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41.
N Lübcker J Dabrowski TA Zengeya PJ Oberholster G Hall S Woodborne 《African Journal of Aquatic Science》2016,41(4):399-411
The alien invasive silver carp Hypophthalmichthys molitrix established a self-sustaining feral population in an oligotrophic impoundment, Flag Boshielo Dam, in South Africa. The ability of this population to persist in a dam with low algal biomass (median annual suspended chlorophyll a = 0.08 µg l?1), and limited access to rivers considered large enough for successful spawning, has implications for their invasive potential in other systems. Stomach content and stable isotope analysis were used to assess the trophic ecology of H. molitrix, which was then compared with indigenous Mozambique tilapia Oreochromis mossambicus, on a seasonal basis during 2011. Hypophthalmichthys molitrix are generalist filter feeders, with a diet consisting primarily of sediment, vegetative detritus, dinoflagellates and diatoms. The dominance of sediments in their stomachs suggests occasional benthic scavenging. However, H. molitrix occupied a higher trophic level (TL = 2.8) than expected, suggesting that this population subsidised their diet with an unidentified dietary constituent, characterised by enriched nitrogen values. Although the stomach contents indicated dietary overlap between H. molitrix and O. mossambicus, stable isotopes revealed fine-scale resource partitioning, despite both species occupying the same trophic level. Nonetheless, the persistence of this feral H. molitrix population in an oligotrophic impoundment highlights their phenotypic plasticity. 相似文献
42.
PJ Gokhale 《Biotechnic & histochemistry》2016,91(8):540-548
The extraction of statistically meaningful quantitative information from microscopy images is increasingly important for modern biological research. Obtaining accurate, quantitative information from biological specimens, however, is a complex process that requires optimization of several parameters. One must consider the number of probes, fluorescent channels required, type of plate to be used, number of fields to be acquired and optimal resolution for image acquisition. The extraction of information from images is dependent on and can be aided greatly by careful consideration of the factors involved in the image acquisition process. I summarize here the general principles behind the imaging and software technology that is used to quantify images and highlight particular issues of concern for critically applying image quantitation techniques for research. 相似文献
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Surveys were distributed to New Zealand land users in 1998 and 2008 to acquire information about New Zealand frogs with the aim of compiling and mapping their distribution and inferred population trends without costly and time-consuming field surveys. The overall frog population trend was reported as declining, with possible causes reported as an increase in agriculture, an increase in the distribution of predatory fish and disease. The resultant maps could be used for four main purposes: 1) to identify regions where Litoria populations are known to occur, which can be eliminated when considering suitable regions for translocation of Leiopelma; 2) to identify growing or stable populations of Litoria species, which may assist future disease surveys, population monitoring and to identify sources of genetic material that may serve as an Ark for declining Australian populations; 3) to highlight populations that are in decline to enable effective targeting of detailed disease studies; and 4) to approximate the stability of amphibian populations in the absence of more accurate, but costly, scientific monitoring. 相似文献
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Emma L Hesketh John RP Knight Rosemary HC Wilson James PJ Chong Dawn Coverley 《Cell cycle (Georgetown, Tex.)》2015,14(3):333-341
The minichromosome maintenance complex (MCM2-7) is the putative DNA helicase in
eukaryotes, and essential for DNA replication. By applying serial extractions to mammalian
cells synchronized by release from quiescence, we reveal dynamic changes to the
sub-nuclear compartmentalization of MCM2 as cells pass through late G1 and early S phase,
identifying a brief window when MCM2 becomes transiently attached to the nuclear-matrix.
The data distinguish 3 states that correspond to loose association with chromatin prior to
DNA replication, transient highly stable binding to the nuclear-matrix coincident with
initiation, and a post-initiation phase when MCM2 remains tightly associated with
chromatin but not the nuclear-matrix. The data suggests that functional MCM complex
loading takes place at the nuclear-matrix. 相似文献
47.
Andreas Skouras Katja Broeg Halim Dizer Hein von Westernhagen Peter-Diedrich Hansen Dieter Steinhagen 《Helgoland Marine Research》2003,57(3-4):190-198
Immunological biomarkers that reflect the effects of exposure to environmental contaminants in coastal marine habitats were
sought in European flounder (Platichthys flesus) from five locations in the German Bight with different anthropogenic impacts. During a 2-year period of sampling, innate
immune responses were monitored from a total of 331 individual flounder of a body length of 18 to 25 cm. From the fish, plasma
lysozyme, phagocytosis and respiratory burst activity of head kidney leucocytes were analysed and implemented as part of an
integrated biological effects monitoring programme. As the measurements of the parameters applied here varied within wide
ranges at some locations, spatial differences could not always be established, but some general trends could be drawn: plasma
lysozyme activity was decreased in flounder contaminated with DDT adducts and some PCBs, while cellular functions such as
phagocytosis and respiratory burst were stimulated by some chlorinated hydrocarbons. Correlation analysis also revealed connections
not only between the parameters applied here and some contaminants but also with some biochemical parameters used as biomarkers
in pollution monitoring: in flounder with decreased integrity of hepatocyte lysosomal membranes, immune functions also were
impaired, and plasma lysozyme as well as phagocytosis activity of head kidney cells were impaired when the activity of cytochrome
P450 1A was induced. The data presented here indicate that innate immune responses may be useful parameters to monitor cellular
functions in a battery of biomarkers of different levels of biological organisation.
