Mountain goat survival in coastal Alaska: Effects of age,sex, and climate

Ecological theory predicts that individual survival should vary between sex and age categories due to differences in allocation of nutritional resources for growth and reproductive activities. During periods of environmental stress, such relationships may be exacerbated, and affect sex and age classes differently. We evaluated support for hypotheses about the relative roles of sex, age, and winter and summer climate on the probability of mountain goat (Oreamnos americanus) survival in coastal Alaska. Specifically, we used known-fates analyses (Program MARK) to model the effects of age, sex, and climatic variation on survival using data collected from 279 radio-marked mountain goats (118 M, 161 F) in 9 separate study areas during 1977–2008. Models including age, sex, winter snowfall, and average daily summer temperature (during Jul–Aug) best explained variation in survival probability of mountain goats. Specifically, our findings revealed that old animals (9+ yr) have lower survival than younger animals. In addition, males tended to have lower survival than females, though differences only existed among prime-aged adult (5–8 yr) and old (9+ yr) age classes. Winter climate exerted the strongest effects on mountain goat survival; summer climate, however, was significant and principally influenced survival during the following winter via indirect effects. Furthermore, old animals were more sensitive to the effects of winter conditions than young or prime-aged animals. These findings detail how climate interacts with sex and age characteristics to affect mountain goat survival. Critically, we provide baseline survival rate statistics across various age, sex, and climate scenarios. These data will assist conservation and management of mountain goats by enabling detailed, model-based demographic forecasting of human and/or climate-based population impacts. © 2011 The Wildlife Society.     

Loss of Rare Fish Species from Tropical Floodplain Food Webs Affects Community Structure and Ecosystem Multifunctionality in a Mesocosm Experiment

Experiments with realistic scenarios of species loss from multitrophic ecosystems may improve insight into how biodiversity affects ecosystem functioning. Using 1000 L mesocoms, we examined effects of nonrandom species loss on community structure and ecosystem functioning of experimental food webs based on multitrophic tropical floodplain lagoon ecosystems. Realistic biodiversity scenarios were developed based on long-term field surveys, and experimental assemblages replicated sequential loss of rare species which occurred across all trophic levels of these complex food webs. Response variables represented multiple components of ecosystem functioning, including nutrient cycling, primary and secondary production, organic matter accumulation and whole ecosystem metabolism. Species richness significantly affected ecosystem function, even after statistically controlling for potentially confounding factors such as total biomass and direct trophic interactions. Overall, loss of rare species was generally associated with lower nutrient concentrations, phytoplankton and zooplankton densities, and whole ecosystem metabolism when compared with more diverse assemblages. This pattern was also observed for overall ecosystem multifunctionality, a combined metric representing the ability of an ecosystem to simultaneously maintain multiple functions. One key exception was attributed to time-dependent effects of intraguild predation, which initially increased values for most ecosystem response variables, but resulted in decreases over time likely due to reduced nutrient remineralization by surviving predators. At the same time, loss of species did not result in strong trophic cascades, possibly a result of compensation and complexity of these multitrophic ecosystems along with a dominance of bottom-up effects. Our results indicate that although rare species may comprise minor components of communities, their loss can have profound ecosystem consequences across multiple trophic levels due to a combination of direct and indirect effects in diverse multitrophic ecosystems.     

