Variation between three Eremanthus (Asteraceae) species in their ability to form a seed bank

Knowledge on seed bank function is fundamental for understanding the species regeneration patterns. This investigation was carried out to compare the ability of Eremanthus elaeagnus (Mart. ex DC.) Schultz-Bip, E. glomerulatus Less., and E. incanus (Less.) Less. to form a soil seed bank. Seeds (aquenes) of each of these three species were collected, stored in the laboratory and subsequently buried in the same area where they were collected, inside nylon bags. The bags were collected monthly or bimonthly for germination tests under continuous light and also in darkness at 20 °C (E. elaeagnus e E. glomerulatus) and at 25 °C (E. incanus). After 12 months, a further series of tests compared the germination of achenes that had been buried in soil and compared with those stored in the laboratory at 15, 20, 25, 30, 35, and 40 °C. After three months of burial, the seeds of E. elaeagnus and E. glomerulatus failed to germinate, whereas the seeds of E. incanus, even after burial for 18 months, retained germination percentage of between 1% and 30%. After one year stored in laboratory, the seeds of E. glomerulatus were no longer viable and seeds of E. elaeagnus e E. incanus had a germination percentage below that of newly collected seeds. The results showed that E. elaeagnus and E. glomerulatus do not form seed banks while E. incanus may form a small and persistent soil seed bank.

Intrapopulational chromosome number variation in Zephyranthes sylvatica Baker (Amaryllidaceae: Hippeastreae) from Northeast Brazil

Zephyranthes Herb. is a taxonomically complex and cytologically variable group, with about 65 species of Neotropical distribution. Chromosome number variability in 32 individuals of a Zephyranthes sylvatica population from Northeast Brazil was investigated. Three cytotypes were found: 2n = 12 (one metacentric, four submetacentric and one acrocentric pairs), in 24 individuals; 2n = 12 + 1B, in five and three individuals with 2n = 18, a triploid cytotype. All diploid individuals showed chromosomes with polymorphism in pair one and two, while in triploids this polymorphism was observed in all chromosome triplets, generally with two homomorphic chromosomes and a higher or lower heteromorphic chromosome. All individuals had reticulated interfasic nucleus and a slightly asymmetric chromosome complement, with one metacentric chromosome pair and the others more submetacentric to acrocentric. These data confirm the cytological variability previously registered for the genus. Mechanisms involved in karyotypic evolution in this population are discussed.

Variation in nitrogen use strategies and photosynthetic pathways among vascular epiphytes in the Brazilian Central Amazon

The variation in nitrogen use strategies and photosynthetic pathways among vascular epiphyte families was addressed in a white-sand vegetation in the Brazilian Central Amazon. Foliar nitrogen and carbon concentrations and their isotopic composition (δ15N and δ13C, respectively) were measured in epiphytes (Araceae, Bromeliaceae and Orchidaceae) and their host trees. The host tree Aldina heterophylla had higher foliar N concentration and lower C:N ratio (2.1 ± 0.06% and 23.6 ± 0.8) than its dwellers. Tree foliar δ15N differed only from that of the orchids. Comparing the epiphyte families, the aroids had the highest foliar N concentration and lowest C:N ratios (1.4 ± 0.1% and 34.9 ± 4.2, respectively). The orchids had more negative foliar δ15N values (-3.5 ± 0.2‰) than the aroids (-1.9 ± 0.7‰) and the bromeliads (-1.1 ± 0.6‰). Within each family, aroid and orchid taxa differed in relation to foliar N concentrations and C:N ratios, whereas no internal variation was detected within bromeliads. The differences in foliar δ15N observed herein seem to be related to the differential reliance on the available N sources for epiphytes, as well as to the microhabitat quality within the canopy. In relation to epiphyte foliar δ13C, the majority of epiphytes use the water-conserving CAM-pathway (δ13C values around -17‰), commonly associated with plants that live under limited and intermittent water supply. Only the aroids and one orchid taxon indicated the use of C3-pathway (δ13C values around -30‰).

