Among-population variation in telomere regulatory proteins and their potential role as hidden drivers of intraspecific variation in life history

Biologists aim to explain patterns of growth, reproduction and ageing that characterize life histories, yet we are just beginning to understand the proximate mechanisms that generate this diversity. Existing research in this area has focused on telomeres but has generally overlooked the telomere's most direct mediator, the shelterin protein complex. Shelterin proteins physically interact with the telomere to shape its shortening and repair. They also regulate metabolism and immune function, suggesting a potential role in life history variation in the wild. However, research on shelterin proteins is uncommon outside of biomolecular work. Intraspecific analyses can play an important role in resolving these unknowns because they reveal subtle variation in life history within and among populations. Here, we assessed ecogeographic variation in shelterin protein abundance across eight populations of tree swallow (Tachycineta bicolor) with previously documented variation in environmental and life history traits. Using the blood gene expression of four shelterin proteins in 12-day-old nestlings, we tested the hypothesis that shelterin protein gene expression varies latitudinally and in relation to both telomere length and life history. Shelterin protein gene expression differed among populations and tracked non-linear variation in latitude: nestlings from mid-latitudes expressed nearly double the shelterin mRNA on average than those at more northern and southern sites. However, telomere length was not significantly related to latitude. We next assessed whether telomere length and shelterin protein gene expression correlate with 12-day-old body mass and wing length, two proxies of nestling growth linked to future fecundity and survival. We found that body mass and wing length correlated more strongly (and significantly) with shelterin protein gene expression than with telomere length. These results highlight telomere regulatory shelterin proteins as potential mediators of life history variation among populations. Together with existing research linking shelterin proteins and life history variation within populations, these ecogeographic patterns underscore the need for continued integration of ecology, evolution and telomere biology, which together will advance understanding of the drivers of life history variation in nature.

What happens when the lights are left on? Transcriptomic and phenotypic habituation to light pollution

Artificial light at night (ALAN) is a ubiquitous pollutant worldwide. Exposure can induce immediate behavioral and physiological changes in animals, sometimes leading to severe health consequences. Nevertheless, many organisms persist in light-polluted environments and may have mechanisms of habituating, reducing responses to repeated exposure over time, but this has yet to be tested experimentally. Here, we tested whether zebra finches (Taeniopygia guttata) can habituate to dim (0.3 lux) ALAN, measuring behavior, physiology (oxidative stress and telomere attrition), and gene expression in a repeated measures design, over 6 months. We present evidence of tolerance to chronic exposure, persistent behavioral responses lasting 8 weeks post-exposure, and attenuation of responses to re-exposure. Oxidative stress decreased under chronic ALAN. Changes in the blood transcriptome revealed unique responses to past exposure and re-exposure. Results demonstrate organismal resilience to chronic stressors and shed light on the capacity of birds to persist in an increasingly light-polluted world.

Postpartum Ovarian Vein Thrombosis: Case Report

INTRODUCTION

Postpartum ovarian vein thrombosis (POVT) is an uncommon diagnosis that may lead to morbidity or mortality if unrecognized.

CASE REPORT

This report discusses a single case of POVT in a community hospital, along with the treatment and clinical course.

CONCLUSION

The mechanism is believed to be right-sided clot formation provoked by anatomical and hormonal changes of gestation. Diagnosis is challenging as most patients are previously healthy and symptoms are often vague. Although the differential is broad, modern imaging is sensitive and specific for diagnosis. Prompt treatment with broad-spectrum antibiotics and anticoagulation may reduce morbidity, and prognosis following treatment is excellent.

The diversity of photosensitivity and its implications for light pollution

Artificial light at night (ALAN) is a pervasive anthropogenic pollutant, emanating from urban and suburban developments and reaching nearly all ecosystems from dense forests to coastlines. One proposed strategy for attenuating the consequences of ALAN is to modify its spectral composition to forms that are less disruptive for photosensory systems. However, ALAN is a complicated pollutant to manage due to the extensive variation in photosensory mechanisms and the diverse ways these mechanisms manifest in biological and ecological contexts. Here, we highlight the diversity in photosensitivity across taxa and the implications of this diversity in predicting biological responses to different forms of night lighting. We curated this paper to be broadly accessible and inform current decisions about the spectrum of electric lights used outdoors. We advocate that efforts to mitigate light pollution should consider the unique ways species perceive ALAN, as well as how diverse responses to ALAN scale up to produce diverse ecological outcomes.

