MOVEMENT OF EELWORMS: V. OBSERVATIONS ON APHELENCHOIDES RITZEMA-BOSI (SCHWARTZ, 1912) STEINER, 1932 ON FLORISTS' CHRYSANTHEMUMS

Adults of Aphelenchoides ritzema-bosi tend to migrate up the stems of chrysanthemum plants in stationary water films possibly by a negatively geotropic response. A current of water down the stem opposes such an upward movement. Greatest mobility occurred in thick films of water in places with a high concentration of epidermal hairs as at the top of the stem and on the undersurface of leaves. Ciné films of movement in thick and thin films showed that there were fundamental differences in the type of locomotion in these two environments. Invasion of leaves via stomata was observed and the method of movement is described. The presence of A. ritzema-bosi in leaves appears to render the epidermis permeable to water. During dry weather there is little movement inside the leaf, but after rainfall activity increases as water enters the leaf. Spread of eelworm infestation in the leaf occurs in the mesophyll and across veins although initially these act as barriers. Emergence occurs via the stomata, chiefly on the undersurface. When the leaf is wet, about 50% of the eelworms emerge in the first hour. During wet weather many eelworms were recovered from the surfaces of leaves and it is suggested that eelworms spread mostly under these conditions.     

Aerial Surveys for Estimating Wild Turkey Abundance in the Texas Rolling Plains

Abstract: Aerial surveys have been used to estimate abundance of several wild bird species including wild turkeys (Meleagris gallopavo). We used inflatable turkey decoys at 3 study sites in the Texas Rolling Plains to simulate Rio Grande wild turkey (M. g. intermedia) flocks. We evaluated detectability of flocks and errors in counting flock size during fixed-wing (Cessna 172) aerial surveys using logistic and linear regression models. Flock detectability was primarily influenced by flock size and vegetative cover, and errors in counting flock size were primarily influenced by size of flocks. We conducted computer simulations to evaluate the accuracy and precision of fixed-wing aerial surveys and examined power to detect trends in population change. Our simulations suggested abundance estimates from fixed-wing aerial surveys may be underestimated by 10-15% (2.0-4.8% CV). Power analyses suggested that fixed-wing aerial surveys can provide sufficient power (>0.80) to detect a population change of 10-25% over a 4-5-year period. We concluded fixed-wing aerial surveys are feasible on ecoregion scales.     

Rio Grande Wild Turkey Habitat Selection in the Southern Great Plains

ABSTRACT We recorded telemetry locations from 1,129 radiotagged turkeys (Meleagris gallopavo intermedia) on 4 study areas in the Texas Panhandle and southwestern Kansas, USA, from 2000 to 2004. Analyses of telemetry locations indicated both sexes selected riparian vegetative zones. Females did not select grazed or nongrazed pastures for daily movements. However, females did select nongrazed pastures for nest sites on 2 study areas and males selected for grazed pastures at one study area during the breeding season. We compared nest sites (n = 351) to random sites using logistic regression, which indicated height of visual obstruction, percent canopy cover, and percent bare ground provided the highest predictive power (P ≤ 0.003) for characteristics describing nest-site selection. Nest-site vegetative characteristics between vegetative zones differed primarily in composition: upland zone nest sites had more (P ≤ 0.001) shrubs and riparian zone nest sites had more (P ≤ 0.001) grass. There were no differences in measured nest site vegetative characteristics between pasture types, but there were differences between available nesting cover in grazed and nongrazed pastures. Random plots in grazed pastures had less grass cover (P ≤ 0.001) and more bare ground (P = 0.002). Because of cattle impacts on average grass height and availability, grazing would likely have the highest impact on nesting in riparian zones due to turkey use of grass as nesting cover. An appropriate grazing plan to promote Rio Grande turkey nesting habitat would include grazing upland zones in the spring, when it likely has little impact on nesting-site selection, and grazing riparian zones following breeding season completion. Grazing at light to moderate intensities with periods of rest did not affect male turkey pasture use and may have continued to maintain open areas used by male turkeys for displaying purposes.     

