The estimation of food consumption in larval and juvenile fish: experimental evaluation of bioenergetics models

The two most commonly used methods for estimating the food consumption of fish are based on either the evacuation rate of food or the energy budget of an individual fish. In this study, both of those methods were used to estimate the food consumption of fish under experimental conditions. Bioenergetics models of vendace Coregonus albula , smelt Osmerus eperlanus , roach Rutilus rutilus and perch Perca fluviatilis were reconstructed based on experimental data and published values. The precision of the bioenergetics estimates for food consumption was evaluated under experimental conditions. The modelling efficiency (EF) of the bioenergetics model was 0.90, 0.97 and 0.93 for coregonids, roach and perch, respectively, which indicated good agreement between observed and predicted values. Under our experimental conditions, the bioenergetics model estimated food consumption better than the evacuation rate model.     

Left ventricular mass, geometry, and filling in endurance athletes: association with exercise blood pressure

Karjalainen, Jouko, Matti Mäntysaari, MattiViitasalo, and Urho Kujala. Left ventricular mass, geometry,and filling in endurance athletes: association with exercise bloodpressure. J. Appl. Physiol. 82(2):531-537, 1997.We studied whether left ventricular (LV) mass andconcentricity [relative myocardial volume (RMV)] areassociated with exercise blood pressure (BP) in athletes. LV structureand filling were evaluated by Doppler echocardiography and BP inmaximal bicycle ergometry and isometric handgrip tests on 32 maleendurance athletes and 15 age-matched controls. Indexed LV mass was 145 ± 14 (SD) g/m in athletes and 93 ± 20 g/m incontrols. Mass was not associated with BP at rest or inlow-grade exercise, but with heavier exercise loads this associationstrengthened in athletes, being maximal at peak exercise(r = 0.65 for mass and 0.58 forindexed mass; P < 0.001). Multivariate analysis indicated that BP at peakexercise accounted for 34% and the amount of training for anadditional 11% of the variance in indexed LV mass. RMV was 21% largerin athletes. Only the increase in systolic BP during handgrip explainedsignificantly (19%) the variance in RMV. LV filling velocities werenot associated with mass, RMV, or BP. We conclude that in enduranceathletes LV mass is associated with BP in heavy dynamic exercise and LVconcentricity with BP response in static exercise.

     

Genetic Relatedness Among Strains of Heterobasidion annosum as Detected by Random Amplified Polymorphic DNA Markers

Heterobasidion annosum, the casual agent of root and butt rots of trees is one of the most important plant pathogens in temperate coniferous regions of the world. It is comprised of several intersterility groups with different host preferences. Of the H. annosum isolates from various geographical regions belonging to various intersterility groups, 36 showed group-specific banding patterns in RAPD assay. More polymorphisms were found within the S- and F-group isolates than in the P group. Genetic similarities among the isolates were determined by UPGMA clustering revealing the presence of four major clusters: P, S, F, and the North American S. The P group was the most distinctive of all the other groups, while the European S and F and the North American S were more closely related. The P group showed only 20% similarity to the other groups and may be referred to as a subspecies. The North American S group was separate from the European S group. The potential influence of the historical spread of coniferous trees in the isolate genetic differentiation in Europe is discussed.     

Intensity of nest defence is not related to degree of paternity in the willow tit Parus montanus

We asked whether willow tit Parus montanus males adjust their parental care according to their paternity in current brood. The origin of the nestlings was determined by using molecular technique, and the studied broods were assigned into extra-pair paternity (EPP) broods, if at least one nestling was fathered by another male, and truly monogamous broods. Over 3  years, 14 of 40  broods (35%) included EP-offspring, and 29 of 273  nestlings (11%) were EP-young. Intensity of parental care was measured with risk-taking against a potential predator, mounted stoat Mustela erminea . The results showed that risk-taking by EPP males did not differ from that by monogamous males. Neither was the sexual difference in risk-taking different at EPP and monogamous broods. Our results are consistent with the hypothesis that males do not adjust their level of care to paternity, perhaps because they have no reliable cues for assessing their paternity. This may be related to the success of mate-guarding in their breeding environment, closed forests. Guarding is seemingly successful as the EPP levels are rather low, but it is not totally sure making the potential costs, rejection of own young, too high. We also discuss other population characteristics which may further prevent the evolution of paternity assessment in northern willow tits.     

