and eutrophication is the PHA fermentation and recovery process. For photochemical smog and eutrophication, the primary contributing process is corn cultivation due to nitrogen related burdens from soil. The trend of PHA fermentation development shows that the PHA fermentation technology is still immature and continues to improve, thereby also decreasing the environmental impacts. PHA produced in an integrated system, in which corn stover is harvested and used as raw material for PHA along with corn grain, offers global warming credits (negative greenhouse gas emissions), ranging from –0.28 to –1.9 kg-CO2 eq. kg–1, depending on the PHA fermentation technologies employed and significantly reduces the environmental impacts compared to corn based PHA. The significant reductions from the integrated system are due to 1) less environmental impacts in corn cultivation and wet milling, and 2) exporting surplus energy from lignin–rich residues in corn stover process.Conclusions and Outlook Under the current PHA fermentation technology, corn grain based PHA does not provide an environmental advantage over polystyrene. Corn grain based PHA produced by the near future PHA fermentation technology would be more favorable than polystyrene in terms of nonrenewable energy and global warming due to improvement in the PHA fermentation and recovery process. However, corn grain based PHA produced in even the near future technology does not provide better profiles for other environmental impacts (i.e., photochemical smog, acidification and eutrophication) than polystyrene. One of the primary reasons for high impacts of PHA in photochemical smog, acidification and eutrophication is the environmental burdens associated with corn cultivation. Thus other approaches to reduce these burdens in the agricultural process (e.g., use of buffer strips, etc.) are necessary to achieve better profiles for photochemical smog, acidification and eutrophication associated with corn cultivation. PHA produced in the integrated system is more favorable than polystyrene in terms of most environmental impacts considered here except for eutrophication.  相似文献   

15.
Three space flight experiments have been conducted to test and demonstrate the use of a passively controlled, materially closed, bioregenerative life support system in space. The Autonomous Biological System (ABS) provides an experimental environment for long term growth and breeding of aquatic plants and animals. The ABS is completely materially closed, isolated from human life support systems and cabin atmosphere contaminants, and requires little need for astronaut intervention. Testing of the ABS marked several firsts: the first aquatic angiosperms to be grown in space; the first higher organisms (aquatic invertebrate animals) to complete their life cycles in space; the first completely bioregenerative life support system in space; and, among the first gravitational ecology experiments. As an introduction this paper describes the ABS, its flight performance, advantages and disadvantages.  相似文献   

16.
The structure of the [Fe(bzimpy)2](ClO4)2·xH2O system (x = 0.25) was determined by single crystal X-ray structure analysis. The Fe(II) ion is hexacoordinated by six donor nitrogen atoms. The magnetic properties of the complex were investigated by powder magnetic susceptibility measurements and ESR. The freshly prepared sample does not show any traces of iron(III) impurities but these are formed as a function of time. After 1 year the sample contains 8.2% iron(III) as shown by UV spectroscopy and indicated by geff = 4.3 and 2.0 in its ESR spectrum. This explains the recorded ξ versus T behaviour at low temperature: with increasing temperature the ξ value decreases according to the Curie-Weiss law for a S = 5/2 system having an effective g = 4.3. Above 220 K a continuous increase in the ξ value is observed and a spin crossover applies. The spin transition is not complete at room temperature. A pronounced hysteresis is observed upon heating/cooling the sample between 220 and 414 K on the basis of magnetic data and infrared spectra.  相似文献   

17.
Cytochrome P-450(cam) monooxygenase is an important bacterial redox enzyme system with potential commercial value for detoxifying trace hydrocarbon contaminants, catalyzing regiospecific hydroxylations, and amperometric biosensing. The present study was undertaken to increase productivity of this enzyme, which is induced in its host, pseudomonas putida PpG 786, by D(+)-camphor. Culture processes were studied in batch, fed-batch, and continuous modes to evaluate metabolic behavior and develop constitutive equations for specific rate of growth (mu), camphor utilization (q(p)). Fed-batch culture was characterized by an extended linear growth phase which is often encountered in hydrocarbon fermentations. Inhibition by the camphor solvent, dimethylformamide, was assessed. Production of the terminal protein of the p-450(cam) enzyme system, cytochrome m, was shown to depend on growth medium iron content in fed-batch culture and was increased by 130% over previously protocols by eliminating iron deficiency. A continuous process that enables greater production rates was developed by using oxygen enrichment while simultaneously reducing gas throughput. Camphor and oxygen requirements were determined for fedbatch and continuous growth. (c) 1993 John Wiley & Sons, Inc.  相似文献   

