Unisexual flower initiation in the monoecious Quercus suber L.: a molecular approach

Several plant species display a temporal separation of the male and female flower organ development to enhance outbreeding; however, little is known regarding the genetic mechanisms controlling this temporal separation. Quercus suber is a monoecious oak tree with accentuated protandry: in late winter, unisexual male flowers emerge adjacent to the swollen buds, whereas unisexual female flowers emerge in the axils of newly formed leaves formed during spring (4-8 weeks after male flowering). Here, a phylogenetic profiling has led to the identification of cork oak homologs of key floral regulatory genes. The role of these cork oak homologs during flower development was identified with functional studies in Arabidopsis thaliana. The expression profile throughout the year of flower regulators (inducers and repressors), in leaves and buds, suggests that the development of male and female flowers may be preceded by separated induction events. Female flowers are most likely induced during the vegetative flush occurring in spring, whereas male flowers may be induced in early summer. Male flowers stay enclosed within the pre-dormant buds, but complete their development before the vegetative flush of the following year, displaying a long period of anthesis that spans the dormant period. Our results portray a genetic mechanism that may explain similar reproductive habits in other monoecious tree species.

The relationship between aerosol concentration and atmospheric potential gradient in urban environments

Urban aerosol is a growing concern for people living within cities; aerosol have been implicated in many ill health conditions, including that of the lung and of the heart. Atmospheric potential gradient is a consequence of charge carried to the ionosphere through thunderstorms, and its value depends on highly electrically mobile ion concentrations, hence local conductivity of the air. Ions attach to aerosol in the atmosphere, reducing their mobility and therefore increasing the potential gradient, and so potential gradient measurements have been suggested as a proxy for aerosol measurements. Particle number count, size distribution and potential gradient were measured for two campaigns in Manchester, U.K., and one campaign in Bristol, U.K. Using a factor based on size distribution to account for preferential attachment at larger sizes provided the best relationship with potential gradient, but particle count alone showed a weaker, but similar relationship. The increase in particle count caused by annual bonfire and fireworks celebrations (November) was evidenced in both potential gradient and particle numbers. Daily regression or correlation did not show a consistent relationship. In the larger Bristol data set, increasing humidity led to a reduction of potential gradient, while increasing particle number led to an increase.

Effects of strength training with blood flow restriction on torque, muscle activation and local muscular endurance in healthy subjects

The present study aimed to analyse the effects of six weeks of strength training (ST), with and without blood flow restriction (BFR), on torque, muscle activation, and local muscular endurance (LME) of the knee extensors. Thirty-seven healthy young individuals were divided into four groups: high intensity (HI), low intensity with BFR (LI+BFR), high intensity and low intensity + BFR (COMB), and low intensity (LI). Torque, muscle activation and LME were evaluated before the test and at the 2nd, 4th and 6th weeks after exercise. All groups had increased torque, muscle activation and LME (p<0.05) after the intervention, but the effect size and magnitude were greater in the HI, LI+BFR and COMB groups. In conclusion, the groups with BFR (LI+BFR and COMB) produced magnitudes of muscle activation, torque and LME similar to those of the HI group.

Flower development and sex specification in wild grapevine

BACKGROUND

Wild plants of Vitis closely related to the cultivated grapevine (V. v. vinifera) are believed to have been first domesticated 10,000 years BC around the Caspian Sea. V. v. vinifera is hermaphrodite whereas V. v. sylvestris is a dioecious species. Male flowers show a reduced pistil without style or stigma and female flowers present reflexed stamens with infertile pollen. V. vinifera produce perfect flowers with all functional structures. The mechanism for flower sex determination and specification in grapevine is still unknown.

RESULTS

To understand which genes are involved during the establishment of male, female and complete flowers, we analysed and compared the transcription profiles of four developmental stages of the three genders. We showed that sex determination is a late event during flower development and that the expression of genes from the ABCDE model is not directly correlated with the establishment of sexual dimorphism. We propose a temporal comprehensive model in which two mutations in two linked genes could be players in sex determination and indirectly establish the Vitis domestication process. Additionally, we also found clusters of genes differentially expressed between genders and between developmental stages that suggest a role involved in sex differentiation. Also, the detection of differentially transcribed regions that extended existing gene models (intergenic regions) between sexes suggests that they may account for some of the variation between the subspecies.