Black Bears Select Large Woody Structures for Dens in Southeast Alaska

Timber interests target coastal temperate rainforests, and within them stands composed of large trees potentially selected by American black bears (Ursus americanus) for denning. We identified the location of 75 black bear dens (used ≥14 days) in an intensively logged area on Prince of Wales Island, Alaska, USA. We ground-visited a subset (n = 43) of these sites to measure the diameter of living trees and woody structures used by black bears for denning. We contrasted dens with random trees available in the study area in a series of models to characterize black bear den selection. All but 1 of 43 ground-visited dens were located within woody structures, and all but 2 of these structures were >1 m diameter at breast height (dbh). We built resource selection functions (RSFs) to investigate black bear den selection across a range of spatial scales, though estimated selection was generally scale invariant. Black bears strongly selected large-diameter woody structures (dead or alive) as dens at the home-range scale, with the estimated relative strength of selection (RSS) for a 2-m-diameter tree approximately 166 times that of a 1-m-diameter tree. The estimated RSS of logged forest was unexpectedly greater (2.75 times) than that of the remaining commercially valuable old-growth forest. Selection for den structures within stumps in previously logged stands suggests features of the woody structure may be of greater importance to black bears selecting dens than attributes of the surrounding forest. There was no observed correlation between bear den selection and second-growth age, indicating that stumps may persist as suitable dens well after logging. Because denning is an important part of their life history and the denning structures used by black bears on Prince of Wales Island will eventually decay, retaining habitat value for bears in areas intensively managed for timber harvest requires strategies to recruit very large, old trees throughout the landscape. © 2021 The Wildlife Society.     

Mesenchymal Stem Cells Derived from Adipose Tissue vs Bone Marrow: In Vitro Comparison of Their Tropism towards Gliomas

Introduction

Glioblastoma is the most common primary malignant brain tumor, and is refractory to surgical resection, radiation, and chemotherapy. Human mesenchymal stem cells (hMSC) may be harvested from bone marrow (BMSC) and adipose (AMSC) tissue. These cells are a promising avenue of investigation for the delivery of adjuvant therapies. Despite extensive research into putative mechanisms for the tumor tropism of MSCs, there remains no direct comparison of the efficacy and specificity of AMSC and BMSC tropism towards glioma.

Methods

Under an IRB-approved protocol, intraoperative human Adipose MSCs (hAMSCs) were established and characterized for cell surface markers of mesenchymal stem cell origin in conjunction with the potential for tri-lineage differentiation (adipogenic, chondrogenic, and osteogenic). Validated experimental hAMSCs were compared to commercially derived hBMSCs (Lonza) and hAMSCs (Invitrogen) for growth responsiveness and glioma tropism in response to glioma conditioned media obtained from primary glioma neurosphere cultures.

Results

Commercial and primary culture AMSCs and commercial BMSCs demonstrated no statistically significant difference in their migration towards glioma conditioned media in vitro. There was statistically significant difference in the proliferation rate of both commercial AMSCs and BMSCs as compared to primary culture AMSCs, suggesting primary cultures have a slower growth rate than commercially available cell lines.

Conclusions

Adipose- and bone marrow-derived mesenchymal stem cells have similar in vitro glioma tropism. Given the well-documented ability to harvest larger numbers of AMSCs under local anesthesia, adipose tissue may provide a more efficient source of MSCs for research and clinical applications, while minimizing patient morbidity during cell harvesting.     

Oncogenic comparison of human papillomavirus type 58 E7 variants

Human papillomavirus 58 (HPV58) ranks the second or third in East Asian cervical cancers. Current studies on HPV58 are scarce and focus on the prototype. Previously, we identified the three most common circulating HPV58 E7 strains contained amino acid alterations: G41R/G63D (51%), T20I/G63S (22%) and T74A/D76E (14%) respectively. Among them, the T20I/G63S variant (V1) had a stronger epidemiological association with cervical cancer. We therefore suggested that V1 possessed stronger oncogenicity than the other two variants. Here, we performed phenotypic assays to characterize and compare their oncogenicities with HPV58 E7 prototype. Our results showed that overexpression of V1 conferred a higher colony‐forming ability to primary murine epithelial cells than prototype (P < 0.05) and other variants, implicating its higher immortalising potential. Further experiments showed that both V1 and prototype enhanced the anchorage‐independent growth of NIH/3T3 cells (P < 0.001), implicating their stronger transforming power than the two other variants. Moreover, they possessed an increased ability to degrade pRb (P < 0.001), which is a major effector pathway of E7‐driven oncogenesis. Our work represents the first study to compare the oncogenicities of HPV58 E7 prototype and variants. These findings deepened our understanding of HPV58 and might inform clinical screening and follow‐up strategy.     