Encounter Rates From Road-Based Surveys of Rio Grande Wild Turkeys in Texas

ABSTRACT Traditional index-based techniques have indicated declines in Rio Grande wild turkey (Meleagris gallopavo intermedia; hereafter, wild turkey) populations across much of Texas, USA. However, population indices can be unreliable. Research has indicated that road-based surveys may be an efficacious technique for monitoring wild turkey populations on an ecoregion level. Therefore, our goal was to evaluate applicability of road-based distance sampling in the Cross Timbers, Edwards Plateau, Rolling Plains, and South Texas ecoregions of Texas. We conducted road-based surveys in each ecoregion during December 2007—March 2008 to estimate wild turkey flock encounter rates and to determine survey effort (i.e., km of roads) required to obtain adequate sample sizes for distance sampling in each ecoregion. With simulations using inflatable turkey decoys, we also evaluated effects of distance to a flock, flock size, and vegetative cover on turkey flock detectability. Encounter rates of wild turkey flocks from road-based surveys varied from 0.1 (95% CI = 0.0–0.6) to 2.2 (95% CI = 0.8–6.0) flocks/100 km surveyed. Encounter rates from surveys restricted to riparian communities (i.e., areas ≤1 km from a river or stream) varied from 0.2 (95% CI = 0.1–0.6) to 2.9 (95% CI = 1.5–6.7) flocks/100 km surveyed. Flock detection probabilities from field simulations ranged from 22.5% (95% CI = 16.3–29.8%) to 25.0% (95% CI = 13.6–39.6%). Flock detection probabilities were lower than expected in all 4 ecoregions, which resulted in low encounter rates. Estimated survey effort required to obtain adequate sample sizes for distance sampling ranged from 2,765 km (95% CI = 2,597–2,956 km) in the Edwards Plateau to 37,153 km (95% CI = 12,861–107,329 km) in South Texas. When we restricted road-based surveys to riparian communities, estimated survey effort ranged from 2,222 km (95% CI = 2,092–2,370 km) in the Edwards Plateau to 22,222 km (95% CI = 19,782–25,349 km) in South Texas.     

Cholesterol accumulation caused by low density lipoprotein receptor deficiency or a cholesterol-rich diet results in ectopic bone formation during experimental osteoarthritis

Introduction

Osteoarthritis (OA) is associated with the metabolic syndrome, however the underlying mechanisms remain unclear. We investigated whether low density lipoprotein (LDL) accumulation leads to increased LDL uptake by synovial macrophages and affects synovial activation, cartilage destruction and enthesophyte/osteophyte formation during experimental OA in mice.

Methods

LDL receptor deficient (LDLr^−/−) mice and wild type (WT) controls received a cholesterol-rich or control diet for 120 days. Experimental OA was induced by intra-articular injection of collagenase twelve weeks after start of the diet. OA knee joints and synovial wash-outs were analyzed for OA-related changes. Murine bone marrow derived macrophages were stimulated with oxidized LDL (oxLDL), whereupon growth factor presence and gene expression were analyzed.

Results

A cholesterol-rich diet increased apolipoprotein B (ApoB) accumulation in synovial macrophages. Although increased LDL levels did not enhance thickening of the synovial lining, S100A8 expression within macrophages was increased in WT mice after receiving a cholesterol-rich diet, reflecting an elevated activation status. Both a cholesterol-rich diet and LDLr deficiency had no effect on cartilage damage; in contrast, ectopic bone formation was increased within joint ligaments (fold increase 6.7 and 6.1, respectively). Moreover, increased osteophyte size was found at the margins of the tibial plateau (4.4 fold increase after a cholesterol-rich diet and 5.3 fold increase in LDLr^−/− mice). Synovial wash-outs of LDLr^−/− mice and supernatants of macrophages stimulated with oxLDL led to increased transforming growth factor-beta (TGF-β) signaling compared to controls.

Conclusions

LDL accumulation within synovial lining cells leads to increased activation of synovium and osteophyte formation in experimental OA. OxLDL uptake by macrophages activates growth factors of the TGF-superfamily.