Further evidence of a role for abscisic acid in conversion of somatic embryos ofDaucus carota

Summary Somatic embryogenesis has been shown to be an imperfect recapitulation of stages involved to form embryos from vegetative tissues. Although abscisic acid has been implicated in normalizing development, studies that specifically investigate conversion (vegetative leaf initiation) in somatic embryos are lacking. This report documents a follow-up of a study that implicated abscisic acid as a vital factor in allowing embryos ofDaucus carota to progress to the plantlet stage. Abscisic acid was determined to enhance conversion at doses ranging from 1 to 50 µM. Younger embryo stages were more responsive to abscisic acid application with regards to plantlet recovery. Pulses of abscisic acid were shown to elicit more rapid response with younger embryo stages, indicating more plastic development. Fluridone, an abscisic acid synthesis inhibitor, was shown to dramatically reduce conversion, even at low doses (<5µM). When abscisic acid was applied concurrently with fluridone, partial restoration of conversion was observed. Histologically, fluridone was seen to cause pronounced vacuolation in the shoot apical notch which resulted in the loss of meristematic cells, negating conversion capacity. Quantitation of total cytoplasmic area showed that abscisic acid reduced vacuolar intrusion into the apical notch, while fluridone caused a significant increase in vacuolation of cells in this region. This report documents further evidence of a role for abscisic acid in plantlet establishment from somatic embryos ofDaucus carota.     

On the Taxonomy and Morphology of the Pine Wood Nematode, Bursaphelenchus xylophilus (Steiner &Buhrer 1934) Nickle 1970

During the past 3 yr, nematologists in the United States have found specimens of Bursaphelenchus sp. in the wood of dead and dying pine trees. This nematode-host association resembles a similar interaction reported from Japan where pine trees are being killed by the pine wood nematode. This taxonomic research was conducted to determine if the Japanese pine wood nematode and similar populations in the United States are of the same species. Based upon typical morphological characters of original specimens of Bursaphelenchus xylophilus (Steiner and Buhrer 1934) Nickle 1970 that were rediscovered in the USDA Nematode Collection and genetic crosses among the Japanese and American nematode populations, it was concluded that they are all the same species, B. xylophilus.     

Intratumor heterogeneity of biomarker expression in breast carcinomas

Small biopsy samples are used increasingly to assess the biomarker expression for prognostic information and for monitoring therapeutic responses prior to and during neoadjuvant therapy. The issue of intratumor heterogeneity of expression of biomarkers, however, has raised questions about the validity of the assessment of biomarker expression based on limited tissue samples. We examined immunohistochemically the expression of HER-2neu (p185^erbB-2), epidermal growth factor receptor (EGFR), Bcl-2, p53, and proliferating cell nuclear antigen (PCNA) in 30 breast carcinomas using archived, paraffin embedded tissue and determined the extent of intratumor heterogeneity. Each section was divided into four randomly oriented discrete regions, each containing a portion of the infiltrating carcinoma. For each tumor, the entire lesion and four regions were analyzed for the expression of these markers. Scores of both membrane and cytoplasmic staining of HER-2neu and EGFR, scores of cytoplasmic staining of Bcl-2, and scores of nuclear staining of both p53 and PCNA were recorded. The intensity of staining and the proportion of immunostained cells were determined. A semiquantitative immunoscore was calculated by determining the sum of the products of the intensity and corresponding proportion of stained tumor cells. We analyzed both invasive (IDC) and in situ (DCIS) carcinomas. The Wilcoxon signed-rank test was used for paired comparisons between overall and regional immunoscores and between overall and regional percentages of stained cells. Spearman's correlation coefficients were used to assess the level of agreement of overall biomarker expression with each of the regions. Generalized linear models were used to assess overall and pair-wise differences in the absolute values of percent changes between overall and regional expression of biomarkers. For IDCs, there were no statistically significant differences in the expression of the biomarkers in terms of either the percentage of cells staining or the immunoscores when comparing the entire tumor with each region except for the lower EGFR expression of arbitrarily selected region 1 and lower p53 expression of region 1 compared to that of the entire tumor section. For DCIS, there were no statistically significant differences in the expression of the biomarkers between the entire tumor and each region except in PCNA of region 2 compared to that of entire tumor section. Positive correlation of immunoscores was observed between the entire tumor and each region as well as across all four regions for IDC. Similar observations were noted with DCIS except for HER-2neu and PCNA. No statistically significant differences were observed in the absolute values of percent changes of biomarker expression between overall and the four regions for both DCIS and IDC. Therefore, no significant intratumor heterogeneity in the expression of HER-2neu, Bcl-2, and PCNA was observed in IDC. Minor regional variations were observed for EGFR and p53 in IDC. Similarly, no significant regional variation in the expression of markers was observed in DCIS except for PCNA.     

