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11.
12.
Species loss is a global issue. With up to a million species at risk and insufficient protected area to maintain the world's biodiversity, humanity will increasingly need to rely on species re‐introductions to locally restore diversity and function. However, such restoration attempts are bound to fail when ecological communities get locked in a closed state that is resistant to recovery. It is presently unknown how to repair these closed systems. We use mathematical models to identify ways out of this problem. We first show how ecological communities may enter a closed state, to then explain how to open them up again for restoration of their original diversity. We find that restoration is often still possible shortly after initial species loss, as (1) the secondary extinctions that produce closure have not happened yet and (2) mild population fluctuations still allow successful repair during a transient postdisturbance phase. However, after this typically short window of opportunity for restoration, the system enters a new equilibrium, which may be a closed state. Our analysis shows how to take ecological communities out of the closed state: Appropriate management of carrying capacities produces a regime of mild population fluctuations that opens a window for successful species re‐introductions. These windows can be perpetually recurring or permanently open. Such opportunities for repair can be absent under regimes of wild cycles or perfect stability. We conclude that mild cycles may open windows of opportunity for the repair of communities that have become resistant to recovery. 相似文献
13.
Pushpa M. Jairam Pim A. de Jong Willem P. T?h. M. Mali Ivana Isgum Harry J. de Koning Carlijn van der Aalst Matthijs Oudkerk Rozemarijn Vliegenthart Yolanda van der Graaf 《PloS one》2013,8(6)
Background
Current smokers have an increased cardiovascular disease (CVD) risk compared to ex-smokers due to reversible as well as irreversible effects of smoking. We investigated if current smokers remain to have an increased CVD risk compared to ex-smokers in subjects with a long and intense smoking history. We in addition studied if the effect of smoking continuation on CVD risk is independent of or modified by the presence of cardiovascular calcifications.Methods
The cohort used comprised a sample of 3559 male lung cancer screening trial participants. We conducted a case-cohort study using all CVD cases and a random sample of 10% (n = 341) from the baseline cohort (subcohort). A weighted Cox proportional hazards model was used to estimate the hazard ratios for current smoking status in relation to CVD events.Results
During a median follow-up of 2.6 years (max. 3.7 years), 263 fatal and non-fatal cardiovascular events (cases) were identified. Age, packyears and cardiovascular calcification adjusted hazard ratio of current smokers compared to former smokers was 1.33 (95% confidence interval 1.00–1.77). In additional analyses that incorporated multiplicative interaction terms, neither coronary nor aortic calcifications modified the association between smoking status and cardiovascular risk (P = 0.08).Conclusions
Current smokers have an increased CVD risk compared to former smokers even in subjects with a long and intense smoking history. Smoking exerts its hazardous effects on CVD risk by pathways partly independent of cardiovascular calcifications. 相似文献14.
Approaches to homozygosity mapping and exome sequencing for the identification of novel types of CDG
Gert Matthijs Daisy Rymen María Beatriz Bistué Millón Erika Souche Valérie Race 《Glycoconjugate journal》2013,30(1):67-76
In the past decade, the identification of most genes involved in Congenital Disorders of Glycosylation (CDG) (type I) was achieved by a combination of biochemical, cell biological and glycobiological investigations. This has been truly successful for CDG-I, because the candidate genes could be selected on the basis of the homology of the synthetic pathway of the dolichol linked oligosaccharide in human and yeast. On the contrary, only a few CDG-II defects were elucidated, be it that some of the discoveries represent wonderful breakthroughs, like e.g, the identification of the COG defects. In general, many rare genetic defects have been identified by positional cloning. However, only a few types of CDG have effectively been elucidated by linkage analysis and so-called reverse genetics. The reason is that the families were relatively small and could—except for CDG-PMM2—not be pooled for analysis. Hence, a large number of CDG cases has long remained unsolved because the search for the culprit gene was very laborious, due to the heterogeneous phenotype and the myriad of candidate defects. This has changed when homozygosity mapping came of age, because it could be applied to small (consanguineous) families. Many novel CDG genes have been discovered in this way. But the best has yet to come: what we are currently witnessing, is an explosion of novel CDG defects, thanks to exome sequencing: seven novel types were published over a period of only two years. It is expected that exome sequencing will soon become a diagnostic tool, that will continuously uncover new facets of this fascinating group of diseases. 相似文献
15.