18.
The nucleoside analogue, 1-(2-deoxy-2-fluoro-1-d-arabinofuranosyl)-5-iodouracil (FIAU) is a substrate for thymidine kinase (TK), which is commonly expressed in bacteria. It is currently being investigated in clinical studies as an in vivo bacterial infection detection agent. In developing countries where imaging facilities are not readily available, deploying such technology can be a big hurdle. However, a portable ex vivo system might provide a good alternative. In an in vitro system, [125I]-FIAU incubated with bacteria is phosphorylated by TK, and is trapped within the bacteria, which can be detected by radioscintography. The suitability of this agent to be utilized as part of an ex vivo bacterial detection system was evaluated. In the first part of this report, the optimization of the incubation and detection condition using E. coli as a test case is described. Samples were incubated in a growth promoting medium containing the label, then after filtering and washing, the amount of radioactivity trapped on the filter was quantitated by a scintillation counter. As a proof of concept demonstration, blinded urine samples from urinary tract infection (UTI) patients and normal donors were tested in the FIAU system. Of the 13 UTI positive and 15 normal urine samples tested, there were 2 false negatives and 1 false positive, respectively. Potential explanations for the false positive and negatives as well as the commercialization possibility of this system will be discussed.  相似文献   

19.
Dirk Brandis 《Hydrobiologia》2001,452(1-3):89-100
The Himalayas are known to be a geologically young and dynamic mountain range hosting an endemic flora and fauna. To date, for freshwater crabs, one endemic subgenus within the genus Potamon, Potamon (Himalayapotamon) Pretzmann, 1966, has been described from the Himalayas. This subgenus includes two species, Potamon atkinsonianum (Wood-Mason, 1871) and Potamon emphysetum (Alcock, 1909). The taxonomic position of these two species is reconsidered. The subgenus Himalayapotamon is raised to generic level and its systematic and zoogeographic position is discussed. Based mainly on the morphology of the male copulatory system, Himalayapotamon belongs to the family Potamidae. It is more related to the Eurasian genus Potamon Savigny, and is distinct from the South-East Asian genus Potamiscus as well as from the Indian freshwater crabs of the family Gecarcinucidae. Zoogeographically Himalayapotamon appears to be an endemic genus related to Potamon, both genera presumably being isolated during the Miocene when the Gangetic waters were separated from the western Eurasian river systems. Further speciation occurred during glacial periods.  相似文献   

20.
A survey of chromosome systems in the Eriococcidae shows that many of them are intermediates between two systems occurring elsewhere in the coccids. These two systems differ in the number of paternal chromosomes which remain heterochromatic during spermatogenesis and are then discarded. In the lecanoid system, all are discarded; in the Comstockiella system only one, the DH chromosome is discarded. Evolutionary steps from the lecanoid to the Comstockiella systems had previously been postulated with the intermediates having from n-1 down to 2 chromosomes remaining heterochromatic during spermatogenesis. The transition was believed to be reversible and the systems therefore inherently unstable. Most of the armored scales with Comstockiella systems have not shown intermediacy but one case has been recently reported. The eriococcids as a family are characteristically intermediate with frequently extreme variation from cyst to cyst in number of chromosomes remaining heterochromatic. Species with an unmodified Comstockiella system may occur but are in a minority. One unanticipated system is reported for two species, the complete Comstockiella system in which all the heterochromatic chromosomes are reversed at spermatogenesis; this system is also theoretically unstable. Indirect evidence for the great antiquity of the eriococcids is presented, and the question raised as to the maintenance of instability over several epochs. Comparative cytology may provide part of the answer to this question. The most common, and probably the basic diploid chromosome number of the eriococcids is 18, with a range from 12 to 28 and about 48; decreases in number are more frequent than increases.This work was part of a research program on coccids supported by grants from the National Science Foundation currently GB 4289.  相似文献   

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