CONCLUSIONS

There is no evidence of differences of expression levels in genes from the ABCDE model that could explain the shift from hermaphroditism to dioecy. We propose that sex specification occurs after floral organ identity has been established and therefore, sex determination genes might be having an effect downstream of the ABCDE model genes.For the first time a full transcriptomic analysis was performed in different flower developmental stages in the same individual. Our experimental approach enabled us to create a comprehensive catalogue of transcribed genes across developmental stages and genders that will contribute for future work in sex determination in seed plants.

Coherent transport in high performance double magnetic junctions

Spin-dependent transport is considered in double magnetic tunnel junctions of two types F-I-F-I-F and F-I-N-I-F with thin insulating (I) barriers between the ferromagnetic (F) or non-magnetic (N) electrodes. Using the Landauer formalism within single-band tight-binding dynamics for atomically perfect epitaxial multilayers, the dependencies of tunnel magnetoresistance (TMR) on the on-site atomic energies epsilonI or epsilonN and number nI of atomic planes in the respective layers are obtained. It is found that the maximum TMR corresponds to the "shallow band" regime with respect to epsilonN and a series of peaks appears with respect to nI, essentially enhancing the performance of a simple F-I-F junction. These results suggest the material and structural choices for optimum TMR devices of advanced compositions.

Infection by Cryptosporidium parvum in renal patients submitted to renal transplant or hemodialysis

The frequency of infection by Cryptosporidium parvum was determined in two groups of renal patients submitted to immunosuppression. One group consisted of 23 renal transplanted individuals, and the other consisted of 32 patients with chronic renal insufficiency, periodically submitted to hemodialysis. A third group of 27 patients with systemic arterial hypertension, not immunosuppressed, was used as control. During a period of 18 months all the patients were submitted to faecal examination to detect C. parvum oocysts, for a total of 1 to 6 tests per patient. The results showed frequencies of C. parvum infection of 34.8%, 25% and 17.4%, respectively, for the renal transplanted group, the patients submitted to hemodialysis and the control group. Statistical analysis showed no significant differences among the three groups even though the frequency of C. parvum infection was higher in the transplanted group. However, when the number of fecal samples containing C. parvum oocysts was taken in account, a significantly higher frequency was found in the renal transplanted group.

Acute renal failure due to hemolytic uremic syndrome in adult patients

Hemolytic uremic syndrome is characterized by the simultaneous occurrence of hemolytic anemia, thrombocytopenia, and renal failure. Clinical/ pathologic data, along with the treatment and outcome of 8 adult patients with HUS, are described. There were 7 females and 1 male, age 30.7 +/- 12 years; 7 were White and 1 Black. Three patients were kidney graft recipients, 2 of whom were receiving cyclosporine; 2 patients were postpartum; 1 case followed an abortion; 1 occurred with prodromic infection; and 1 case was without a causal factor. All patients presented with hematuria and 6 with oligoanuria. Laboratory data showed hemolytic anemia with schistocytes, LDH values were 2584 +/- 2191 U/L, platelets were 79,000 +/- 40,000/mL, creatinine concentrations were 5.9 +/- 2.5 mg/dL. Renal biopsy showed thrombotic microangiopathy. Two had predominant glomerular involvement. 2 showed renal cortical necrosis, 4 were marked by predominant arteriolar involvement. In 5 patients dialytic therapy was performed. All were treated with fresh-frozen plasma infusion and 6 with plasmapheresis. Three patients died, 2 without recovery of renal function. In conclusion, the trigger events were related to renal transplant in 3.2 of them taking cyclosporine; 3 with pregnancy; 1 to precedent infection; and 1 with no causal factor. There was no correlation between histological form and outcome in this group of patients. The benefit of plasmapheresis was evident in the recovery of the extrarenal manifestations, although it did not change the renal outcome. The prognosis is poor, with a high mortality (37.5%) and/or end-stage renal failure (37.5%). Complete recovery of renal function was obtained in 25%.