Leif Sönnichsen Matthijs Bokje Jessica Marchal Heribert Hofer Bogumiła Jędrzejewska Stephanie Kramer‐Schadt Sylvia Ortmann 《Ethology : formerly Zeitschrift fur Tierpsychologie》2013,119(3):233-243
In natural environments, predation risk varies over time. The risk allocation hypothesis predicts that prey is expected to adjust key anti‐predator behaviours such as vigilance to temporal variation in risk. We tested the predictions of the risk allocation hypothesis in a natural environment where both a species‐rich natural predator community and human hunters are abundant and where the differences in seasonal and circadian activity between natural and anthropogenic predators provided a unique opportunity to quantify the contributions of different predator classes to anti‐predator behaviour. Whereas natural predators were expected to show similar levels of activity throughout the seasons, hunter activity was high during the daytime during a clearly defined hunting season. According to the risk allocation hypothesis, vigilance should then be higher during the hunting season and during daytime hours than during the non‐hunting season and night‐time hours. Roe deer (Capreolus capreolus) on the edge of Bia?owie?a Primeval Forest in Eastern Poland displayed vigilance behaviour consistent with these predictions. The behavioural response of roe deer to temporarily varying predation risks emphasises the behavioural plasticity of this species and suggests that future studies of anti‐predator behaviour need to incorporate circadian variation in predation pressure as well as risk gradients of both natural and anthropogenic predators. 相似文献
16.
Lumeng Ye Steven Ballet Falk Hildebrand Georges Laus Karel Guillemyn Jeroen Raes Sandra Matthijs José Martins Pierre Cornelis 《Biometals》2013,26(4):561-575
The structure of a pyoverdine produced by Pseudomonas putida, W15Oct28, was elucidated by combining mass spectrometric methods and bioinformatics by the analysis of non-ribosomal peptide synthetase genes present in the newly sequenced genome. The only form of pyoverdine produced by P. putida W15Oct28 is characterized to contain α-ketoglutaric acid as acyl side chain, a dihydropyoverdine chromophore, and a 12 amino acid peptide chain. The peptide chain is unique among all pyoverdines produced by Pseudomonas subspecies strains. It was characterized as –l-Asp-l-Ala-d-AOHOrn-l-Thr-Gly-c[l-Thr(O-)-l-Hse-d-Hya-l-Ser-l-Orn-l-Hse-l-Ser-O-]. The chemical formula and the detected and calculated molecular weight of this pyoverdine are: C65H93N17O32, detected mass 1624.6404 Da, calculated mass 1624.6245. Additionally, pyoverdine structures from both literature reports and bioinformatics prediction of the genome sequenced P. putida strains are summarized allowing us to propose a scheme based on pyoverdines structures as tool for the phylogeny of P. putida. This study shows the strength of the combination of in silico analysis together with analytical data and literature mining in determining the structure of secondary metabolites such as peptidic siderophores. 相似文献
17.
E. Remmelink A. Aartsma‐Rus A. B. Smit M. Verhage M. Loos M. van Putten 《Genes, Brain & Behavior》2016,15(6):558-567
Duchenne muscular dystrophy (DMD) is a progressive muscle‐wasting disorder, caused by mutations in the DMD gene and the resulting lack of dystrophin. The DMD gene has seven promoters, giving rise to multiple full‐length and shorter isoforms. Besides the expression of dystrophin in muscles, the majority of dystrophin isoforms is expressed in brain and dystrophinopathy can lead to cognitive deficits, including intellectual impairments and deficits in executive function. In contrast to the muscle pathology, the impact of the lack of dystrophin on the brain is not very well studied. Here, we study the behavioral consequences of a lack of full‐length dystrophin isoforms in mdx mice, particularly with regard to domains of executive functions and anxiety. We observed a deficit in cognitive flexibility in mdx mice in the absence of motor dysfunction or general learning impairments using two independent behavioral tests. In addition, increased anxiety was observed, but its expression depended on the context. Overall, these results suggest that the absence of full‐length dystrophin in mice has specific behavioral effects that compare well to deficits observed in DMD patients. 相似文献
18.