Sequential colonization by river periphyton analysed by microscopy and molecular fingerprinting

1. An artificial glass substratum was incubated in the River Danube for a period of 28 days in order to detect the sequential colonization of microorganisms.
2. Light and fluorescent microscopy showed that microalgae and the picoalgal fraction on the slides increased rapidly over the first 2 weeks of colonization. Diatoms were numerically the most abundant component of the periphyton and their species richness and diversity increased rapidly in the early phase of colonization whereas diversity subsequently increased moderately.
3. Evenness of the diatom community was initially high, lower in the intermediate phase and again higher later on. Succession involving early, intermediate and late colonizer species was observed. Community composition during the first 5 days of colonization was very different from later stages whereas there were only minor changes subsequently.
4. Molecular community analysis by means of terminal restriction fragment length polymorphism analysis of PCR amplified 16S rRNA and 18S rRNA genes pointed to even larger differences between the composition of samples obtained early and late in the period.
5. The number of 18S rRNA and 16S rRNA terminal restriction fragments (T-RF-s) was variable over the colonization period and the fragment patterns of both the bacterial and eukaryotic portion of the microbial community were variable, with most T-RF-s unique to a single sample, suggesting a wide diversity and dynamic properties of periphytic organisms.     

Persistence of wild-type virus and lack of temporal structure in the latent reservoir for human immunodeficiency virus type 1 in pediatric patients with extensive antiretroviral exposure

Although highly active antiretroviral therapy (HAART) for human immunodeficiency virus type 1 (HIV-1) infection can reduce levels of HIV-1 RNA in plasma to below the limit of detection, replication-competent forms of the virus persist in all infected individuals. One form of persistence involves a stable reservoir of latent but potentially infectious virus that resides in resting memory CD4(+) T cells. The mechanisms involved in maintaining this latent reservoir are incompletely understood. In the present study, we examined the dynamic characteristics of this reservoir in a cohort of children who developed drug-resistant HIV-1 as a result of extensive exposure to inadequately suppressive one- or two-drug regimens prior to the advent of HAART. We have previously shown that drug-resistant viruses selected by nonsuppressive pre-HAART regimens can enter and persist in this reservoir. We have extended these findings here by demonstrating that archival wild-type HIV-1 persists in this reservoir despite the fact that in these patients drug-resistant mutants have been favored by the selective conditions for many years. Phylogenetic analysis of replication-competent viruses persisting in resting CD4(+) T cells revealed a striking lack of temporal structure in the sense that isolates obtained at later time points did not show greater sequence divergence than isolates from earlier time points. The persistence of drug-sensitive virus and the lack of temporal structure in the latent reservoir provide genetic evidence for the idea that HIV-1 can persist in a latent form free of selective pressure from antiretroviral drugs in long-lived resting memory CD4(+) T cells. Although there may be other mechanisms for viral persistence, this stable pool of latently infected cells is of significant concern because of its potential to serve as a lasting source of replication-competent viruses, including the infecting wild-type form and all drug-resistant variants that have arisen subsequently.     

Descriptions of melissopalynological methods involving centrifugation should include data for calculating Relative Centrifugal Force (RCF) or should express data in units of RCF or gravities (g)

Techniques of pollen recovery involving centrifugation of honey pollen (melissopalynology) described in certain publications are difficult to 1) reproduce and 2) compare to other melissopalynological methods because dimensions of the centrifuge rotor were not described. Centrifugation data should be stated either in units of Relative Centrifugal Force (RCF) or gravities (g), or the data should be stated so RCF can be calculated using revolutions per minute (RPM) and the dimensions of the centrifuge rotor.