Communicated by H. v. Westernhagen, A. Diamant 相似文献
48.
Apoptosis is characterized by DNA strand breaks with a 3'-OH terminus, which are analyzed by terminal deoxy(d)-UTP nick end labeling (TUNEL). Proteinase K digestion is thought to be an essential step in the TUNEL procedure. The effects of decalcifying reagents on general staining and the TUNEL assay for cartilage sections are largely unknown. The effects of these reagents on retention and integrity of DNA in chondrocytes have not been described until now. We evaluated the effects of various decalcifying solutions, including 10% EDTA, 10% citric acid, 5% trichloroacetic acid, 5% acetic acid and a commercial hydrochloric acid-based reagent, on general cartilage staining and the TUNEL assay for cartilage. The effects of proteinase K on nucleus preservation were also examined. Decalcification with 10% EDTA gave the best result for general cartilage staining. Chondrocyte DNA was retained and intact after using this reagent. Decalcification with 10% EDTA is also the safest method of decalcification if the TUNEL assay is applied to cartilage. Proteinase K digestion may have adverse effects on nucleus preservation in cartilage. Awareness of these effects is important whenever the TUNEL assay is applied. 相似文献
49.
MG Mullender NA Blom M De Kleuver JM Fock WMGC Hitters AMC Horemans CJ Kalkman JEH Pruijs RR Timmer PJ Titarsolej NC Van Haasteren Tol-de MJ Van Jager AJ Van Vught BJ Van Royen 《Scoliosis》2008,3(1):1-14
Background
Children with neuromuscular disorders with a progressive muscle weakness such as Duchenne Muscular Dystrophy and Spinal Muscular Atrophy frequently develop a progressive scoliosis. A severe scoliosis compromises respiratory function and makes sitting more difficult. Spinal surgery is considered the primary treatment option for correcting severe scoliosis in neuromuscular disorders. Surgery in this population requires a multidisciplinary approach, careful planning, dedicated surgical procedures, and specialized after care.Methods
The guideline is based on scientific evidence and expert opinions. A multidisciplinary working group representing experts from all relevant specialties performed the research. A literature search was conducted to collect scientific evidence in answer to specific questions posed by the working group. Literature was classified according to the level of evidence.Results
For most aspects of the treatment scientific evidence is scarce and only low level cohort studies were found. Nevertheless, a high degree of consensus was reached about the management of patients with scoliosis in neuromuscular disorders. This was translated into a set of recommendations, which are now officially accepted as a general guideline in the Netherlands.Conclusion
In order to optimize the treatment for scoliosis in neuromuscular disorders a Dutch guideline has been composed. This evidence-based, multidisciplinary guideline addresses conservative treatment, the preoperative, perioperative, and postoperative care of scoliosis in neuromuscular disorders. 相似文献50.
PJ?Baker H?Johnston M?Abel HM?Charlton PJ?O'ShaughnessyEmail author 《Reproductive biology and endocrinology : RB&E》2003,1(1):4
During mammalian testis development distinct generations of fetal and adult Leydig cells arise. Luteinising hormone (LH) is
required for normal adult Leydig cell function and for the establishment of normal adult Leydig cell number but its role in
the process of adult Leydig cell differentiation has remained uncertain. In this study we have examined adult Leydig cell
differentiation in gonadotrophin-releasing hormone (GnRH)-null mice which are deficient in circulating gonadotrophins. Adult
Leydig cell differentiation was assessed by measuring expression of mRNA species encoding four specific markers of adult Leydig
cell differentiation in the mouse. Each of these markers (3β-hydroxysteroid dehydrogenase type VI (3βHSD VI), 17β-hydroxysteroid
dehydrogenase type III (17βHSD III), prostaglandin D (PGD)-synthetase and oestrogen sulphotransferase (EST)) is expressed
only in the adult Leydig cell lineage in the normal adult animal. Real-time PCR studies showed that all four markers are expressed
in adult GnRH-null mice. Localisation of 3βHSD VI and PGD-synthetase expression by in situ hybridisation confirmed that these genes are expressed in the interstitial tissue of the GnRH-null mouse. Treatment of animals
with human chorionic gonadotrophin increased expression of 3βHSD VI and 17βHSD III within 12 hours further indicating that
differentiated, but unstimulated cells already exist in the GnRH-null mouse. Thus, while previous studies have shown that
LH is required for adult Leydig cell proliferation and activity, results from the present study show that adult Leydig cell
differentiation will take place in animals deficient in LH. 相似文献