A powdery mildew infection on a shared host plant affects the dynamics of the Glanville fritillary butterfly populations

While biotrophic fungal pathogens have generally been considered to have negative effects on phytophagous insects sharing the same host plant, very little is known about whether fungal infection may affect the dynamics of natural insect populations. This study was designed to determine the effects of fungal infection by Podosphaera plantaginis , a powdery mildew, of a shared host plant, Plantago lanceolata , on the larvae of the butterfly Melitaea cinxia . Larval responses were assessed in a no-choice feeding assay involving infected and healthy leaves, as well as in a behavioural experiment in which larvae had an opportunity to move among infected and uninfected plants. In the no-choice feeding assay larvae developed more slowly and weighed less at diapause when feeding on fungal-infected than on healthy leaves. In the behavioural experiment larval groups tended to leave the original host plant when it was infected by P. plantaginis . This tendency was associated with splitting of larval groups into smaller subgroups. These effects observed in an experimental setting were also confirmed to act under natural conditions. An analysis of 167 M. cinxia populations showed that over-winter survival of larval groups was 26% lower in host populations infected by the mildew than in non-infected host populations. Smaller, more slowly developing larvae may not be ready to enter diapause at the onset of fall, causing the observed increase in mortality. This is the first study to demonstrate that the negative effects of a biotrophic fungal infection may extend to the dynamics of entire insect populations.     

Incident Hip Fractures among Community Dwelling Persons with Alzheimer’s Disease in a Finnish Nationwide Register-Based Cohort

Background

Previous cohort studies have shown that persons with Alzheimer’s disease (AD) have a higher risk of hip fractures but recent data from large representative cohorts is scarce.

Methods

We investigated the association between AD and prevalent and incident hip fractures in an exposure-matched cohort study conducted in Finland 2002–2009 (the Medication and Alzheimer’s disease in 2005 study; MEDALZ-2005). The study population included all community-dwelling persons with verified AD diagnosis in Finland on December 31, 2005 and one matched comparison person per AD case (N = 56,186, mean age 79.9 (SD 6.8) years, range 42–101 years). The diagnosis of AD was extracted from a special reimbursement register. Data on hip fractures during 2002–2009 was extracted from the Finnish National hospital discharge register. Analyses of incident hip fractures (n = 2,861) were restricted to years 2006–2009.

Results

Persons with AD were twice as likely to have previous hip fracture in 2005 (odds ratio, 95% confidence interval 2.00, 1.82–2.20) than matched aged population without AD. They were also more likely to experience incident hip fracture during the four-year follow-up (hazard ratio, 95% confidence interval 2.57, 2.32–2.84, adjusted for health status, psychotropic drug and bisphosphonate use). The AD-associated risk increase decreased linearly across age groups. Although people with AD had higher risk of hip fractures regardless of sex, the risk increase was larger in men than women.

Conclusion

Findings from our nationwide study are in line with previous studies showing that persons with AD, regardless of sex or age, have higher risk of hip fracture in comparison to general population. Although there was some suggestion of effect modification by age or sex, AD was consistently associated with doubling of the risk of incident hip fracture.     

Influence of selenium (Se) on carbohydrate metabolism, nodulation and growth in alfalfa (Medicago sativa L.)

Background and aims

Extensive worldwide dryland degradation calls for identification of functional traits critical to dryland plant performance and restoration outcomes. Most trait examination has focused on drought tolerance, although most dryland systems are water and nutrient co-limited. We studied how drought impacts both plant water relations and nitrogen (N) nutrition.

Methods

We grew a suite of grasses common to the Intermountain West under both well-watered and drought conditions in the greenhouse. These grasses represented three congener pairs (Agropyron, Elymus, Festuca) differing in their habitat of origin (“wetter” or “drier”). We measured growth, water relations, N resorption efficiency and proficiency and photosynthetic N use efficiency in response to drought.

Results

Drought decreased growth and physiological function in the suite of grasses studied, including a negative impact on plant N resorption efficiency and proficiency. This effect on resorption increased over the course of the growing season. Evolutionary history constrained species responses to treatment, with genera varying in the magnitude of their response to drought conditions. Surprisingly, habitat of origin influenced few trait responses.

Conclusions

Drought impacted plant N conservation, although these responses also were constrained by evolutionary history. Future plant development programs should consider drought tolerance not only from the perspective of water relations but also plant mineral nutrition, taking into account the role of phylogeny.     

Mitochondrial Dysfunction in the Pathogenesis of Necrotic and Apoptotic Cell Death

Mitochondria are frequently the target of injury after stresses leading to necrotic and apoptoticcell death. Inhibition of oxidative phosphorylation progresses to uncoupling when opening ofa high conductance permeability transition (PT) pore in the mitochondrial inner membraneabruptly increases the permeability of the mitochondrial inner membrane to solutes of molecularmass up to 1500 Da. Cyclosporin A (CsA) blocks this mitochondrial permeability transition(MPT) and prevents necrotic cell death from oxidative stress, Ca²⁺ ionophore toxicity,Reye-related drug toxicity, pH-dependent ischemia/reperfusion injury, and other models of cell injury.Confocal fluorescence microscopy directly visualizes onset of the MPT from the movementof green-fluorescing calcein into mitochondria and the simultaneous release from mitochondriaof red-fluorescing tetramethylrhodamine methylester, a membrane potential-indicatingfluorophore. In oxidative stress to hepatocytes induced by tert-butylhydroperoxide, NAD(P)Hoxidation, increased mitochondrial Ca²⁺, and mitochondrial generation of reactive oxygen speciesprecede and contribute to onset of the MPT. Confocal microscopy also shows directly thatthe MPT is a critical event in apoptosis of hepatocytes induced by tumor necrosis factor-.Progression to necrotic and apoptotic cell killing depends, at least in part, on the effect theMPT has on cellular ATP levels. If ATP levels fall profoundly, necrotic killing ensues. If ATPlevels are at least partially maintained, apoptosis follows the MPT. Cellular features of bothapoptosis and necrosis frequently occur together after death signals and toxic stresses. A newterm, necrapoptosis, describes such death processes that begin with a common stress or deathsignal, progress by shared pathways, but culminate in either cell lysis (necrosis) or programmedcellular resorption (apoptosis) depending on modifying factors such as ATP.     

