Soybean Cyst Nematodes Influence Aboveground Plant Volatile Signals Prior to Symptom Development

Soybean cyst nematode (SCN), Heterodera glycines, is one of the most destructive soybean pests worldwide. Unlike many diseases, SCN doesn't show above ground evidence of disease until several weeks after infestation. Knowledge of Volatile Organic Compounds (VOCs) related to pests and pathogens of foliar tissue is extensive, however, information related to above ground VOCs in response to root damage is lacking. In temporal studies, gas chromatography-mass spectrometry analysis of VOCs from the foliar tissues of SCN infested plants yielded 107 VOCs, referred to as Common Plant Volatiles (CPVs), 33 with confirmed identities. Plants showed no significant stunting until 10 days after infestation. Total CPVs increased over time and were significantly higher from SCN infested plants compared to mock infested plants post 7 days after infestation (DAI). Hierarchical clustering analysis of expression ratios (SCN: Mock) across all time points revealed 5 groups, with the largest group containing VOCs elevated in response to SCN infestation. Linear projection of Principal Component Analysis clearly separated SCN infested from mock infested plants at time points 5, 7, 10 and 14 DAI. Elevated Styrene (CPV11), D-Limonene (CPV32), Tetradecane (CPV65), 2,6-Di-T-butyl-4-methylene-2,5-cyclohexadiene-1-one (CPV74), Butylated Hydroxytoluene (CPV76) and suppressed Ethylhexyl benzoate (CPV87) levels, were associated with SCN infestation prior to stunting. Our findings demonstrate that SCN infestation elevates the release of certain VOCs from foliage and that some are evident prior to symptom development. VOCs associated with SCN infestations prior to symptom development may be valuable for innovative diagnostic approaches.

Application of an improved proteomics method for abundant protein cleanup: molecular and genomic mechanisms study in plant defense

High abundance proteins like ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) impose a consistent challenge for the whole proteome characterization using shot-gun proteomics. To address this challenge, we developed and evaluated Polyethyleneimine Assisted Rubisco Cleanup (PARC) as a new method by combining both abundant protein removal and fractionation. The new approach was applied to a plant insect interaction study to validate the platform and investigate mechanisms for plant defense against herbivorous insects. Our results indicated that PARC can effectively remove Rubisco, improve the protein identification, and discover almost three times more differentially regulated proteins. The significantly enhanced shot-gun proteomics performance was translated into in-depth proteomic and molecular mechanisms for plant insect interaction, where carbon re-distribution was used to play an essential role. Moreover, the transcriptomic validation also confirmed the reliability of PARC analysis. Finally, functional studies were carried out for two differentially regulated genes as revealed by PARC analysis. Insect resistance was induced by over-expressing either jacalin-like or cupin-like genes in rice. The results further highlighted that PARC can serve as an effective strategy for proteomics analysis and gene discovery.

Relationship between physiological loss, performance decrement, and age in master athletes

BACKGROUND

The use of master athletes to describe an idealized rate of physiological loss associated with aging is quite common. The results of such studies suggest that older athletes may be able to reduce the rate of decline in functional loss. The findings of such studies have been questioned due to their limited sample size and the age range and gender of their subjects.

METHODS

We examined a group of 146 male and 82 female master athletes over the age of 40 years. Physiological parameters included maximal oxygen uptake (VO2max), body composition, muscle strength, bone density, and blood chemistries. Medical histories and training records were obtained via questionnaire.

RESULTS

Results demonstrated gender differences in body composition, blood chemistries, blood pressure, VO2max, muscle strength, bone density, and performance (p <.05). All metabolic parameters for men and most for women demonstrated significant losses across the age range (p <.05). In addition, strength and performance for men and women and bone density for women declined significantly with age (p <.05). The demonstrated loss rates did not differ by gender.

CONCLUSIONS

Although limited by the lack of a sedentary comparison group, these data suggest that age-related losses in VO2max may not be different from data previously reported for older sedentary adults and that loss in muscle strength and performance with aging is not linear.

Maximal aerobic power, lactate threshold, and running performance in master athletes

PURPOSE

This study sought to determine how lactate threshold (LT) is related to running performance in older male and female runners, if LT changes significantly with age, and if gender alters the relationship between LT and performance in older runners.

METHODS

Subjects were 168 master runners (111 men, 57 women) selected from a longitudinal study, who ran at least 10 miles x wk(-1) for 5 yr or more. VO2max was measured on a treadmill and body composition by hydrostatic weighing. Blood samples taken each minute of exercise were analyzed for lactate concentration and LT determined as the breakpoint in lactate accumulation. Performance times and training histories were self-reported by questionnaire.