Stress-responsiveness influences baseline glucocorticoid levels: Revisiting the under 3min sampling rule

Plasma glucocorticoid (CORT) levels collected within 3min of capture are commonly believed to reflect pre-stressor, baseline CORT levels. Differences in these "baseline" values are often interpreted as reflecting differences in health, or the amount of social and environmental stress recently experienced by an individual. When interpreting "baseline" values it is generally assumed that any effect of capture-and-handling during the initial sampling period is small enough and consistent enough among individuals to not obscure pre-capture differences in CORT levels. However, plasma CORT increases in less than 3min post-capture in many free-living, endothermic species in which timing has been assessed. In addition, the rate of CORT secretion and the maximum level attained (i.e., the degree of stress-responsiveness) during a severe stressor often differs among individuals of the same species. In Florida scrub-jays (Aphelocoma coerulescens), an individual's stress-responsiveness during a 30min post-capture stressor is correlated with CORT levels in samples collected within 1.5min of capture, suggesting there is an intrinsic connection between stress-responsiveness and pre-capture CORT levels. Although differences in stress-responsiveness accounted for just 11% of the variance in these samples, on average, higher stress-responsive jays (top third of individuals) had baseline values twice that of lower stress-responsive jays (bottom third). Further, plasma CORT levels begin to increase around 2min post-capture in this species, but the rate of increase between 2 and 3min differs markedly with CORT increasing more rapidly in jays with higher stress-responsiveness. Together, these data indicate that baseline CORT values can be influenced by an individual's stress response phenotype and the differences due to stress-responsiveness can be exaggerated during sample collection. In some cases, the effects of differences in stress-responsiveness and the increase in CORT during sample collection could obscure, or supersede, differences in pre-capture plasma CORT levels that are caused by extrinsic factors.

The ins and outs of the striatum: role in drug addiction

Addiction is a chronic relapsing disorder characterized by the loss of control over drug intake, high motivation to obtain the drug, and a persistent craving for the drug. Accumulating evidence implicates cellular and molecular alterations within cortico-basal ganglia-thalamic circuitry in the development and persistence of this disease. The striatum is a heterogeneous structure that sits at the interface of this circuit, receiving input from a variety of brain regions (e.g., prefrontal cortex, ventral tegmental area) to guide behavioral output, including motor planning, decision-making, motivation and reward. However, the vast interconnectivity of this circuit has made it difficult to isolate how individual projections and cellular subtypes within this circuit modulate each of the facets of addiction. Here, we review the use of new technologies, including optogenetics and DREADDs (Designer Receptors Exclusively Activated by Designer Drugs), in unraveling the role of the striatum in addiction. In particular, we focus on the role of striatal cell populations (i.e., direct and indirect pathway medium spiny neurons) and striatal dopaminergic and glutamatergic afferents in addiction-related plasticity and behaviors.

Robust behavioral effects of song playback in the absence of testosterone or corticosterone release

Some species of songbirds elevate testosterone in response to territorial intrusions while others do not. The search for a general explanation for this interspecific variation in hormonal response to social challenges has been impeded by methodological differences among studies. We asked whether song playback alone is sufficient to bring about elevation in testosterone or corticosterone in the dark-eyed junco (Junco hyemalis), a species that has previously demonstrated significant testosterone elevation in response to a simulated territorial intrusion when song was accompanied by a live decoy. We studied two populations of juncos that differ in length of breeding season (6-8 vs. 14-16 weeks), and conducted playbacks of high amplitude, long-range song. In one population, we also played low amplitude, short-range song, a highly potent elicitor of aggression in juncos and many songbirds. We observed strong aggressive responses to both types of song, but no detectable elevation of plasma testosterone or corticosterone in either population. We also measured rise in corticosterone in response to handling post-playback, and found full capacity to elevate corticosterone but no effect of song class (long-range or short-range) on elevation. Collectively, our data suggest that males can mount an aggressive response to playback without a change in testosterone or corticosterone, despite the ability to alter these hormones during other types of social interactions. We discuss the observed decoupling of circulating hormones and aggression in relation to mechanisms of behavior and the cues that may activate the HPA and HPG axes.

