Benthic Predators and Northern Quahog (=Hard Clam) (Mercenaria Mercenaria Linnaeus, 1758) Populations

Increased numbers of benthic predators, especially crabs, have been proposed as a factor contributing to the decline of hard clams (Mercenaria mercenaria Linnaeus, 1758) in Great South Bay, NY. The long-term trend in benthic predators in this system was examined using observations on the distribution and abundance of predators that have been collected by the Town of Islip, NY as part of an annual survey of hard clam populations. The survey began in 1978 and extends to the present and provides concurrent observations of habitat (sediment type, and presence/absence of eelgrass), and hard clam size-frequency distribution and abundance. Predator type and abundance were reported from 1978 to 1981 and 1991 to 2003, which represents one of the most comprehensive benthic predator data sets currently available for any estuarine system. The annual averages of predator abundance in the survey area primarily show interannual fluctuations in abundance. Xanthid crabs (mud crabs, primarily Dispanopeus sayi Smith, 1869) were the numerically dominant predator in the system; blue crabs (Callinectes sapidus Rathbun, 1895) appeared in the late 1990s. Hard clam abundance has declined by 44% since the early 1990s. An Empirical Orthogonal Function (EOF) Analysis of the predator and hard clam data sets showed that fluctuations in predator abundance are: 1) mostly in phase over the survey region and 2) dominated by year-to-year fluctuations in abundance. The EOF results for the hard clams show that hard clam abundance fluctuations are: 1) in phase over the survey region and 2) dominated by a decreasing trend in abundance over the time series. The primary EOF modes essentially were uncoupled, which implies no strong predator-prey interactions between the predators and hard clams. By inference, increasing predator abundance does not appear to be a primary factor producing the long-term decline in hard clam populations. Predation pressure per recruit may still have increased because of declining hard clam population abundance and the concomitant decline in recruitment

Open access series of imaging studies: Longitudinal MRI data in nondemented and demented older adults

The Open Access Series of Imaging Studies (OASIS) is a series of neuroimaging data sets that is publicly available for study and analysis. The present MRI data set consists of a longitudinal collection of 150 subjects aged 60 to 96 all acquired on the same scanner using identical sequences. Each subject was scanned on two or more visits, separated by at least one year for a total of 373 imaging sessions. Subjects were characterized using the Clinical Dementia Rating (CDR) as either nondemented or with very mild to mild Alzheimer‘s disease (AD). 72 of the subjects were characterized as nondemented throughout the study. 64 of the included subjects were characterized as demented at the time of their initial visits and remained so for subsequent scans, including 51 individuals with CDR 0.5 similar level of impairment to individuals elsewhere considered to have ‘mild cognitive impairment’. Another 14 subjects were characterized as nondemented at the time of their initial visit (CDR 0) and were subsequently characterized as demented at a later visit (CDR > 0). The subjects were all right-handed and include both men (n=62) and women (n=88). For each scanning session, 3 or 4 individual T1-weighted MRI scans were obtained. Multiple within-session acquisitions provide extremely high contrast-to-noise making the data amenable to a wide range of analytic approaches including automated computational analysis. Automated calculation of whole brain volume is presented to demonstrate use of the data for measuring differences associated with normal aging and AD

Functional Brain Imaging of Young, Nondemented, and Demented Older Adults

Brain imaging based on functional MRI (fMRI) provides a powerful tool for characterizing age-related changes in functional anatomy. However, between-population comparisons confront potential differences in measurement properties. The present experiment explores the feasibility of conducting fMRI studies in nondemented and demented older adults by measuring hemodynamic response properties in an event-related design. A paradigm involving repeated presentation of sensory-motor response trials was administered to 41 participants (14 young adults, 14 nondemented older adults, and 13 demented older adults). For half of the trials a single sensory-motor event was presented in isolation and in the other half in pairs. Hemodynamic response characteristics to the isolated events allowed basic response properties (e.g., amplitude and variance) between subject groups to be contrasted. The paired events further allowed the summation properties of the hemodynamic response to be characterized. Robust and qualitatively similar activation maps were produced for all subject groups. Quantitative results showed that for certain regions, such as in the visual cortex, there were marked reductions in the amplitude of the hemodynamic response in older adults. In other regions, such as in the motor cortex, relatively intact response characteristics were observed. These results suggest caution should be exhibited in interpreting simple main effects in response amplitude between subject groups. However, across all regions examined, the summation of the hemodynamic response over trials was highly similar between groups. This latter finding suggests that, even if absolute measurement differences do exist between subject groups, relative activation change should be preserved. Designs that rely on group interactions between task conditions, parametric manipulations, or group interactions between regions should provide valuable data for making inferences about functional-anatomic changes between different populations.Psycholog

Differential Effects of Aging and Alzheimer's Disease on Medial Temporal Lobe Cortical Thickness and Surface Area