Allozyme variation in a natural population of Stryphnodendron adstringens in the Rio Preto State Park, southeastern Brazil

Leaves and fruits from 63 Stryphnodendron adstringens trees were sampled in the Rio Preto State Park to analyze allozyme segregation, tissue specific expression of allozyme loci, and their genetic parameters. The enzyme systems ADH, EST, ACP, PGM, PGI, GDH, G6PDH, GOT, IDH, LAP, MDH, PER and SKDH were assessed by means of starch-gel electrophoresis. The polymorphic systems PGI, IDH, MDH and GOT demonstrated a dimeric quaternary structure, while EST and PER were monomeric. The total expected genetic diversity (H E) for leaves and seeds were 0.325 and 0.244 respectively. The effective number of alleles per locus (A E) was 1.58 in leaves and 1.42 in seeds. The values of H E and A E observed in S. adstringens were comparatively higher than the average values seen in allozyme studies of other woody plants. The values of the fixation indices for the population, considering leaves (f = 0.070) and seeds (f = 0.107), were not significant. The high values of genetic diversity and of effective number of alleles per locus, as well as the non-significant fixation index and the adjustments of the Hardy-Weinberg proportions between generations for the pgi-1, mdh-2 and idh-1 loci, indicated random mating in this population. The enzyme systems EST and PER demonstrated their best resolution in leaf tissues, while the MDH, IDH, PGI and GOT systems demonstrated their best resolution in seed tissues.

Chromosome number and secondary constriction variation in 51 accessions of a citrus germplasm bank

The mitotic chromosomes of 51 citrus accessions from the Centro Nacional de Pesquisa em Mandioca e Fruticultura Tropical, Cruz das Almas, BA, Brazil, were analyzed. The sample included representatives of 20 Citrus species, one of Poncirus and seven hybrids. All accessions showed 2n = 18 without any evidence of numerical variation. The most clearly variable karyotype feature was the number and position of secondary constrictions (SECs). In 19 accessions the SECs were not identified, mainly due to the degree of chromatin condensation. In the remainder they varied in number from one to three per karyotype. They were found in the proximal region of one of the three largest chromosome pairs, in the terminal/subterminal region of a smaller chromosome or, more seldom, terminally in a larger chromosome. Only in a few cases were such constrictions observed simultaneously in both homologues of the same chromosome pair. The high variability of this karyotype feature may be due to the activation of this region in the previous interphase but may also indicate a high structural variability and heterozygosity of citrus germplasms

Release of plasma atrial natriuretic peptide after volume expansion is not related to pituitary-adrenal axis diurnal variation in normal subjects

The existence of a circadian rhythm of atrial natriuretic peptide (ANP) in humans is controversial. We studied the plasma ANP response to isotonic blood volume expansion in the morning and in the afternoon and its relationship with adrenocorticotropic hormone (ACTH)-cortisol diurnal variation in seven normal subjects. Basal plasma ANP level was similar in the morning (19.6 ± 2.4 pg/ml) and in the afternoon (21.8 ± 4.8 pg/ml). The ANP peak obtained with saline infusion (0.9% NaCl, 12 ml/kg) in the morning (49.4 ± 8 pg/ml) did not differ from that obtained in the afternoon (60.3 ± 10.1 pg/ml). There was no correlation between the individual mean cortisol and ACTH levels and the ANP peak obtained with saline infusion. These data indicate no diurnal variation in plasma ANP secretion induced by blood volume expansion and no relationship between plasma ANP peak and ACTH-cortisol diurnal variation

Probable effect of photoperiod on seasonal variation in the nuclear volume of the adrenal cortex of viscacha (Lagostomus maximus maximus)