Dysarthria and dysphagia due to the opercular syndrome in multiple sclerosis

We report a patient with relapsing-remitting multiple sclerosis (RRMS), who developed bilateral severe tongue weakness due to the anterior opercular syndrome. This was caused by a recent inflammatory demyelinating lesion in the right perisylvian juxtacortical region, superimposed on a pre-existing left perisylvian lesion, which had previously caused temporary isolated right tongue weakness.

K-shell photodetachment of Li(-): experiment and theory

An experimental K-shell photodetachment study of Li(-) giving rise to doubly photoionized Li(+) ions has been carried out at the Advanced Light Source, using a collinear photon-ion beam apparatus. The experiment reveals dramatic structure, differing substantially both qualitatively and quantitatively from the corresponding processes above the 1s ionization threshold in Li and Li(+), as predicted by our enhanced R-matrix calculation. The experimental/theoretical comparison shows good agreement over some of the photon energy range, and also reveals some puzzling discrepancies.

Molecular cloning and characterization of a murine hemicholinium-3-sensitive choline transporter

In cholinergic neurons, a specific requirement for precursor choline in the biosynthesis of acetylcholine (ACh) is thought to be sustained by a presynaptic, hemicholinium-3 (HC-3)-sensitive choline transporter (CHT). This transporter exhibits micromolar affinity for choline and transport activity is Na(+)- and Cl(-)-dependent. Based on the sequence information available with the recent cloning of rat and human CHTs [Okuda, Haga, Kanai, Endou, Ishihara and Katsura (2000) Nat. Neurosci. 3, 120-125; Apparsundaram, Ferguson, George Jr and Blakely (2000) Biochem. Biophys. Res. Commun. 276, 862-867; Okuda and Haga (2000) FEBS Lett. 484, 92-97], we have identified a murine CHT orthologue (mCHT) by reverse transcriptase-PCR of spinal cord mRNA and confirmed this sequence using assembled mouse genomic DNA. Inferred splice junctions for mCHT exons are conserved with those of hCHT. The mCHT cDNA encodes a protein of 580 amino acids with 93% and 98% amino acid identity to human CHT and rat CHT1, respectively. Hydropathy analysis of the predicted amino acid sequence of mCHT indicates a protein containing 13 transmembrane domains (TMDs), with the N-terminus oriented extracellularly and the C-terminus oriented intracellularly. Northern blot analysis of mouse tissues reveals the expression of mCHT as a single transcript of approximately 5 kb with highest expression in regions that are rich in cholinergic cell bodies, e.g. the spinal cord, brainstem, mid-brain and striatum, whereas hybridization signals are absent in regions lacking cholinergic soma, e.g. the cerebellum and kidney. Expression of mCHT in COS-7 cells results in high-affinity [(3)H]HC-3-binding sites (K(d)=5 nM), and Na(+)- and Cl(-)-dependent HC-3-sensitive choline uptake (K(m)=2 microM), assessed in resealed membrane vesicles. The availability of cloned, functional mCHT and its cognate genomic DNA should prove useful for studies of mCHT regulation and should open possibilities for evaluation of CHT dysfunction in murine models.

