Does environmental heterogeneity affect species co‐occurrence in ecological guilds across stream macroinvertebrate metacommunities?

Null model analyses have greatly improved our understanding of species co‐occurrence. Null model analyses have shown, for example, that cold‐blooded animals show less segregated distributions than warm‐blooded animals. This topic has rarely been studied simultaneously across multiple metacommunities. We analysed data on 10 stream metacommunities (with 10 communities in each metacommunity) of a cold‐blooded animal group, benthic macroinvertebrates, and examined co‐occurrence within five ecological guilds. We found that the segregated species co‐occurrence was not the rule in stream invertebrate guilds. This was evidenced by the finding that only 10% of the 50 guild matrices we analyzed showed significant segregation and no matrices showed significant aggregation in the within‐stream analyses. However, in the across‐streams analysis, all guilds showed significant segregation. We neither found differences in the degree of segregation among the guilds, the degree of species segregation did not increase with overall environmental heterogeneity, and there were no differences in the relationships between species segregation and overall environmental heterogeneity among the guilds. Expanding the spatial extent from single stream metacommunities (i.e. within each stream) to the whole study region (i.e. across the streams) increased significantly segregation in all guilds. Because environmental heterogeneity across streams was much higher than within single streams, overall environmental heterogeneity may nevertheless have effects on species segregation. It also seems that the effects of overall heterogeneity on species segregation were masked by mass effects in the within‐stream analyses.     

Spatial genotypical diversity of <Emphasis Type="Italic">Sesleria albicans</Emphasis> (Poaceae) in a dry grassland community

Spatial genotypical diversity of Sesleria albicans Kit. ex Schultes was studied in a dry grassland community by isozyme analysis. The aim was to identify the genetical individuals within the studied population and to assess the species’ clonal growth parameters. Vegetative mobility and branching intensity were measured in field for the sake of the correct interpretation of the results. Five isozyme systems were analyzed and interpreted (MDH, MNR, 6-PGDH, SkDH, LAP). Altogether, 98 distinct isozyme profiles were identified within an area of 2 m². Average genotype identity rapidly decreased with distance. Several very remote ramets (more than 1 m) belonging to the same genet were identified. The longest distance between ramets of the same genotype was 153 cm. With average annual rhizome increment of 13.59 mm assessed for the studied population the age of genet with the most remote ramets exceeded 56 years by a bi-directional growth and 112 years by a growth in single direction. Number of daughter tillers produced by a tiller per year was 0.67 (branching intensity, median) and the median of tiller life span was 2.5 years. The high genotypical diversity of S. albicans in the studied population could be a result of both, regular and continuous seed production with subsequent seedling recruitment and long life span of genets.     

Impaired myocardial deformation and ventricular vascular coupling in obese adolescents with dysglycemia

Patients with Diabetes mellitus (DM) are susceptible to coronary artery disease (CAD). However, the impact of DM on plaque progression in the non-stented segments of stent-implanted patients has been rarely reported. This study aimed to evaluate the impact of DM on the prevalence, characteristics and severity of coronary computed tomography angiography (CCTA) verified plaque progression in stented patients. A comparison between diabetic and non-diabetic patients was performed. A total of 98 patients who underwent clinically indicated serial CCTAs arranged within 1 month before and at least 6 months after percutaneous coronary intervention (PCI) were consecutively included. All the subjects were categorized into diabetic group (n = 36) and non-diabetic groups (n = 62). Coronary stenosis extent scores, segment involvement scores (SIS), segment stenosis scores (SSS) at baseline and follow-up CCTA were quantitatively assessed. The prevalence, characteristics and severity of plaque progression was evaluated blindly to the clinical data and compared between the groups. During the median 1.5 year follow up, a larger number of patients (72.2% vs 40.3%, P = 0.002), more non-stented vessels (55.7% vs 23.2%, P < 0.001) and non-stented segments (10.3% vs 4.4%, P < 0.001) showed plaque progression in DM group, compared to non-DM controls. More progressive lesions in DM patients were found to be non-calcified plaques (31.1% vs 12.8%, P = 0.014) or non-stenotic segments (6.6% vs 3.0%, p = 0.005) and were more widely distributed on left main artery (24.2% vs 5.2%, p = 0.007), the right coronary artery (50% vs 21.1%, P = 0.028) and the proximal left anterior artery (33.3% vs 5.1%, P = 0.009) compared to non-DM patients. In addition, DM patients possessed higher numbers of progressive segments per patient, ΔSIS and ΔSSS compared with non-DM individuals (P < 0.001, P = 0.029 and P < 0.001 respectively). A larger number of patients with at least two progressive lesions were found in the DM group (P = 0.006). Multivariate logistic regression analysis demonstrated that DM (OR: 4.81; 95% CI 1.64–14.07, P = 0.004) was independently associated with plaque progression. DM is closely associated with the prevalence and severity of CCTA verified CAD progression. These findings suggest that physicians should pay attention to non-stent segments and the management of non-stent segment plaque progression, particularly to DM patients.     