Daily impact score in long-term acceleration measurements of exercise

Mechanical loading increases and maintains bone mass and strength. Daily stress stimulus and osteogenic index theories have been suggested to describe the osteogenic potential of exercise, using exponential or logarithmic relationships, respectively, between loading numbers and magnitude. Inspired by these theories, the aim of this study was to develop and test a daily impact score (DIS) using long-term continuous acceleration measurements of exercise.Acceleration data were collected during a previous exercise trial, in which the subjects (healthy women, 35–40 years, N=34 in the high-impact exercise group and N=30 in the control group) wore a body movement monitor on their waist during the 12-month study. DIS was calculated from the 12-month average daily acceleration distributions in two ways: DIS_Exp adopted from the daily stress stimulus and DIS_Log simplified from the osteogenic index. Areal bone mineral density (aBMD) at the proximal femur and cortical bone geometry at the mid-femur were measured at baseline and 12 months.DIS calculated in either of the ways was significantly higher in the exercise group than in the control group. DIS_Exp and DIS_Log were strongly correlated (R=0.982). Both DIS_Exp and DIS_Log were significantly associated with 12-month aBMD changes at the hip (R up to 0.550, p<0.01) and geometry changes at the mid-femur (R up to 0.472, p<0.05) in the exercise group.DIS calculated either from exponential or logarithmic relationship can be used in acceleration-based measurements of daily exercise. DIS was positively related with changes in hip aBMD and mid-femur bone geometry after 12 months of exercise.     

Glutamine synthetase and glucose-6-phosphate isomerase are adhesive moonlighting proteins of Lactobacillus crispatus released by epithelial cathelicidin LL-37

Glutamine synthetase (GS) and glucose-6-phosphate isomerase (GPI) were identified as novel adhesive moonlighting proteins of Lactobacillus crispatus ST1. Both proteins were bound onto the bacterial surface at acidic pHs, whereas a suspension of the cells to pH 8 caused their release into the buffer, a pattern previously observed with surface-bound enolase and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) of L. crispatus. The pH shift was associated with a rapid and transient increase in cell wall permeability, as measured by cell staining with propidium iodide. A gradual increase in the release of the four moonlighting proteins was also observed after the treatment of L. crispatus ST1 cells with increasing concentrations of the antimicrobial cationic peptide LL-37, which kills bacteria by disturbing membrane integrity and was here observed to increase the cell wall permeability of L. crispatus ST1. At pH 4, the fusion proteins His(6)-GS, His(6)-GPI, His(6)-enolase, and His(6)-GAPDH showed localized binding to cell division septa and poles of L. crispatus ST1 cells, whereas no binding to Lactobacillus rhamnosus GG was detected. Strain ST1 showed a pH-dependent adherence to the basement membrane preparation Matrigel. Purified His(6)-GS and His(6)-GPI proteins bound to type I collagen, and His(6)-GS also bound to laminin, and their level of binding was higher at pH 5.5 than at pH 6.5. His(6)-GS also expressed a plasminogen receptor function. The results show the strain-dependent surface association of moonlighting proteins in lactobacilli and that these proteins are released from the L. crispatus surface after cell trauma, under conditions of alkaline stress, or in the presence of the antimicrobial peptide LL-37 produced by human cells.     

The shift in plant species composition in a subarctic mountain birch forest floor due to climate change would modify the biogenic volatile organic compound emission profile

Background and aims

Mountain birch forests dominate in the Subarctic but little is known of their non-methane biogenic volatile organic compound (BVOC) emissions. The dwarf shrubs Empetrum hermaphroditum, Vaccinium myrtillus and Vaccinium uliginosum co-dominate in the forest floors of these forests. The abundance of these three dwarf shrubs relative to each other could be affected by climate warming expected to increase nutrient availability by accelerating litter decomposition and nutrient mineralization. We 1) compared the BVOC emission profiles of vegetation covers dominated by E. hermaphroditum and V. myrtillus plus V. uliginosum in a subarctic mountain birch forest floor, 2) distinguished the BVOCs emitted from plants and soil and 3) measured how the BVOC emissions from the different vegetation covers differed under darkness.

Methods

BVOCs were sampled during two growing seasons using a conventional ecosystem chamber-based method, collected on adsorbent and analyzed with gas chromatography–mass spectrometry.

Results

High abundance of E. hermaphroditum increased the sesquiterpene emissions. Soil released fewer different BVOCs than controls (i.e. natural vegetation) but the total emission rates were similar. Darkness did not affect the emissions. Carbon emitted as BVOCs was less than 0.2% of the CO₂ exchange.

Conclusions

Our results suggest that sesquiterpene emissions from subarctic mountain birch forest floors would be reduced following an increased abundance of V. myrtillus and V. uliginosum with climate change because these species respond rapidly to increased nutrient availability.