The neuroendocrine system regulates several organic functions such as reproduction, metabolism and adaptation to the environment. This system shows seasonal changes linked to the environment. The experimental model used in the present study was Lagostomus maximus maximus (viscacha). The reproduction of males of this species is photoperiod dependent. Twenty-four adult male viscachas were captured in their habitat at different times during one year. The adrenal glands were processed for light microscopy. Serial cuts were stained with hematoxylin-eosin for the morphometric study, and 100 nuclei of each zone of the adrenal cortex were counted per animal. Data were analyzed statistically by ANOVA and the Tukey test. The cells of the glomerulosa zone are arranged in a tube-shaped structure. The fasciculata zone has large cells with central nuclei and clearly visible nucleoli and with a vacuolar cytoplasm. In the reticularis zone there are two of types of cells, one with a nucleus of fine chromatin and a clearly visible nucleolus and the other with nuclear pycnosis. Morphometric analysis showed maximum nuclear volumes during the February-March period with values of 133 ± 7.3 µm3 for the glomerulosa, 286.4 ± 14.72 µm3 for the fasciculata, and 126.3 ± 9.49 µm3 for the reticularis. Minimum nuclear volumes were observed in August with values of 88.24 ± 9.9 µm3 for the glomerulosa, 163.7 ± 7.78 µm3 for the fasciculata and 64.58 ± 4.53 µm3 for the reticularis. The short winter photoperiod to which viscacha is subjected could inhibit the adrenal cortex through a melatonin increase which reduces the nuclear volume as well as the cellular activity.

In situ variation of cervical mucus pH during exposure to atmospheric air

The objective of the present study was to determine if exposure of cervical mucus to air during specular examination could modify mucus pH. Detection of changes is justified because of their possible interference with sperm-mucus interaction, since an acidic pH is unfavorable to sperm penetration and is associated with infertility due to the cervical factor. Twenty women with good quality mucus were evaluated. pH measurements of ecto- and endocervical mucus were made in situ using a glass electrode after 0-, 5- and 10-min exposure to air. There was a progressive alkalinization of mucus pH. Mean values of ectocervical mucus pH were 6.91, 7.16 and 7.27, while mean values of endocervical mucus pH were 7.09, 7.34 and 7.46 at 0, 5 and 10 min, respectively. Significant differences were found between the mean values obtained at 0 and 5 min, and at 0 and 10 min (P<0.05), whereas the differences in mean values at 5 and 10 min were not significant at either site. We conclude that 5 to 10 min of exposure to atmospheric air affects cervical mucus pH in a significant way. Since tests used to evaluate sperm-mucus interaction generally have not considered this possibility, we suggest that they should be performed immediately after mucus collection in order to avoid misinterpretation of the results.

Low variation in ribosomal DNA and internal transcribed spacers of the symbiotic fungi of leaf-cutting ants (Attini: Formicidae)

Leaf-cutting ants of the genera Atta and Acromyrmex (tribe Attini) are symbiotic with basidiomycete fungi of the genus Leucoagaricus (tribe Leucocoprineae), which they cultivate on vegetable matter inside their nests. We determined the variation of the 28S, 18S, and 5.8S ribosomal DNA (rDNA) gene loci and the rapidly evolving internal transcribed spacers 1 and 2 (ITS1 and ITS2) of 15 sympatric and allopatric fungi associated with colonies of 11 species of leafcutter ants living up to 2,600 km apart in Brazil. We found that the fungal rDNA and ITS sequences from different species of ants were identical (or nearly identical) to each other, whereas 10 GenBank Leucoagaricus species showed higher ITS variation. Our findings suggest that Atta and Acromyrmex leafcutters living in geographic sites that are very distant from each other cultivate a single fungal species made up of closely related lineages of Leucoagaricus gongylophorus. We discuss the strikingly high similarity in the ITS1 and ITS2 regions of the Atta and Acromyrmex symbiotic L. gongylophorus studied by us, in contrast to the lower similarity displayed by their non-symbiotic counterparts. We suggest that the similarity of our L. gongylophorus isolates is an indication of the recent association of the fungus with these ants, and propose that both the intense lateral transmission of fungal material within leafcutter nests and the selection of more adapted fungal strains are involved in the homogenization of the symbiotic fungal stock.