HIF prolyl hydroxylase inhibition prior to transient focal cerebral ischaemia is neuroprotective in mice

This study investigated the effects of 2‐(1‐chloro‐4‐hydroxyisoquinoline‐3‐carboxamido) acetic acid (IOX3), a selective small molecule inhibitor of hypoxia‐inducible factor (HIF) prolyl hydroxylases, on mouse brains subject to transient focal cerebral ischaemia. Male, 8‐ to 12‐week‐old C57/B6 mice were subjected to 45 min of middle cerebral artery occlusion (MCAO) either immediately or 24 h after receiving IOX3. Mice receiving IOX3 at 20 mg/kg 24 h prior to the MCAO had better neuroscores and smaller blood–brain barrier (BBB) disruption and infarct volumes than mice receiving the vehicle, whereas those having IOX3 at 60 mg/kg showed no significant changes. IOX3 treatment immediately before MCAO was not neuroprotective. IOX3 up‐regulated HIF‐1α, and increased EPO expression in mouse brains. In an in vitro BBB model (RBE4 cell line), IOX3 up‐regulated HIF‐1α and delocalized ZO‐1. Pre‐treating IOX3 on RBE4 cells 24 h before oxygen–glucose deprivation had a protective effect on endothelial barrier preservation with ZO‐1 being better localized, while immediate IOX3 treatment did not. Our study suggests that HIF stabilization with IOX3 before cerebral ischaemia is neuroprotective partially because of BBB protection, while immediate application could be detrimental. These results provide information for studies aimed at the therapeutic activation of HIF pathway for neurovascular protection from cerebral ischaemia.

     

Untangling the relationships among regional occupancy,species traits,and niche characteristics in stream invertebrates

The regional occupancy and local abundance of species are affected by various species traits, but their relative effects are poorly understood. We studied the relationships between species traits and occupancy (i.e., proportion of sites occupied) or abundance (i.e., mean local abundance at occupied sites) of stream invertebrates using small‐grained data (i.e., local stream sites) across a large spatial extent (i.e., three drainage basins). We found a significant, yet rather weak, linear relationship between occupancy and abundance. However, occupancy was strongly related to niche position (NP), but it showed a weaker relationship with niche breadth (NB). Abundance was at best weakly related to these explanatory niche‐based variables. Biological traits, including feeding modes, habit traits, dispersal modes and body size classes, were generally less important in accounting for variation in occupancy and abundance. Our findings showed that the regional occupancy of stream invertebrate species is mostly related to niche characteristics, in particular, NP. However, the effects of NB on occupancy were affected by the measure itself. We conclude that niche characteristics determine the regional occupancy of species at relatively large spatial extents, suggesting that species distributions are determined by environmental variation among sites.     

Surveying biodiversity in protected and managed areas: Algae, macrophytes and macroinvertebrates in boreal forest streams

Extensive surveys of biodiversity in protected and managed areas have not been conducted for a majority of taxonomic groups and ecosystem types, which makes it difficult to assess how large a portion of biodiversity is at least potentially under protection. The situation is the same in boreal regions, and only preliminary analyses of the biodiversity patterns of less well-known organism groups, including many freshwater taxa, within the protected area network have been conducted. We studied patterns of species richness and community composition of algae, macrophytes (bryophytes and vascular plants), and macroinvertebrates of headwater streams draining protected areas and managed forests in a boreal drainage basin in Finland. We found no significant differences in the species richness and community composition of these organism groups between the protected and managed streams. Gamma- and beta-diversity varied strongly among the protected and managed stream groups, yet this variation was contingent on the organism group and the beta-diversity measure used. In general, there was much species turnover within both protected and managed stream groups, masking any between-group differences. However, we found a number of redlisted and rare species in our surveys. Of these species, several macrophyte species occurred more frequently in the protected streams. By contrast, rare species of algae and macrophytes did not generally show such inclinations to the protected streams. We found no strong congruence in species richness or community dissimilarity between algae, macrophytes, and macroinvertebrates, suggesting that the main anthropogenic gradient in terms of forestry is not strong enough to modify stream environmental conditions and thereby shape biodiversity in the focal drainage basin. This finding also suggests that surveys of aquatic biodiversity across protected and managed landscapes should not rely too heavily on the surrogate taxon approach, but instead should consider patterns shown by multiple taxonomic groups that represent biologically and ecologically disparate organisms. Our results indeed suggest that the levels of alpha-, beta-, and gamma-diversity show differing among-taxon responses to forest management and naturalness of headwater streams.