The volume of parcellated conical regions is a composite measure related to both thickness and surface area. It is not clear whether volumetric decreases in medial temporal lobe (MTL) cortical regions in aging and Alzheimer's disease (AD) are due to thinning, loss of surface area, or both, nor is it clear whether aging and AD differ in their effects on these properties. Participants included 28 Younger Normals, 47 Older Normals, and 29 patients with mild AD. T1-weighted MRI data were analyzed using a novel semi-automated protocol (presented in a companion article) to delineate the boundaries of entorhinal (ERC), perirhinal (PRC), and posterior parahippocampal (PPHC) cortical regions and calculate their mean thickness, surface area, and volume. Compared to Younger Normals, Older Normals demonstrated moderately reduced ERC and PPHC volumes, which were due primarily to reduced surface area. In contrast. the expected AD-related reduction in ERC volume was produced by a large reduction in thickness with minimal additional effect (beyond that of aging) on surface area. PRC and PPHC also showed large AD-related reductions in thickness. Of all these MTL morphometric measures, ERC and PRC thinning were the best predictors of poorer episodic memory performance in AD. Although the volumes of MTL cortical regions may decrease with both aging and AD, thickness is relatively preserved in normal aging, while even in its mild clinical stage, AD is associated with a large degree of thinning of MTL cortex. These differential morphometric effects of aging and AD may reflect distinct biologic processes and ultimately may provide insights into the anatomic substrates of change in memory-related functions of MTL cortex.Psycholog

Expressed sequence tag analysis of genes expressed during development of the tropical abalone Haliotis asinina

The tropical abalone. Haliotis asinina. is,in ideal species to investigate the molecular mechanisms that control development. growth, reproduction and shell formation in all cultured haliotids. Here we describe the analysis of 232 expressed sequence tags (EST) obtained front a developmental H. asinina cDNA library intended for future microarray studies. From this data set we identified 183 unique gene Clusters. Of these, 90 clusters showed significant homology with sequences lodged in GenBank, ranging in function from general housekeeping to signal transduction, gene regulation and cell-cell communication. Seventy-one clusters possessed completely novel ORFs greater than 50 codons in length, highlighting the paucity of sequence data from molluscs and other lophotrochozoans. This study of developmental gene expression in H. asinina provides the foundation for further detailed analyses of abalone growth, development and reproduction

Changes in endosymbiont complexity drive host-level compensatory adaptations in cicadas

Copyright © 2018 Campbell et al. For insects that depend on one or more bacterial endosymbionts for survival, it is critical that these bacteria are faithfully transmitted between insect generations. Cicadas harbor two essential bacterial endosymbionts, "Candidatus Sulcia muelleri" and "Candidatus Hodgkinia cicadicola." In some cicada species, Hodgkinia has fragmented into multiple distinct but interdependent cellular and genomic lineages that can differ in abundance by more than two orders of magnitude. This complexity presents a potential problem for the host cicada, because low-abundance but essential Hodgkinia lineages risk being lost during the symbiont transmission bottleneck from mother to egg. Here we show that all cicada eggs seem to receive the full complement of Hodgkinia lineages, and that in cicadas with more complex Hodgkinia this outcome is achieved by increasing the number of Hodgkinia cells transmitted by up to 6-fold. We further show that cicada species with varying

Open Access Series of Imaging Studies (OASIS): Cross-sectional MRI Data in Young, Middle Aged, Nondemented, and Demented Older Adults

The Open Access Series of Imaging Studies is a series of magnetic resonance imaging data sets that is publicly available for study and analysis. The initial data set consists of a cross-sectional collection of 416 subjects aged 18 to 96 years. One hundred of the included subjects older than 60 years have been clinically diagnosed with very mild to moderate Alzheimer's disease. The subjects are all right-handed and include both men and women. For each subject, three or four individual T1-weighted magnetic resonance imaging scans obtained in single imaging sessions are included. Multiple within-session acquisitions provide extremely high contrast-to-noise ratio, making the data amenable to a wide range of analytic approaches including automated computational analysis. Additionally, a reliability data set is included containing 20 subjects without dementia imaged on a subsequent visit within 90 days of their initial session. Automated calculation of whole-brain volume and estimated total intracranial volume are presented to demonstrate use of the data for measuring differences associated with normal aging and Alzheimer's disease.Psycholog

Physiological effects of tourism and associated food provisioning in an endangered iguana

© The Author 2013. Deliberately feeding wildlife is an increasingly popular tourism-related activity despite a limited understanding of long-term impacts on the species being fed. As a result, tourist behaviours that may have adverse impacts on imperiled species have often been encouraged without the necessary evaluation or oversight. Here, we report the responses of Northern Bahamian Rock Iguanas (Cyclura cychlura) to human-visitation pressure and associated food provisioning. We compared a variety of blood chemistry parameters of iguanas subjected to supplemental feeding at popular tourist destinations with iguanas occurring on islands where supplemental feeding does not take place. We demonstrate that male and female iguanas inhabiting tourist-visited islands where supplemental feeding occurs do not differ in body condition or baseline stress and stress response (determined by corticosterone levels) compared with iguanas from non-visited islands. Both males and females from tourist-visited sites experienced a greater incidence of endoparasitic infection and atypical loose faeces. Indicators of dietary nutrition, including glucose, potassium, and uric acid values, also differed for both sexes from tourist-visited and unvisited islands. Male iguanas from visited islands differed significantly from those on non-visited islands in calcium, cholesterol, cobalt, copper, magnesium, packed cell volume, selenium, and triglyceride concentrations, whereas female iguanas from visited islands differed significantly in ionized calcium. Although the interpretation of these differences is challenging, chronic biochemical stressors could compromise individual health over time or decrease survivorship during periods of environmental stress. We suggest protocols that can be adopted throughout the region to ensure that supplemental feeding has fewer impacts on these long-lived iguanas