Description of Lyme disease-like syndrome in Brazil: is it a new tick borne disease or Lyme disease variation?

An emerging clinical entity that reproduces clinical manifestations similar to those observed in Lyme disease (LD) has been recently under discussion in Brazil. Due to etiological and laboratory particularities it is named LD-like syndrome or LD imitator syndrome. The condition is considered to be a zoonosis transmitted by ticks of the genus Amblyomma, possibly caused by interaction of multiple fastidious microorganisms originating a protean clinical picture, including neurological, osteoarticular and erythema migrans-like lesions. When peripheral blood of patients with LD-like syndrome is viewed under a dark-field microscope, mobile uncultivable spirochete-like bacteria are observed. PCR carried out with specific or conservative primers to recognize Borrelia burgdorferi sensu stricto or the genus Borrelia has been negative in ticks and in biological samples. Two different procedures, respectively involving hematoxylin and eosin staining of cerebrospinal fluid and electron microscopy analysis of blood, have revealed spirochetes not belonging to the genera Borrelia, Leptospira or Treponema. Surprisingly, co-infection with microorganisms resembling Mycoplasma and Chlamydia was observed on one occasion by electron microscopy analysis. We discuss here the possible existence of a new tick-borne disease in Brazil imitating LD, except for a higher frequency of recurrence episodes observed along prolonged clinical follow-up.

Diurnal variation of vascular diameter and reactivity in healthy young men

The higher incidence of cardiovascular events in the morning is accompanied by an increased vascular tone. However, there are few published studies designed to evaluate the diurnal variation of vascular and endothelial parameters in healthy subjects. In the present investigation, we evaluated the diurnal variation in brachial artery diameter (BAD), flow-mediated dilation (FMD) and endothelium-independent dilation (NFMD) in a homogeneous sample of healthy non-smoker young men. Fifty subjects aged 20.8 ± 0.3 years (range: 18 to 25 years) were investigated by brachial artery ultrasound. Exclusion criteria were female gender and evidence of clinically significant health problems, including obesity. Volunteers were asked to rest and avoid fat meals as well as alcoholic beverages 48 h before and until completion of the evaluations. BAD, FMD and NFMD were measured at 7 am, 5 pm, and 10 pm and tested by repeated measures ANOVA. BAD was smaller at 7 am (mean ± SEM, 3.8 ± 0.1 mm) in comparison with 5 pm (3.9 ± 0.1) and 10 pm (4.0 ± 0.1 mm; P < 0.001). FMD values did not change significantly during the day, while NFMD increased more at 7 am (18.5 ± 1.1%), when compared to 15.5 ± 0.9% at 10 pm and 15.5 ± 0.9% at 5 pm (P = 0.04). The physiological state of vasoconstriction after awakening, with preserved capability to dilate in the morning, should be considered to be part of the healthy cardiovascular adaptation before considering later life risk factors and endothelial dysfunction.

NAA and NAAG variation in neuronal activation during visual stimulation

N-acetyl-aspartyl-glutamate (NAAG) and its hydrolysis product N-acetyl-L-aspartate (NAA) are among the most important brain metabolites. NAA is a marker of neuron integrity and viability, while NAAG modulates glutamate release and may have a role in neuroprotection and synaptic plasticity. Investigating on a quantitative basis the role of these metabolites in brain metabolism in vivo by magnetic resonance spectroscopy (MRS) is a major challenge since the main signals of NAA and NAAG largely overlap. This is a preliminary study in which we evaluated NAA and NAAG changes during a visual stimulation experiment using functional MRS. The paradigm used consisted of a rest period (5 min and 20 s), followed by a stimulation period (10 min and 40 s) and another rest period (10 min and 40 s). MRS from 17 healthy subjects were acquired at 3T with TR/TE = 2000/288 ms. Spectra were averaged over subjects and quantified with LCModel. The main outcomes were that NAA concentration decreased by about 20% with the stimulus, while the concentration of NAAG concomitantly increased by about 200%. Such variations fall into models for the energy metabolism underlying neuronal activation that point to NAAG as being responsible for the hyperemic vascular response that causes the BOLD signal. They also agree with the fact that NAAG and NAA are present in the brain at a ratio of about 1:10, and with the fact that the only known metabolic pathway for NAAG synthesis is from NAA and glutamate.

