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1.
Levans produced by four Zymomonas mobilis strains showed antitumour activity against sarcoma 180 and Ehrlich carcinoma in Swiss albino mice. Levans from two strains (ZAP and CP4) had the highest effects. NMR analysis showed that the polymers were composed only of fructose units. The results suggested that the antineoplasic effect is associated to the polysaccharide molecular weight and that a particular molecular weight range may be responsible for this effect. 相似文献
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Swimming performance of silver eels is severely impaired by the swim-bladder parasite Anguillicola crassus 总被引:1,自引:0,他引:1
A.P. Palstra D.F.M. Heppener C. Székely 《Journal of experimental marine biology and ecology》2007,352(1):244-256
Infection with the swim-bladder parasite Anguillicola crassus is suggested as one of the principal causes of the collapse of the European eel population. This nematode has been introduced in Europe from Asia in the 80s and parasitized in a short time Anguilla eel species in different geographical regions across the globe. The parasites drain energy due to their sanguivorous feeding and they cause mechanical damage on the swim-bladder wall. These two effects are hypothesized to impair the spawning migration of the European eel. In this study, we have investigated both effects on swimming performance. We hypothesized that parasitic sanguivorous activities - related to parasite weight - reduce swimming endurance, while mechanical damage of the swim-bladder impairs buoyancy control. Eighty eels suffering various degrees of infection were introduced in swim-tunnels and subjected to a swimming fitness test. The relation between A. crassus infection and swimming efficiency was measured for large female silver eels swimming at various speeds. Infected eels had lower cruising speeds and a higher cost of transport. Eels without parasites, but with a damaged swim-bladder showed similar effects. Almost half of the eels that contained damaged swim-bladders (43%) stopped swimming at low aerobic swimming speeds (< 0.7 m/s). Simulated migration trials in a recent related study have confirmed that eels with a high parasite level or with damaged swim-bladder show early migration failure (< 1000-km). Reduced swimming performance appears to be associated with swim-bladder dysfunction. As we found that especially silver eels have much higher infection levels than yellow eels, it is concluded that migrating silver eels with severely infected or damaged swim-bladders are unable to reach the spawning grounds. 相似文献
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Paulo FP Pimenta Alessandra S Orfano Ana C Bahia Ana PM Duarte Claudia M Ríos-Velásquez Fabrício F Melo Felipe AC Pessoa Giselle A Oliveira Keillen MM Campos Luis Martínez Villegas Nilton Barnabé Rodrigues Rafael Nacif-Pimenta Rejane C Sim?es Wuelton M Monteiro Rogerio Amino Yara M Traub-Cseko José BP Lima Maria GV Barbosa Marcus VG Lacerda Wanderli P Tadei Nágila FC Secundino 《Memórias do Instituto Oswaldo Cruz》2015,110(1):23-47
In the Americas, areas with a high risk of malaria transmission are mainly located in
the Amazon Forest, which extends across nine countries. One keystone step to
understanding the Plasmodium life cycle in Anopheles species from the Amazon Region
is to obtain experimentally infected mosquito vectors. Several attempts to colonise
Ano- pheles species have been conducted, but with only short-lived success or no
success at all. In this review, we review the literature on malaria transmission from
the perspective of its Amazon vectors. Currently, it is possible to develop
experimental Plasmodium vivax infection of the colonised and field-captured vectors
in laboratories located close to Amazonian endemic areas. We are also reviewing
studies related to the immune response to P. vivax infection of Anopheles aquasalis,
a coastal mosquito species. Finally, we discuss the importance of the modulation of
Plasmodium infection by the vector microbiota and also consider the anopheline
genomes. The establishment of experimental mosquito infections with Plasmodium
falciparum, Plasmodium yoelii and Plasmodium berghei parasites that could provide
interesting models for studying malaria in the Amazonian scenario is important.
Understanding the molecular mechanisms involved in the development of the parasites
in New World vectors is crucial in order to better determine the interaction process
and vectorial competence. 相似文献
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Adam Southon Nickless Palstra Nicholas Veldhuis Ann Gaeth Charles Robin Richard Burke James Camakaris 《Biometals》2010,23(4):681-694
Copper-transporting P(IB)-type ATPases are highly conserved, and while unicellular eukaryotes and invertebrates have only
one, a gene duplication has occurred during vertebrate evolution. Copper-induced trafficking of mammalian ATP7A and ATP7B
from the trans-Golgi Network towards the plasma membrane is critical for their role in copper homeostasis. In polarized epithelial
cells ATP7A and ATP7B traffic towards the basolateral and apical membranes respectively. We examined the localization and
function of DmATP7, the single Drosophila
melanogaster orthologue, in cultured D.