Extensive intrasubtype recombination in South African human immunodeficiency virus type 1 subtype C infections

Recombinant human immunodeficiency virus type 1 (HIV-1) strains containing sequences from different viral genetic subtypes (intersubtype) and different lineages from within the same subtype (intrasubtype) have been observed. A consequence of recombination can be the distortion of the phylogenetic signal. Several intersubtype recombinants have been identified; however, less is known about the frequency of intrasubtype recombination. For this study, near-full-length HIV-1 subtype C genomes from 270 individuals were evaluated for the presence of intrasubtype recombination. A sliding window schema (window, 2 kb; step, 385 bp) was used to partition the aligned sequences. The Shimodaira-Hasegawa test detected significant topological incongruence in 99.6% of the comparisons of the maximum-likelihood trees generated from each sequence partition, a result that could be explained by recombination. Using RECOMBINE, we detected significant levels of recombination using five random subsets of the sequences. With a set of 23 topologically consistent sequences used as references, bootscanning followed by the interactive informative site test defined recombination breakpoints. Using two multiple-comparison correction methods, 47% of the sequences showed significant evidence of recombination in both analyses. Estimated evolutionary rates were revised from 0.51%/year (95% confidence interval [CI], 0.39 to 0.53%) with all sequences to 0.46%/year (95% CI, 0.38 to 0.48%) with the putative recombinants removed. The timing of the subtype C epidemic origin was revised from 1961 (95% CI, 1947 to 1962) with all sequences to 1958 (95% CI, 1949 to 1960) with the putative recombinants removed. Thus, intrasubtype recombinants are common within the subtype C epidemic and these impact analyses of HIV-1 evolution.     

Polymerase chain reaction detection of Leishmania DNA in skin biopsy samples in Sri Lanka where the causative agent of cutaneous leishmaniasis is Leishmania donovani

Leishmania donovani is the known causative agent of both cutaneous (CL) and visceral leishmaniasis in Sri Lanka. CL is considered to be under-reported partly due to relatively poor sensitivity and specificity of microscopic diagnosis. We compared robustness of three previously described polymerase chain reaction (PCR) based methods to detectLeishmania DNA in 38 punch biopsy samples from patients presented with suspected lesions in 2010. Both, Leishmaniagenus-specific JW11/JW12 KDNA and LITSR/L5.8S internal transcribed spacer (ITS)1 PCR assays detected 92% (35/38) of the samples whereas a KDNA assay specific forL. donovani (LdF/LdR) detected only 71% (27/38) of samples. All positive samples showed a L. donovani banding pattern upon HaeIII ITS1 PCR-restriction fragment length polymorphism analysis. PCR assay specificity was evaluated in samples containing Mycobacterium tuberculosis, Mycobacterium leprae, and human DNA, and there was no cross-amplification in JW11/JW12 and LITSR/L5.8S PCR assays. The LdF/LdR PCR assay did not amplify M. leprae or human DNA although 500 bp and 700 bp bands were observed in M. tuberculosis samples. In conclusion, it was successfully shown in this study that it is possible to diagnose Sri Lankan CL with high accuracy, to genus and species identification, using Leishmania DNA PCR assays.     

Similar hypotensive responses to resistance exercise with and without blood flow restriction

Low intensity resistance exercise (RE) with blood flow restriction (BFR) has gained attention in the literature due to the beneficial effects on functional and morphological variables, similar to those observed during traditional RE without BFR, while the effects of BFR on post-exercise hypotension remain unclear. The aim of the present study was to compare the blood pressure (BP) response of trained normotensive individuals to RE with and without BFR. In this cross-over randomized trial, eight male subjects (23.8 ± 4 years, 74 ± 3 kg, 174 ± 4 cm) completed two exercise protocols: traditional RE (3 x 10 repetitions at 70% one-repetition maximum [1-RM]) and low intensity RE (3 x 15 repetitions at 20% 1-RM) with BFR. Blood pressure measurements were performed after 15 min of seated rest (0), immediately after and 10 min, 20 min, 30 min, 40 min, 50 min and 60 min after the experimental sessions. Similar hypotensive effects for systolic BP (SBP) were observed for both protocols (P < 0.05) after exercise, with no differences between groups (P > 0.05) and no statistically significant difference for diastolic BP (P > 0.05). These results suggest that in normotensive trained individuals, both traditional RE and RE with BFR induce hypotension for SBP, which is important to prevent cardiovascular disturbances.     

Effects of general,specific and combined warm-up on explosive muscular performance

The purpose of this study was to compare the acute effects of general, specific and combined warm-up (WU) on explosive performance. Healthy male (n = 10) subjects participated in six WU protocols in a crossover randomized study design. Protocols were: passive rest (PR; 15 min of passive rest), running (Run; 5 min of running at 70% of maximum heart rate), stretching (STR; 5 min of static stretching exercise), jumping [Jump; 5 min of jumping exercises – 3x8 countermovement jumps (CMJ) and 3x8 drop jumps from 60 cm (DJ60)], and combined (COM; protocols Run+STR+Jump combined). Immediately before and after each WU, subjects were assessed for explosive concentric-only (i.e. squat jump – SJ), slow stretch-shortening cycle (i.e. CMJ), fast stretch-shortening cycle (i.e. DJ60) and contact time (CT) muscle performance. PR significantly reduced SJ performance (p =0.007). Run increased SJ (p =0.0001) and CMJ (p =0.002). STR increased CMJ (p =0.048). Specific WU (i.e. Jump) increased SJ (p =0.001), CMJ (p =0.028) and DJ60 (p =0.006) performance. COM increased CMJ performance (p =0.006). Jump was superior in SJ performance vs. PR (p =0.001). Jump reduced (p =0.03) CT in DJ60. In conclusion, general, specific and combined WU increase slow stretch-shortening cycle (SSC) muscle performance, but only specific WU increases fast SSC muscle performance. Therefore, to increase fast SSC performance, specific fast SSC muscle actions must be included during the WU.