RESULTS

Men had significantly greater body mass, fat-free mass (FFM), and VO2max (L x min(-1); mL x kg(-1) x min(-1)) than women. FFM and VO2max (L x min(-1); mL x kg(-1) x min(-1)) declined with age in both men and women. Running performance was significantly different between men and women and declined with age in both. LT (L x min(-1); mL x kg(-1) x min(-1)) was significantly different between men and women, and declined significantly with age in men, whereas LT (%VO2max) did not differ between men and women and increased significantly with age in both. VO2max (mL x kg(-1) x min(-1)) was the most significant predictor of performance in both men and women, whereas LT (L x min(-1)) added to the prediction of 5-km and 10-km performance in women.

CONCLUSION

The results of this study demonstrate that VO2max (mL x kg(-1) x min(-1)) is a better predictor of performance than LT in older male and female runners. Additionally, LT as a percentage of VO2max increases significantly with age.

The inability of hormone replacement therapy or chronic running to maintain bone mass in master athletes

BACKGROUND

Previous studies have demonstrated equivocal findings on the effect of chronic running on bone mass in post-menopausal women. The purpose of this study was to determine the effect of chronic running alone and in conjunction with hormone replacement therapy (HRT) on bone mineral density (BMD) in postmenopausal women.

METHODS

Forty-three women [15 premenopausal 48.1 +/- .4 yrs (Pre); 13 postmenopausal 57.3 +/- 2.3 yrs (Post); and 15 HRT-treated postmenopausal 56.8 +/- 1.5 yrs (PostE)] served as subjects. All were chronic runners (duration > 5 yrs, > 10 miles per week). BMD was determined by dual energy x-ray absorptiometry, VO2 max on a treadmill, body composition by hydrostatic weighing, knee strength by KinCom dynamometer, and training and menstrual history by questionnaire. Analysis of covariance with Tukey post hoc tests was utilized to compare the groups.

RESULTS

The groups were similar in body weight, VO2 max, years training, and miles run per week. Pre and PostE did not differ in total or spine BMD. However, Pre had greater hip BMD than PostE (.973 +/- .03 vs .876 +/- .03 g/cm2; p < .05). As well, Pre had greater BMD of the hip (.973 +/- .03 vs .805 +/- .03 g/cm2; p < .05), spine (1.047 +/- .04 vs .870 +/- .04 g/cm2; p < .05), and total body (1.115 +/- .02 vs .996 +/- .03 g/cm2; p < .05) than Post.

CONCLUSIONS

These results suggest that (a) chronic running + HRT is insufficient to protect hip BMD and (b) chronic running alone provides no protection for bone mass in postmenopausal women.

A comparison of cardiopulmonary adaptations to exercise in pregnancy at sea level and altitude

OBJECTIVE

The purpose of this study was to compare maternal cardiopulmonary and fetal responses of lowlander pregnant women in the third trimester to exercise at sea level and at an altitude of 6000 feet.

STUDY DESIGN

Seven women at 33.86 +/- 1 weeks' gestation performed a symptom-limited maximal exercise test and a submaximal cardiac output exercise test at sea level at an altitude of 6000 feet. Cardiopulmonary and metabolic variables were measured and compared at sea level and altitude.

RESULTS

Maximal oxygen consumption and work levels were limited by short-term altitude exposure. Ventilatory variables were not significantly influenced by altitude exposure. During submaximal exercise no alteration in exercise efficiency or response was seen for most of the variables when altitude and sea level data were compared. Both cardiac output and stroke volume were elevated at altitude at rest but not during exercise, suggesting a lower reserve for both variables at altitude. Level of plasma glucose, lactate, norepinephrine, and epinephrine were not significantly influenced by altitude exposure. Fetal heart rate responses did not differ between the sea level and altitude conditions.

CONDITIONS

Lowlander pregnant women in the third trimester have some limitations to maximal aerobic capacity but not submaximal exercise on short-term altitude exposure. No ominous fetal responses have been observed during this study. The results suggest that pregnant women may engage in at least brief moderate exercise bouts at moderate altitude without adverse consequences.

Exercise as a treatment modality to maintain normoglycemia in gestational diabetes

Exercise can be a safe alternative to insulin therapy and may possibly eliminate the need for insulin in GDM. Exercise therapy should be explored as an additional means to maintain normoglycemia, preconceptionally as well as throughout pregnancy.