Assessment of estradiol influence on spatial tasks and hippocampal CA1 spines: evidence that the duration of hormone deprivation after ovariectomy compromises 17beta-estradiol effectiveness in altering CA1 spines

Two pulses of 17β-estradiol (10 µg) are commonly used to increase hippocampal CA1 apical dendritic spine density and alter spatial performance in ovariectomized (OVX) female rats, but rarely are the measures combined. The goal of this study was to use this two-pulse injection protocol repeatedly with intervening wash-out periods in the same rats to: 1) measure spatial ability using different tasks that require hippocampal function and 2) determine whether ovarian hormone depletion for an extended 10-week period reduces 17β-estradiol's effectiveness in elevating CA1 apical dendritic spine density. Results showed that two injections of 10 µg 17β-estradiol (72 and 48 h prior to testing and timed to maximize CA1 apical spine density at behavioral assessment) corresponded to improved spatial memory performance on object placement. In contrast, two injections of 5 µg 17β-estradiol facilitated spatial learning on the water maze compared to rats given two injections of 10 µg 17β-estradiol or the sesame oil vehicle. Neither 17β-estradiol dose altered Y-maze performance. As expected, the intermittent two-pulse injection protocol increased CA1 apical spine density, but 10 weeks of OVX without estradiol treatment decreased the effectiveness of 10 µg 17β-estradiol to increase CA1 apical spine density. Moreover, two pulses of 5 µg 17β-estradiol injected intermittently failed to alter CA1 apical spine density and decreased basal spine density. These results demonstrate that extended time without ovarian hormones reduces 17β-estradiol's effectiveness to increase CA1 apical spine density. Collectively, these findings highlight the complex interactions among estradiol, CA1 spine density/morphology, and task requirements, all of which contribute to behavioral outcomes.     

Two Years Later: Journals Are Not Yet Enforcing the ARRIVE Guidelines on Reporting Standards for Pre-Clinical Animal Studies

There is growing concern that poor experimental design and lack of transparent reporting contribute to the frequent failure of pre-clinical animal studies to translate into treatments for human disease. In 2010, the Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines were introduced to help improve reporting standards. They were published in PLOS Biology and endorsed by funding agencies and publishers and their journals, including PLOS, Nature research journals, and other top-tier journals. Yet our analysis of papers published in PLOS and Nature journals indicates that there has been very little improvement in reporting standards since then. This suggests that authors, referees, and editors generally are ignoring guidelines, and the editorial endorsement is yet to be effectively implemented.     

The Impact of Short,Irregular Sleep Opportunities at Sea on the Alertness of Marine Pilots Working Extended Hours

The aim of this study was to examine the impact of brief, unscheduled naps during work periods on alertness and vigilance in coastal pilots along the Great Barrier Reef. On certain routes, the duration of the work period can extend well beyond 24 h. Seventeen coastal pilots volunteered for the study, representing almost one‐third of the population. Participants collected sleep/wake and performance data for 28 days using a sleep and work diary and the palm PVT task. The average length of sleep on board was 1.4±1.0 h. Naps were taken regularly such that the average length of time awake between sleep periods on board a ship was 5.3±4.3 h. There was no change in mean reaction time across either the length of a pilotage or across the 24 h day. The results indicate that even though the naps were taken opportunistically, they tended to cluster at the high sleep propensity times. Further, frequent, opportunistic naps appeared to provide adequate recovery such that PVT performance remained stable. Pilots did report increases in subjective fatigue ratings at certain times of the 24 h day and at the end of a work period; however, these did not reach the high range. The fatigue‐risk minimization strategies employed by the Australian Maritime Safety Authority and the coastal pilots appear to be effective in maintaining alertness and vigilance while at work aboard ships.     