Molecular cloning of a human, hemicholinium-3-sensitive choline transporter

Under many physiological circumstances, Na(+)- and Cl(-)-dependent, hemicholinium-3 (HC-3)-sensitive, high-affinity choline uptake (HACU) in cholinergic neurons is thought to be rate-limiting in the biosynthesis of acetylcholine (ACh). Based on sequence information provided by the Human Genome Project and the recently reported rat CHT1 (rCHT1), we cloned a human CHT cDNA from spinal cord. The hCHT cDNA encodes a protein of 580 amino acids having 93% identity to rCHT1 and 51% identity to the Caenorhabditis elegans homolog CHO-1, and is distantly related to members of the Na(+)-coupled glucose transporter (SGLT) gene family of Na(+)-coupled glucose (SGLT), nucleoside and iodide transporters. Northern blot analysis reveals the expression of a approximately 5 kb transcript in human brain regions rich in cholinergic neurons including the putamen, spinal cord, and medulla. Expression of hCHT cDNA in COS-7 cells results in saturable, Na(+)/Cl(-)-dependent choline uptake (K(m) = 1.2 microM) in membrane vesicles and [(3)H] HC-3 binding (K(d) = 4 nM) in membrane fractions, consistent with characteristics reported in mammalian cholinergic neurons. Using radiation hybrid mapping techniques, we localized the hCHT gene to human chromosome 2q12. These studies elucidate the primary structure and chromosomal localization of hCHT and provide a basis for mechanistic analysis of HACU regulation and an investigation of the role of hCHT in disease states.

Antidepressant-like effects of the subtype-selective nicotinic acetylcholine receptor agonist, SIB-1508Y, in the learned helplessness rat model of depression

RATIONALE

Epidemiological studies of smokers suggest that there is a link between nicotine and depression. Nonetheless, few studies have examined the potential use of nicotinic ligands in the treatment of depression.

OBJECTIVES

The goal of this study was to evaluate the effects of SIB-1508Y, a novel subtype-selective ligand for high affinity nicotinic acetylcholine receptors (nAChRs), in the learned helplessness model of depression in rats.

METHODS

In this model, exposure to inescapable foot-shock produces a lasting deficit in escape responses emitted in a subsequent conditioned avoidance procedure (learned helplessness). The effect of SIB-1508Y on learned helplessness was compared to the clinically used antidepressants, imipramine and fluoxetine, and the non-selective nAChR ligand, nicotine.

RESULTS

Similarly to imipramine and fluoxetine, subchronic treatment (5 days) with SIB-1508Y reversed the escape deficit in the learned helplessness model in a dose dependent manner. The effect of SIB-1508Y on learned helplessness was still apparent 1 week following drug administration and was also maintained after 4 weeks of daily administration. In contrast, while nicotine was able to attenuate the learned helplessness deficit, this trend only reached statistical significance after chronic administration. The non-competitive ion channel blocker mecamylamine increased escape failures when administered alone and blocked the effects of SIB-1508Y but not imipramine. SIB- 1508Y also produced an increase in avoidance responding, which suggests an enhancement of learning.

CONCLUSION

These results not only suggest a role for nAChRs in the development of a depressive-like syndrome, but also that subtype-selective nAChR agonists, such as SIB-1508Y, may offer a novel therapeutic approach to the treatment of depression.

Knowledge, attitudes, and behaviors of Alabama's primary care physicians regarding cancer genetics

PURPOSE

To determine Alabama's primary care physicians' knowledge, attitudes, and behaviors regarding cancer genetics.

METHOD

A questionnaire was mailed to a random sample of 1,148 physicians: family and general practitioners, internists, and obstetrician-gynecologists.

RESULTS

Of the surveyed physicians, 22.1% responded. Of the respondents, 63% to 85% obtained family histories of cancer from 76% to 100% of their patients. Obstetrician-gynecologists referred more patients for cancer genetic testing (p = .008) and were more confident in their abilities to tailor preventive recommendations based on the results (p = .05) than were the other physicians. Primary care physicians were more likely than were obstetrician-gynecologists to identify lack of time during the patient visit as hindering efforts to do genetic counseling (p = .01). Physicians in practice for ten years or less were more confident in explaining genetic test results than were those in practice for more than 20 years (p = .01).

CONCLUSION

These data validate gaps in primary care practices in obtaining family history of cancer, as well as lack of confidence in explaining genetic test results and in tailoring recommendations based on the tests.