melanogaster and mammalian cells to explore the conservation of P(IB)-type ATPase function. Comparative genomic analysis demonstrated
motifs involved in basolateral targeting and retention of ATP7A were conserved in DmATP7, whereas ATP7B targeting motifs were
not. DmATP7 expression was able to correct the copper hyper-accumulation phenotype of cultured fibroblasts from a Menkes disease
patient expressing a null ATP7A allele. DmATP7 was able to transport copper to the cupro-enzyme tyrosinase and under elevated copper conditions DmATP7 was
able to traffic towards the plasma membrane and efflux copper, essentially phenocopying ATP7A. When expressed in polarized
Madin-Darby Canine Kidney cells, DmATP7 translocated towards the basolateral membrane when exposed to elevated copper, similar
to ATP7A. These results demonstrate DmATP7 is able to functionally compensate for the absence of ATP7A, with important trafficking
motifs conserved in these distantly related orthologues. 相似文献
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Sune Skeldal Alex M. Sykes Simon Glerup Dusan Matusica Nickless Palstra Henri Autio Zoran Boskovic Peder Madsen Eero Castrén Anders Nykjaer Elizabeth J. Coulson 《The Journal of biological chemistry》2012,287(52):43798-43809
Neurotrophins comprise a group of neuronal growth factors that are essential for the development and maintenance of the nervous system. However, the immature pro-neurotrophins promote apoptosis by engaging in a complex with sortilin and the p75 neurotrophin receptor (p75NTR). To identify the interaction site between sortilin and p75NTR, we analyzed binding between chimeric receptor constructs and truncated p75NTR variants by co-immunoprecipitation experiments, surface plasmon resonance analysis, and FRET. We found that complex formation between sortilin and p75NTR relies on contact points in the extracellular domains of the receptors. We also determined that the interaction critically depends on an extracellular juxtamembrane 23-amino acid sequence of p75NTR. Functional studies further revealed an important regulatory function of the sortilin intracellular domain in p75NTR-regulated intramembrane proteolysis and apoptosis. Thus, although the intracellular domain of sortilin does not contribute to p75NTR binding, it does regulate the rates of p75NTR cleavage, which is required to mediate pro-neurotrophin-stimulated cell death. 相似文献
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With an ecological-evolutionary perspective increasingly applied toward the conservation and management of endangered or exploited species, the genetic estimation of effective population size (Ne) has proliferated. Based on a comprehensive analysis of empirical literature from the past two decades, we asked: (i) how often do studies link Ne to the adult census population size (N)? (ii) To what extent is Ne correctly linked to N? (iii) How readily is uncertainty accounted for in both Ne and N when quantifying Ne/N ratios? and (iv) how frequently and to what degree might errors in the estimation of Ne or N affect inferences of Ne/N ratios? We found that only 20% of available Ne estimates (508 of 2617; 233 studies) explicitly attempted to link Ne and N; of these, only 31% (160 of 508) correctly linked Ne and N. Moreover, only 7% (41 of 508) of Ne/N ratios (correctly linked or not) reported confidence intervals for both Ne and N; for those cases where confidence intervals were reported for Ne only, 31% of Ne/N ratios overlapped with 1, of which more than half also reached below Ne/N = 0.01. Uncertainty in Ne/N ratios thus sometimes spanned at least two orders of magnitude. We conclude that the estimation of Ne/N ratios in natural populations could be significantly improved, discuss several options for doing so, and briefly outline some future research directions. 相似文献
9.
Marco Graziano Raul Benito Josep V. Planas Arjan P. Palstra 《BMC developmental biology》2018,18(1):10
Background
Male European seabass, already predominant (~?70%) in cultured stocks, show a high incidence (20–30%) of precocious sexual maturation under current aquaculture practices, leading to important economic losses for the industry. In view of the known modulation of reproductive development by swimming exercise in other teleost species, we aimed at investigating the effects of sustained swimming on reproductive development in seabass males during the first year of life in order to determine if swimming could potentially reduce precocious sexual maturation.Methods
Pre-pubertal seabass (3.91?±?0.22 g of body weight (BW)) were subjected to a 10 week swimming regime at their optimal swimming speed (Uopt) in an oval-shaped Brett-type flume or kept at rest during this period. Using Blazka-type swim tunnels, Uopt was determined three times during the course of the experiment: 0.66 m s??1 at 19?±?1 g BW, 10.2?±?0.2 cm of standard length (SL) (week 1); 0.69 m s??1 at 38?±?3 g BW, 12.7?±?0.3 cm SL (week 5), and also 0.69 m s??1 at 77?±?7 g BW, 15.7?±?0.5 cm SL (week 9). Every 2 weeks, size and gonadal weight were monitored in the exercised (N?=?15) and non-exercised fish (N?=?15). After 10 weeks, exercised and non-exercised males were sampled to determine plasma 11-ketotestosterone levels, testicular mRNA expression levels of genes involved in steroidogenesis and gametogenesis by qPCR, as well as the relative abundance of germ cells representing the different spermatogenic stages by histological examination.Results
Our results indicate that sustained swimming exercise at Uopt delays testicular development in male European seabass as evidenced by decreased gonado-somatic index, slower progression of testicular development and by reduced mRNA expression levels of follicle stimulating hormone receptor (fshR), 3-beta-hydroxysteroid dehydrogenase (3βhsd), 11-beta hydroxysteroid dehydrogenase (11βhsd), estrogen receptor-beta (erβ2), anti-mullerian hormone (amh), structural maintenance of chromosomes protein 1B (smc1β), inhibin beta A (inhba) and gonado-somal derived factor 1 (gsdf1) in exercised males as compared with the non-exercised males.Conclusions
Swimming exercise may represent a natural and non-invasive tool to reduce the incidence of sexually precocious males in seabass aquaculture.10.
Palstra AP Tudorache C Rovira M Brittijn SA Burgerhout E van den Thillart GE Spaink HP Planas JV 《PloS one》2010,5(12):e14483