A role for indels in the evolution of Cro protein folds

Insertions and deletions in protein sequences, or indels, can disrupt structure and may result in changes in protein folds during evolution or in association with alternative splicing. Pfl 6 and Xfaso 1 are two proteins in the Cro family that share a common ancestor but have different folds. Sequence alignments of the two proteins show two gaps, one at the N terminus, where the sequence of Xfaso 1 is two residues shorter, and one near the center of the sequence, where the sequence of Pfl 6 is five residues shorter. To test the potential importance of indels in Cro protein evolution, we generated hybrid variants of Pfl 6 and Xfaso 1 with indels in one or both regions, chosen according to several plausible sequence alignments. All but one deletion variant completely unfolded both proteins, showing that a longer N‐terminal sequence was critical for Pfl 6 folding and a longer central region sequence was critical for Xfaso 1 folding. By contrast, Xfaso 1 tolerated a longer N‐terminal sequence with little destabilization, and Pfl 6 tolerated central region insertions, albeit with substantial effects on thermal stability and some perturbation of the surrounding structure. None of the mutations appeared to convert one stable fold into the other. On the basis of this two‐protein comparison, short insertion and deletion mutations probably played a role in evolutionary fold change in the Cro family, but were also not the only factors. Proteins 2013; 81:1988–1996. © 2013 Wiley Periodicals, Inc.     

Characterization of four TCE-dechlorinating microbial enrichments grown with different cobalamin stress and methanogenic conditions

To investigate the important supportive microorganisms responsible for trichloroethene (TCE) bioremediation under specific environmental conditions and their relationship with Dehalococcoides (Dhc), four stable and robust enrichment cultures were generated using contaminated groundwater. Enrichments were maintained under four different conditions exploring two parameters: high and low TCE amendments (resulting in inhibited and uninhibited methanogenic activity, respectively) and with and without vitamin B₁₂ amendment. Lactate was supplied as the electron donor. All enrichments were capable of reductively dechlorinating TCE to vinyl chloride and ethene. The dechlorination rate and ethene generation were higher, and the proportion of electrons used for dechlorination increased when methanogenesis was inhibited. Biologically significant cobalamin biosynthesis was detected in the enrichments without B₁₂ amendment. Comparative genomics using a genus-wide microarray revealed a Dhc genome similar to that of strain 195 in all enrichments, a strain that lacks the major upstream corrin ring biosynthesis pathway. Seven other bacterial operational taxonomic units (OTUs) were detected using clone libraries. OTUs closest to Pelosinus, Dendrosporobacter, and Sporotalea (PDS) were most dominant. The Clostridium-like OTU was most affected by B₁₂ amendment and active methanogenesis. Principal component analysis revealed that active methanogenesis, rather than vitamin B₁₂ limitation, exerted a greater effect on the community structures even though methanogens did not seem to play an essential role in providing corrinoids to Dhc. In contrast, acetogenic bacteria that were abundant in the enrichments, such as PDS and Clostridium sp., may be potential corrinoid providers for Dhc.     

HPV16 Seropositivity and Subsequent HPV16 Infection Risk in a Naturally Infected Population: Comparison of Serological Assays

Background

Several serological assays have been developed to detect antibodies elicited against infections with oncogenic human papillomavirus (HPV) type 16. The association between antibody levels measured by various assays and subsequent HPV infection risk may differ. We compared HPV16-specific antibody levels previously measured by a virus-like particle (VLP)-based direct enzyme-linked immunoassay (ELISA) with levels measured by additional assays and evaluated the protection against HPV16 infection conferred at different levels of the assays.

Methodology/Principal Findings

Replicate enrollment serum aliquots from 388 unvaccinated women in the control arm of the Costa Rica HPV vaccine trial were measured for HPV16 seropositivity using three serological assays: a VLP-based direct ELISA; a VLP-based competitive Luminex immunoassay (cLIA); and a secreted alkaline phosphatase protein neutralization assay (SEAP-NA). We assessed the association of assay seropositivity and risk of subsequent HPV16 infection over four years of follow-up by calculating sampling-adjusted odds ratios (OR) and HPV16 seropositivity based on standard cutoff from the cLIA was significantly associated with protection from subsequent HPV16 infection (OR = 0.48, CI = 0.27–0.86, compared with seronegatives). Compared with seronegatives, the highest seropositive tertile antibody levels from the direct ELISA (OR = 0.53, CI = 0.28–0.90) as well as the SEAP-NA (OR = 0.20, CI = 0.06, 0.64) were also significantly associated with protection from HPV16 infection.

Conclusions/Significance

Enrollment HPV16 seropositivity by any of the three serological assays evaluated was associated with protection from subsequent infection, although cutoffs for immune protection were different. We defined the assays and seropositivity levels after natural infection that better measure and translate to protective immunity.