Habitat selection of resident and non-resident gray wolves: implications for habitat connectivity.

Habitat selection studies facilitate assessing and predicting species distributions and habitat connectivity, but habitat selection can vary temporally and among individuals, which is often ignored. We used GPS telemetry data from 96 Gray wolves (Canis lupus) in the western Great Lakes region of the USA to assess differences in habitat selection while wolves exhibited resident (territorial) or non-resident (dispersing or floating) movements and discuss implications for habitat connectivity. We used a step-selection function (SSF) to assess habitat selection by wolves exhibiting resident or non-resident movements, and modeled circuit connectivity throughout the western Great Lakes region. Wolves selected for natural land cover and against areas with high road densities, with no differences in selection among wolves when resident, dispersing, or floating. Similar habitat selection between resident and non-resident wolves may be due to similarity in environmental conditions, when non-resident movements occur largely within established wolf range rather than near the periphery or beyond the species range. Alternatively, non-resident wolves may travel through occupied territories because higher food availability or lower human disturbance outweighs risks posed by conspecifics. Finally, an absence of differences in habitat selection between resident and non-resident wolf movements may be due to other unknown reasons. We recommend considering context-dependency when evaluating differences in movements and habitat use between resident and non-resident individuals. Our results also provide independent validation of a previous species distribution model and connectivity analysis suggesting most potential wolf habitat in the western Great Lakes region is occupied, with limited connectivity to unoccupied habitat.

Distribution model transferability for a wide-ranging species, the Gray Wolf.

Using existing data can be a reliable and cost-effective way to predict species distributions, and particularly useful for recovering or expanding species. We developed a current gray wolf (Canis lupus) distribution model for the western Great Lakes region, USA, and evaluated the spatial transferability of single-state models to the region. This study is the first assessment of transferability in a wide-ranging carnivore, as well as one of few developed for large spatial extents. We collected 3500 wolf locations from winter surveys in Minnesota (2017-2019), Wisconsin (2019-2020), and Michigan (2017-2020). We included 10 variables: proportion of natural cover, pastures, and crops; distance to natural cover, agriculture, developed land, and water; major and minor road density; and snowfall (1-km res.). We created a regional ensemble distribution by weight-averaging eight models based on their performance. We also developed single-state models, and estimated spatial transferability using two approaches: state cross-validation and extrapolation. We assessed performance by quantifying correlations, receiver operating characteristic curves (ROC), sensitivities, and two niche similarity indices. The regional area estimated to be most suitable for wolves during winter (threshold = maximum sensitivity/specificity) was 106,465 km2 (MN = 48,083 km2, WI = 27,757 km2, MI = 30,625 km2) and correctly predicted 88% of wolf locations analyzed. Increasing natural cover and distance to crops were consistently important for determining regional and single-state wolf distribution. Extrapolation (vs. cross-validation) produced results with the greatest performance metrics, and were most similar to the regional model, yet good internal performance was unrelated to greater extrapolation performance. Factors influencing species distributions are scale-dependent and can vary across areas due to behavioral plasticity. When extending inferences beyond the current occurrence of individuals, assessing variation in ecology such as habitat selection, as well as methodological factors including model performance, will be critical to avoid poor scientific interpretations and develop effective conservation applications. In particular, accurate distribution models for recovering or recovered carnivores can be used to develop plans for habitat management, quantify potential of unoccupied habitat, assess connectivity modeling, and mitigate conflict, facilitating long-term species persistence.

Interleukin-6 in tear fluid after photorefractive keratectomy and its effects on keratocytes in culture.