Mitochondria,nitric oxide,and cardiovascular dysfunction

Cardiovascular diseases encompass a wide spectrum of abnormalities with diverse etiologies. The molecular mechanisms underlying these disorders include a variety of responses such as changes in nitric oxide- (NO) dependent cell signaling and increased apoptosis. An interesting aspect that has received little or no attention is the role mitochondria may play in the vascular changes that occur in both atherosclerosis and hypertension. With the changing perspective of the organelle from simply a role in metabolism to a contributor to signal transduction pathways, the role of mitochondria in cells with relatively low energy demands such as the endothelium has become important to understand. In this context, the definition of the NO-cytochrome c oxidase signaling pathway and the influence this has on cytochrome c release is particularly important in understanding apoptotic mechanisms involving the mitochondrion. This review examines the role of compromised mitochondrial function in a variety of vascular pathologies and the modulation of these effects by NO. The interaction of NO with the various mitochondrial respiratory complexes and the role NO plays in modulating mitochondrial-mediated apoptosis in these systems will be discussed.     

Validation of the Hsp150 polypeptide carrier and HSP150 promoter in expression of rat alpha2,3-sialyltransferase in yeasts

Heterologous glycoproteins usually do not fold properly in yeast cells and fail to leave the endoplasmic reticulum. Here we show that the Hsp150Delta polypeptide carrier promoted proper folding and secretion of the catalytic ectodomain of rat alpha2,3-sialyltransferase (ST3Ne) in Pichia pastoris. The efficiency of the Hsp150Delta carrier in P. pastoris and Saccharomyces cerevisiae was at least as high as that of the MFalpha carrier. Most of Hsp150Delta-ST3Ne and MFalpha-ST3Ne remained noncovalently attached to the cell wall via the ST3Ne portion. The strength of the HSP150 promoter was found to be comparable to that of the GAL1 promoter.     

Age and gender dependency of baroreflex sensitivity in healthy subjects

Laitinen, Tomi, Juha Hartikainen, Esko Vanninen, LeoNiskanen, Ghislaine Geelen, and Esko Länsimies. Age andgender dependency of baroreflex sensitivity in healthy subjects.J. Appl. Physiol. 84(2): 576-583, 1998.We evaluated the correlates of baroreflex sensitivity (BRS) inhealthy subjects. The study consisted of 117 healthy, normal-weight,nonsmoking male and female subjects aged 23-77 yr. Baroreflexcontrol of heart rate was measured by using the phenylephrinebolus-injection technique. Frequency- and time-domain analysis of heartrate variability and an exercise test were performed. Plasmanorepinephrine, epinephrine, insulin, and arginine vasopressinconcentrations and plasma renin activity were measured. In theunivariate analysis, BRS correlated with age(r = 0.65,P < 0.001), diastolic blood pressure(r = 0.47, P < 0.001), exercise capacity(r = 0.60, P < 0.001), and the high-frequency component of heart rate variability (r = 0.64, P < 0.001). There was also asignificant correlation between BRS and plasma norepinephrine concentration (r = 0.22,P < 0.05) and plasma renin activity (r = 0.32, P < 0.001). According to themultivariate analysis, age and gender were the most importantphysiological correlates of BRS. They accounted for 52% ofinterindividual BRS variation. In addition, diastolic blood pressureand high-frequency component of heart rate variability were significantindependent correlates of BRS. BRS was significantly higher in men thanin women (15.0 ± 1.2 vs. 10.2 ± 1.1 ms/mmHg, respectively;P < 0.01). Twenty-four percent ofwomen >40 yr old and 18% of men >60 yr old had markedly depressedBRS (<3 ms/mmHg). We conclude that physiological factors, particularly age and gender, have significant impact on BRS in healthysubjects. In addition, we demonstrate that BRS values that have beenproposed to be useful in identifying postinfarction patients at highrisk of sudden death are frequently found in healthy subjects.

     

Infant Growth after Preterm Birth and Mental Health in Young Adulthood

Objectives

Faster growth after preterm birth benefits long-term cognitive functioning. Whether these benefits extend to mental health remains largely unknown. We examined if faster growth in infancy is associated with better self-reported mental health in young adults born preterm at very low birth weight (VLBW) (<1500g).

Study Design

As young adults, participants of the Helsinki Study of Very Low Birth Weight Adults self-reported symptoms of depression and attention deficit/hyperactivity disorder (ADHD) (n = 157) and other psychiatric problems (n = 104). As main predictors of mental health outcomes in linear regression models, we used infant weight, length, and head circumference at birth, term, and 12 months of corrected age, and growth between these time points. Growth data were collected from records and measures at term and at 12 months of corrected age were interpolated. Additionally, we examined the moderating effects of intrauterine growth restriction.

Results

Size at birth, term, or 12 months of corrected age, or growth between these time points were not associated with mental health outcomes (p-values >0.05). Intrauterine growth restriction did not systematically moderate any associations.

Conclusions

Despite the high variability in early growth of VLBW infants, the previously described association between slow growth in infancy and poorer cognitive functioning in later life is not reflected in symptoms of depression, ADHD, and other psychiatric problems. This suggests that the development of cognitive and psychiatric problems may have dissimilar critical periods in VLBW infants.