High residual activity of PMM2 in patients' fibroblasts: possible pitfall in the diagnosis of CDG-Ia (phosphomannomutase deficiency)
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Grünewald S Schollen E Van Schaftingen E Jaeken J Matthijs G 《American journal of human genetics》2001,68(2):347-354
Congenital disorders of glycosylation (CDGs) are a rapidly enlarging group of inherited diseases with abnormal N-glycosylation of glycoconjugates. Most patients have CDG-Ia, which is due to a phosphomannomutase (PMM) deficiency. In this article, we report that a significant portion (9 of 54) of patients with CDG-Ia had a rather high residual PMM activity in fibroblasts included in the normal range (means of the controls +/- 2 SD) and amounting to 35%-70% of the mean control value. The clinical diagnosis of CDG-Ia was made difficult by the fact that most (6 of 9) of these patients belong to a subgroup characterized by a phenotype that is milder than classical CDG-Ia. These patients lack some of the symptoms that are suggestive for the diagnosis, such as inverted nipples and abnormal fat deposition, and, as a mean, had higher residual PMM activities in fibroblasts (2.05+/-0.61 mU/mg protein, n=9; vs. controls 5.34+/-1.74 mU/mg protein, n=22), compared with patients with moderate (1.32+/-0.86 mU/mg protein, n=18) or severe (0.63+/-0.56 mU/mg protein, n=27, P<.001) cases. Yet they all showed mild mental retardation, hypotonia, cerebellar hypoplasia, and strabismus. All of them had an abnormal serum transferrin pattern and a significantly reduced PMM activity in leukocytes. Six of the nine patients with mild presentations were compound heterozygotes for the C241S mutation, which is known to reduce PMM activity by only approximately 2-fold. Our results indicate that intermediate PMM values in fibroblasts may mask the diagnosis of CDG-Ia, which is better accomplished by measurement of PMM activity in leukocytes and mutation search in the PMM2 gene. They also indicate that there is some degree of correlation between the residual activity in fibroblasts and the clinical phenotype. 相似文献
19.
Delineation of the critical deletion region for congenital heart defects, on chromosome 8p23.1
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Devriendt K Matthijs G Van Dael R Gewillig M Eyskens B Hjalgrim H Dolmer B McGaughran J Bröndum-Nielsen K Marynen P Fryns JP Vermeesch JR 《American journal of human genetics》1999,64(4):1119-1126
Deletions in the distal region of chromosome 8p (del8p) are associated with congenital heart malformations. Other major manifestations include microcephaly, intrauterine growth retardation, mental retardation, and a characteristic hyperactive, impulsive behavior. We studied genotype-phenotype correlations in nine unrelated patients with a de novo del8p, by using the combination of classic cytogenetics, FISH, and the analysis of polymorphic DNA markers. With the exception of one large terminal deletion, all deletions were interstitial. In five patients, a commonly deleted region of approximately 6 Mb was present, with breakpoints clustering in the same regions. One patient without a heart defect or microcephaly but with mild mental retardation and characteristic behavior had a smaller deletion within this commonly deleted region. Two patients without a heart defect had a more proximal interstitial deletion that did not overlap with the commonly deleted region. Taken together, these data allowed us to define the critical deletion regions for the major features of a del8p. 相似文献
20.
Apolipoprotein B (apoB) is the sole protein component of low-density lipoprotein (LDL) and is thought to play an important role in atherogenesis. We performed a meta-analysis of the associations between the three most frequently investigated polymorphisms (XbaI, signal peptide insertion/deletion, EcoRI) in the apolipoprotein B (APOB) gene, lipid parameters, and the risk of ischemic heart disease (IHD). We restricted our analysis to Caucasians. Homozygotes for the XbaI X+ allele had significantly elevated levels of LDL cholesterol (LDL-C) and apoB, but a decreased risk (OR=0.80; 95%CI: 0.66–0.96) of IHD. Homozygosity for the signal peptide deletion allele was associated with similarly increased levels of LDL-C and apoB, and with an increased risk of IHD (OR=1.30; 95%CI: 1.08–1.58). Subjects homozygous for the rare EcoRI allele had significantly decreased levels of total and LDL cholesterol, but unaltered risk of IHD. We conclude that all three polymorphic apoB sites are associated with altered lipid levels, but not necessarily with a consistently altered risk of IHD. These data suggest that the relationship between apoB levels, hypercholesterolemia and IHD risk cannot have a simple molecular basis in the apoB gene. 相似文献