PURPOSE: To investigate the participation of interleukin-6 (IL-6) after photorefractive keratectomy (PRK) and its possible roles and sources in corneal wound healing. METHODS: IL-6, levels were measured in the tear fluids of patients before and after PRK and in conditioned media of human corneal epithelial cells and keratocytes. Its effects on total collagen and collagen-type synthesis by keratocytes were studied with a 3H-proline incorporation assay and Northern blot analysis. Zymography was used to evaluate the metalloproteinase content in the conditioned medium of IL-6-stimulated keratocytes. RESULTS: IL-6 is present in the tear fluid samples after photorefractive keratectomy, possibly synthesized by epithelial cells and keratocytes. CONCLUSIONS: IL-6 stimulates collagen synthesis in general and collagen type I in particular. Furthermore, it reduces the production of MMP-2, the latent form of the metalloproteinase, by cultured keratocytes. The results suggest that IL-6 might be regarded as a mediator involved in corneal healing after excimer laser.

Bradykinin-induced in vitro contraction of rat mesangial cells via a B2 receptor type.

The effect of bradykinin (BK) on the contraction of rat mesangial cells (MC) was compared with that of various vasoactive agents. BK induced a dose-dependent contraction [one-half maximal effective dose (ED50) = 50 nM] inhibited by the B2 antagonist, HOE-140 (ED50 = 10 nM). BK-induced MC contraction was independent of extracellular calcium and was reduced by inhibition of protein kinase C (PKC). Neomycin completely prevented the increase in intracellular calcium and the formation of inositol 1,4,5-trisphosphate induced by BK but only reduced cell contraction. Inhibition of prostaglandin (PG) formation and administration of the endoperoxide antagonist SQ-27427 also partly decreased the effect of BK. Interestingly, only the addition of both neomycin and mepacrine resulted in a complete inhibition of cell contraction. These results suggest that BK, via a B2-kinin receptor, induces contraction of MC through two distinct mechanisms, one associated to the phospholipase C pathway and subsequent activation of PKC and the second one dependent on PG formation. These in vitro effects may be relevant in explaining the effects of BK and converting enzyme inhibitors on glomerular hemodynamics.

Evidence for existence of two distinct bradykinin receptors on rat mesangial cells.

We investigated the possible presence of bradykinin (BK) B1 receptor on rat mesangial cells (MC) by binding studies and by the effect of the B1 agonist des-Arg9-BK on intracellular calcium concentration ([Ca2+]i) and DNA synthesis in comparison with the effects of BK. Binding studies demonstrated specific, saturable binding for des-Arg9-[3H]BK inhibited by B1 but not by B2 antagonists. Scatchard analysis revealed a single class of B1 binding site with a maximum density of 15 fmol/mg protein and an affinity of 8.7 +/- 2.4 nM. Saturation and competition studies of 125I-[Tyr0]BK demonstrated the presence of two classes of B2 binding sites [dissociation constant (Kd) = 0.1 and 4 nM, respectively]. On fura-2-loaded adherent MC, both des-Arg9-BK and BK induced a biphasic increase (a transient enhancement followed by a sustained phase) in [Ca2+]i, both in primary culture and in cloned MC. Both the transient and sustained phases of [Ca2+]i induced by des-Arg9-BK were dose dependent, whereas BK induced a transient dose-dependent rise in [Ca2+]i, but the sustained phase remained constant. The increases in [Ca2+]i induced by des-Arg9-BK and BK were specifically abolished by B1 and B2 receptor antagonists, respectively, and showed homologous but not heterologous desensitization. Des-Arg9-BK and BK induced a significant proliferation (tested by cell counting and [3H]thymidine incorporation) of quiescent MC. Furthermore, the effects of des-Arg9-BK and BK were additive on Ca2+ mobilization but not on mitogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)

[Induction of chemotaxis by soluble immune complexes]. / Propriétés chimiotactiques de complexes immuns solubles

These complexes, obtained either by adding antigen in excess to immune sera or by redissolving an immune precipitate with antigen, could in the presence of fresh serum stimulate PMN leucocytes to migrate. Complexes with a molecular composition Ab1Ag1 (ot C fixing) showed higher activity than complexes of larger size. The experiments suggest that they activate some sequence of the contact system of coagulation.