Efectos del cloruro de cloro colina y el paclobutrazol sobre el crecimiento de plantas y la calidad de raíces tuberosas de mandioca (Manihot esculenta Crantz cv. Rocha)

The effects of chlorocholine chloride (CCC) and paclobutrazol (PBZ) foliar application on shoot and root parameters of cassava field-grown plants were studied (0, 45 and 90 mg active ingredient per plant). CCC and PBZ reduced total plant and first branch height, aerial fresh mass and tuberous root number. PBZ delayed branching and significantly decreased tuberous root fresh mass, while CCC caused no modifications in these parameters. In addition, CCC and PBZ treatments did not modify tuberous root diameter, while PBZ reduced tuberous root length significantly. Starch content was increased by both growth regulators at the lower dose, whereas dry matter content was increased only by CCC. In conclusion, CCC suppresses excessive vegetative growth, favours quality attributes and does not alter yield, hence improving harvest index. Although PBZ at a low dose increases the starch content and harvest index, its effects on other parameters are undesirable.Fil: Medina, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Burgos, A.. Universidad Nacional del Nordeste; ArgentinaFil: Difranco, V.. Universidad Nacional del Nordeste; ArgentinaFil: Mroginski, Luis Amado. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Cenóz, P.. Universidad Nacional del Nordeste; Argentin

Evaluación de la calidad comercial de tres clones de mandioca (Manihot esculenta, crantz) en tres épocas de cosecha

La calidad comercial de las raíces de mandioca, tiene como indicadores los contenidos de: ácido cianhídrico, humedad, materia seca, almidón, fibra, tiempo de deterioro poscosecha y comportamiento en la cocción. En el Nordeste Argentino la cosecha se efectúa desde marzo hasta agosto, sin embargo la calidad de las raíces no es la misma al principio, que al final de dicho periodo. El objetivo del presente trabajo fue evaluar diferentes componentes de calidad en tres épocas de cosecha para tres clones comerciales de la zona. Se probaron los clones: Cambí, alomita y Catiguá, cosechados en: abril, mayo y junio, en un diseño totalmente al azar con 5 repeticiones. Se analizaron: almidón, ácido cianhídrico, fibra, humedad, materia seca y deterioro poscosecha, realizándose Análisis de Variancia y "test" de Tukey en cada cosecha y el método de Kruskal-Wallis para el deterioro, a cuatro y siete días de la cosecha Cambi presentó mayor porcentaje de ácido cianhídrico y fibra y menor porcentaje de almidón y materia seca. Palomita presentó menor porcentaje de materia seca que Catiguá, aunque no se diferenciaron en el porcentaje de almidón y ácido cianhídrico. A través de las cosechas: Cambí no modificó su porcentaje de almidón ni ácido cianhídrico, y aumentó el porciento de materia seca. Palomita no modificó el porcentaje de ácido cianhídrico, e incrementó el porciento de almidón y materia seca. Catiguá aumentó el ácido cianhídrico y materia seca y disminuyó almidón. Los clones Cambí y Catiguá presentaron características de calidad más destacados pero en cosecha intermedia (Mayo), en tanto Palomita se comportó mejor en cosecha temprana (Abril). El deterioro aumentó con los días poscosecha, presentando Catiguá en los momentos indicados el mayor deterioro y Palomita el menor

Species-Specific Diversity of a Fixed Motor Pattern: The Electric Organ Discharge of Gymnotus

Understanding fixed motor pattern diversity across related species provides a window for exploring the evolution of their underlying neural mechanisms. The electric organ discharges of weakly electric fishes offer several advantages as paradigmatic models for investigating how a neural decision is transformed into a spatiotemporal pattern of action. Here, we compared the far fields, the near fields and the electromotive force patterns generated by three species of the pulse generating New World gymnotiform genus Gymnotus. We found a common pattern in electromotive force, with the far field and near field diversity determined by variations in amplitude, duration, and the degree of synchronization of the different components of the electric organ discharges. While the rostral regions of the three species generate similar profiles of electromotive force and local fields, most of the species-specific differences are generated in the main body and tail regions of the fish. This causes that the waveform of the field is highly site dependant in all the studied species. These findings support a hypothesis of the relative separation of the electrolocation and communication carriers. The presence of early head negative waves in the rostral region, a species-dependent early positive wave at the caudal region, and the different relationship between the late negative peak and the main positive peak suggest three points of lability in the evolution of the electrogenic system: a) the variously timed neuronal inputs to different groups of electrocytes; b) the appearance of both rostrally and caudally innervated electrocytes, and c) changes in the responsiveness of the electrocyte membrane

Glutamate, GABA and Acetylcholine Signaling Components in the Lamina of the Drosophila Visual System