Purification and reconstitution of an osmosensor: transporter ProP of Escherichia coli senses and responds to osmotic shifts

The ProP protein of Escherichia coli is an osmoregulatory H+-compatible solute cotransporter. ProP is activated by an osmotic upshift in both whole cells and membrane vesicles. We are using biochemical and biophysical techniques to explore the osmosensory and catalytic mechanisms of ProP. We now report the purification and reconstitution of the active transporter. Protein purification was facilitated by the addition of six histidine (His) codons to the 3' end of proP. The recombinant gene was overexpressed from the E. coli galP promoter, and ProP-(His)6 was shown to be functionally equivalent to wild-type ProP by enzymatic assay of whole cells. ProP-(His)6, purified by Ni2+ (NTA) affinity chromatography, cross-reacted with antibodies raised against the ProP protein. ProP-(His)6 was reconstituted into Triton X-100 destabilized liposomes prepared with E. coli phospholipid. The reconstituted transporter mediated proline accumulation only if (1) a membrane potential was generated by valinomycin-mediated K+ efflux and (2) the proteoliposomes were subjected to an osmotic upshift (0.6 M sucrose). Activity was also stimulated by DeltapH. Pure ProP acts, in the proteoliposome environment, as sensor, transducer, and respondent to a hyperosmotic shift. It is the first such osmosensor to be isolated.

Mast cell cholangiopathy: another cause of sclerosing cholangitis

A 75-year-old woman with known systemic mastocytosis presented with abdominal pain, ascites, and bile duct thickening on computed tomography and ultrasonography. A liver biopsy specimen showed infiltration with mast cells. Endoscopic retrograde cholangiography showed ductal changes compatible with those found in primary sclerosing cholangitis. Brush cytology of the intrahepatic bile ducts confirmed mast cell infiltration. Systemic mastocytosis can infiltrate the biliary system, producing a cholangiopathy radiographically similar to primary sclerosing cholangitis.

Fiber-optic interferometric sensor for the detection of acoustic emission within composite materials

An optical-fiber Michelson interferometric acoustic emission sensor is described. The sensor uses ordinary singlemode fiber and is embedded in the composite material under test. Signals are demodulated through the active homodyne. This system provides a novel approach for material nondestructive evaluation.

Use of hexadeuterated valproic acid and gas chromatography-mass spectrometry to determine the pharmacokinetics of valproic acid

Di-[( 3,3,3-2H3]propyl)acetic acid, a hexadeuterated analogue of valproic acid, was synthesized and its pharmacokinetic properties compared with valproic acid. Concentrations of valproic acid and [2H]valproic acid in serum and saliva were determined by GC-MS using selected-ion monitoring. Saliva drug levels were measured with good precision down to 0.1 microgram/mL. Kinetic equivalence of valproic acid and [2H]valproic acid was demonstrated in a single-dose study in a human volunteer. An isotope effect was observed for omega-oxidation, but the difference in metabolism was not sufficient to make [2H]valproic acid biologically nonequivalent. The application of [2H]valproic acid to determine the kinetics of valproic acid under steady-state concentrations was evaluated in the same volunteer. The kinetic data obtained with [2H]valproic acid was consistent with previously reported values for valproic acid including kinetic differences observed between single-dose and steady-state experiments. Saliva levels of valproic acid were found to give a good correlation (r = 0.953) with total serum valproic acid under multiple-dose conditions. A concentration dependence was found for the ratio of saliva valproic acid to free valproic acid in serum, low ratios being observed at high serum concentrations of valproic acid.

Outcomes and indications of corpus callosum section for intractable seizure control

Callosotomy (CCS) was performed in 9 cases of rigorously classified drug-refractory epilepsy not eligible for focal cortical resection. Complete CCS was carried out in two stages in 8 patients. 1 case had an anterior CCS only. None of the 9 patients has become seizure free. In 7, seizure frequency has diminished by a factor of 3-60 for at least one seizure type. Drop attacks in 2 cases have ceased. Clinical seizure patterns appeared more helpful in predicting outcome than preoperative EEG and stereoelectroencephalographic studies. Complete CCS may result in prolonged behavioral disturbances in the areas of language, hemisphere competition and attention-memory sequencing with impact on the sphere of daily living.