Industrialized cashew juices: variation of ascorbic acid and other physicochemical parameters

Commercial cashew apple juice is widely accepted in the Brazilian market. Cashew apple has high content of ascorbic acid, an important nutrient to human beings. Ascorbic acid content in food can be affected by processing and storage conditions. Commercial cashew apple juice samples, ready-to-drink and concentrated, were analyzed. The ascorbic acid content, total titratable acidity, total soluble solids, and pH of the juices were determined during storage at 4 °C after the containers were opened. The ascorbic acid content presented a great variability among the samples analyzed ranging from 37.3 to 46.3 mg.100 mL-1 in ready-to-drink juices and from 75.7 to 152 mg.100 mL-1 in concentrated juices. The storage of commercial cashew apple juices for 48 hours at 4 °C resulted in ascorbic acid losses of up to 8.8% for concentrated and 6.4% for ready-to-drink juices. The other parameters remained stable during storage. The results of this study point to the importance of considering ascorbic acid losses in commercial cashew apple juices which occurs after opening but before the expiration date expires.

Variation of glucoraphanin and glucobrassicin: anticancer components in Brassica during processing

Effects of cold storage and three common cooking practices, blanching, sauteing, and microwave cooking at different time intervals, on the content of glucosinolate (GSL) anticancer components in six Brassica vegetables were investigated. Eleven GSLs including progoitrin, glucoraphanin, sinigrin, glucoalyssin, gluconapin, glucobrassicanapin, glucoerucin, glucobrassicin, 4-methoxyglucobrassicin, gluconasturtiin, and neoglucobrassicin were quantified using LC-MS and HPLC. Storage at 4 ºC indicated no significant loss of GSLs in broccoli, kohlrabi, and cabbage, and approximately 90-100% of the total concentration of aliphatic and indolyl GSLs were detected. Interestingly, glucoraphanin and glucobrassicin, known as a cancer prevention agents, increased approximately above 50% in broccoli, kohlrabi, and cabbage, while the amount of glucobrassicin decreased by 5% in cauliflower for 5 days at 4 ºC. Blanching of broccoli at 120 sec significantly (36%) decreased total GSLs; however, sautéing and microwaving decreased by13-26%. Individual GSLs have different response at blanching. These findings suggest that different processing methods for each vegetable would be preferred to preserve the nutritional qualities.

Variation of some chemical and functional properties of Bambara groundnut (Voandzeia Subterranean L. Thouars) during sort time storage

Abstract The storage susceptibility of Bambara groundnut (B. G.) (Voandzeia Subterranean (L.) Thouars) to Callosobruchus maculatus and chemical and functional properties of 11 varieties form Far-North of Cameroon were investigate using standard analytical methods. Storage susceptibility shown that, after five months within treatment, C. maculatus destroy 10 to 50% of grains. The chemical characteristics of none attack grains of 11 varieties were range to 18.64 at 21.08%, 6.85 at 7.44%, 49.75 at 52.68% and to 6.05 at 7.55% respectively for protein, fat, starch and free carbohydrate. These chemical characteristics significantly (p < 0.05) decreases form attacks varieties. For the functional parameters, the none attacks grains was range of 130 at 135%, 19.15 at 20.91%, 18.20 at 21.13%, 2.76 at 3.21% and of 8.54 at 10.14% respectively for water capacity absorption, solubility index, gel length, ash and humidity. The results of this study indicated that storage susceptibility, chemical and functional properties of B. G. be dependant to the varieties.