Synaptic connections of neurons in the Drosophila lamina, the most peripheral synaptic region of the visual system, have been comprehensively described. Although the lamina has been used extensively as a model for the development and plasticity of synaptic connections, the neurotransmitters in these circuits are still poorly known. Thus, to unravel possible neurotransmitter circuits in the lamina of Drosophila we combined Gal4 driven green fluorescent protein in specific lamina neurons with antisera to γ-aminobutyric acid (GABA), glutamic acid decarboxylase, a GABAB type of receptor, L-glutamate, a vesicular glutamate transporter (vGluT), ionotropic and metabotropic glutamate receptors, choline acetyltransferase and a vesicular acetylcholine transporter. We suggest that acetylcholine may be used as a neurotransmitter in both L4 monopolar neurons and a previously unreported type of wide-field tangential neuron (Cha-Tan). GABA is the likely transmitter of centrifugal neurons C2 and C3 and GABAB receptor immunoreactivity is seen on these neurons as well as the Cha-Tan neurons. Based on an rdl-Gal4 line, the ionotropic GABAA receptor subunit RDL may be expressed by L4 neurons and a type of tangential neuron (rdl-Tan). Strong vGluT immunoreactivity was detected in α-processes of amacrine neurons and possibly in the large monopolar neurons L1 and L2. These neurons also express glutamate-like immunoreactivity. However, antisera to ionotropic and metabotropic glutamate receptors did not produce distinct immunosignals in the lamina. In summary, this paper describes novel features of two distinct types of tangential neurons in the Drosophila lamina and assigns putative neurotransmitters and some receptors to a few identified neuron types

Vergleichende morphologische und histologische untersuchungen am geruchsorgan der knochenfische

1. Untersucht wurden 18 Knochenfischarten aus 13 Familien.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47539/1/435_2004_Article_BF00429940.pd

Effects of chlorocholine chloride and paclobutrazol on cassava (Manihot esculenta Crantz cv. Rocha) plant growth and tuberous root quality

Se estudiaron los efectos de la aplicación foliar del cloruro de cloro colina (CCC) y del paclobutrazol (PBZ) sobre parámetros de crecimiento aéreo y radical de plantas de mandioca cultivadas a campo (0,45 y 90 mg de principio activo por planta). El CCC y el PBZ redujeron la altura total de las plantas y la altura de la primera ramificación, el peso fresco de los órganos aéreos y el número de raíces tuberosas por planta. El PBZ retrasó la ocurrencia de la ramificación y causó reducciones significativas del peso fresco de las raíces tuberosas, mientras que el CCC no afectó dichos parámetros. Los tratamientos con CCC y PBZ no modificaron el diámetro de las raíces tuberosas, aunque el PBZ redujo significativamente su longitud. El contenido de almidón de raíces tuberosas se incrementó por la aplicación de ambos reguladores del crecimiento en su dosis mínima; sin embargo, el contenido de materia seca deestas sólo fue aumentado por el tratamiento con CCC. En conclusión, el CCC evita el crecimiento vegetativo excesivo, favorece los atributos de calidad deraíces tuberosas sin afectar el rendimiento y mejora el índice de cosecha. Sibien el PBZ en bajas concentraciones incrementa el contenido de almidón delas raíces tuberosas y el índice de cosecha, sus efectos sobre otros parámetrosson indeseables

Biotechnology applied to cassava propagation in Argentina

Cassava is a staple food to millions of people in tropical and subtropical countries. Although it is traditionally cultivated from stem cuttings, which is a simple and inexpensive technique, this method presents serious problems such as low multiplication rates, difficulties to conserve stems, and dissemination of pests and diseases. Many of these problems would be solved through in vitro tissue culture. In this work, we evaluated the in vitro establishment and multiplication of 28 cassava clones of agronomic interest for the Northeastern Argentina, a boundary area for this crop. Since the transfer of in vitro plants to ex vitro conditions is a critical phase of micropropagation, we evaluated the effect of different acclimatization treatments on survival and growth parameters of plants (cv EC118) grown in a culture chamber. We also scored their field survival and performance by comparing them with plants obtained by the conventional planting technique. After disinfection, uninodal segment culture in Murashige and Skoog medium supplemented with 0.01 mg/L BAP + 0.01 mg/L NAA + 0.1 mg/L GA3 allowed the in vitro establishment of 100% of the clones and their subsequent multiplication. Cultures were maintained at 27º±2ºC with a 14 h photoperiod. During establishment, sprouting occurred in 100% of the clones and rooting in 93% of them; the remaining clones formed roots during the multiplication phase. Thirty days after multiplication, the plants presented significant differences in plant height, average number of nodes per plant and number of roots per plant. During acclimatization, five treatments were evaluated: three substrates (perlite, T1; sand + vermicompost, T2; commercial substrate composed of peat and perlite, T3), and two hydroponic treatments (tapwater, T4; Arnon and Hoagland nutrient solution, T5). Although in chamber growth conditions the acclimatized plants showed statistical differences in several growth parameters depending on the treatments, no differences were observed in the survival percentage. Shoot and root fresh and dry weight and leaf area were highest in T5 and lowest in T2 and T4. Field survival differed significantly between treatments, discriminating a group with high survival rates (T5: 73.3%, T3: 86.7%, and control treatment: 100%) and another with low survival rates (T2: 33.3%; T1: 35% and T4: 36.7%). At harvest, there were no significant differences in the total fresh weight. However, the percentage of biomass partitioned to roots was significantly higher in T3 and T5, which resulted in a higher tuberous roots yield than that of the control treatment.Fil: Cavallero, M.. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Chaco-formosa. Estacion Experimental Agropecuaria El Colorado. Agencia de Extension Rural El Colorado.; ArgentinaFil: Medina, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Hoyos, R.. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Chaco-formosa. Estacion Experimental Agropecuaria El Colorado. Agencia de Extension Rural El Colorado.; ArgentinaFil: Cenóz, P.. Universidad Nacional del Nordeste; ArgentinaFil: Mroginski, Luis Amado. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentin