The analysis of the genetic variation and evolutionary processes related to the conservation and use of forest genetic resources requires reliable tools. The aim of the present study is to determine the mode of inheritance of isozyme variants of Nothofagus antarctica, species of economic and ecological importance inhabiting the temperate forests of southern South America. Buds from 56 trees and their offspring were subjected to horizontal starch gel electrophoresis. Good resolution and consistent band patterns were obtained from five out of 15 enzyme systems surveyed. Expected equal number of heterozygous and homozygous seedlings of open pollination from a putative heterozygous mother was tested by the Chi-square test. Superoxide dismutase (SOD) revealed invariant electrophoretic patterns. Glutamate-oxalacetate transaminase (GOT) showed two zones of enzymatic activity, each one encoded by a gene locus with codominant expression and three alleles. Phosphoglucose isomerase (PGI) and phosphoglucomutase (PGM) showed two zones, the most anodal of which were invariant, and six and five alleles respectively in the variable zone. Four confident polymorphic gene markers are thus available for different population genetics studies on Nothofagus antarctica.

El análisis de la variación genética y de diversos procesos evolutivos en relación con la conservación y uso de los recursos genéticos forestales requiere la utilización de herramientas confiables. El objetivo del presente estudio es determinar el modo de herencia de variantes isoenzimáticas en Nothofagus antarctica, una especie de los bosques templados de Sudamérica de gran importancia tanto económica como ecológica. Las yemas de 56 árboles adultos y plántulas de su descendencia se analizaron electroforéticamente sobre gel horizontal de almidón. Se obtuvo buena resolución y patrones de bandas consistentes en cinco de los 15 sistemas enzimáticos ensayados. Mediante el test de Chi-cuadrado se puso a prueba la hipótesis esperada de igualdad entre las frecuencias de plántulas homocigotas y heterocigotas en la descendencia de polinización abierta de madres heterocigotas putativas. La enzima superóxido dismutasa (SOD) reveló un patrón electroforético invariable. Glutamato-oxalacetato transaminasa (GOT) mostró dos zonas de actividad enzimática, cada una codificada por un gen-locus codominante y tres alelos. También se observaron dos zonas en fosfoglucosa isomerasa (PGI) y en fosfoglucomutasa (PGM), invariables las más anódicas en ambos casos, y con seis y cinco alelos respectivamente en la zona variable de cada una de estas enzimas. De este modo se dispone de cuatro marcadores génicos polimórficos confiables para llevar a cabo diversos estudios genéticos en Nothofagus antarctica.

The purpose of the present study was to evaluate the effects of aerobic physical training (APT) on heart rate variability (HRV) and cardiorespiratory responses at peak condition and ventilatory anaerobic threshold. Ten young (Y: median = 21 years) and seven middle-aged (MA = 53 years) healthy sedentary men were studied. Dynamic exercise tests were performed on a cycloergometer using a continuous ramp protocol (12 to 20 W/min) until exhaustion. A dynamic 24-h electrocardiogram was analyzed by time (TD) (standard deviation of mean R-R intervals) and frequency domain (FD) methods. The power spectral components were expressed as absolute (a) and normalized units (nu) at low (LF) and high (HF) frequencies and as the LF/HF ratio. Control (C) condition: HRV in TD (Y: 108, MA: 96 ms; P<0.05) and FD - LFa, HFa - was significantly higher in young (1030; 2589 ms²/Hz) than in middle-aged men (357; 342 ms²/Hz) only during sleep (P<0.05); post-training effects: resting bradycardia (P<0.05) in the awake condition in both groups; VO2 increased for both groups at anaerobic threshold (P<0.05), and at peak condition only in young men; HRV in TD and FD (a and nu) was not significantly changed by training in either groups. The vagal predominance during sleep is reduced with aging. The resting bradycardia induced by short-term APT in both age groups suggests that this adaptation is much more related to intrinsic alterations in sinus node than in efferent vagal-sympathetic modulation. Furthermore, the greater alterations in VO2 than in HRV may be related to short-term APT.

Baixos níveis de benziladenina (BAP), baixo potencial de água no meio e baixa umidade condicionada por tampas de algodão foram capazes de inibir a vitrificação de cravo (Dianthus caryophyllus L.) cultivado In vitro, mas essas condições implicaram no baixo desenvolvimento das plantas e da taxa de propagação. Elevados níveis de NH4NO3 demonstraram serem altamente promotores da vitrifícação assinalada pelo alto conteúdo de proteína, enquanto relação inversa foi constatada para altos níveis de CaCl2, aos quais seguiu-se aumento na atividade da peroxidase. Os resultados permitiram estabelecer um protocolo para controle da vitrificação do cravo, constituído de 4,0 g/1 de "Gelrite", 0,5 mg/1 de ácido naftalenoacético (ANA), 0,05 mg/1 de BAP, doses normais das soluções salinas do meio MS e vedação do tipo tampas de algodão para cultivo de ápices meristemáticos. Para a fase de multiplicação, este protocolo deve ser alterado para 0,5 mg/1 de BAP, 10,3 mM de NH4NO3 e 12,0 mM de CaCl2.

Low levels of benzyl adenine (BAP), low water potential of the growth medium and low humidity due to cotton covers, inhibited vitrification of carnation (Dianthus caryophyllus L.) in vitro. However, under these conditions, a low development of plants and a decrease in the multiplication ratio, were observed. High levels of amonium nitrate enhanced vitrification with an increase in the total soluble protein content. An inverse correlation was observed in the presence of high levels of calcium chloride. The latter was correlated to an increase in peroxidase activity. The results allowed the establishment of a protocol to control vitrification during carnation meristein growth, as follows: "Gelrite", 4 g/1; naphtalene acetic acid, 0.5 mg/l; BAP, 0.05 mg/l; normal dosis of MS salts; cotton covers. For in vitro multiplication the protocol should be altered to BAP, 0.5 mg/1; amoniuin nitrate 10.3 mM; calcium chloride 12.0 mM.