LEONOR M.E. ITUARTE*, TERESA B. VIERA*, TEOBALDO A. SALDEÑA*, JUAN C. DE ROSAS**, MABEL FÓSCOLO**, JORGE E. IBÁÑEZ*, FERNANDO D. SARAVÍ*

BIOCELL, Vol.30, No.1, pp. 43-49, 2006, DOI:10.32604/biocell.2006.30.043

Abstract Electrophysiological events occur early after fertilization, along with changes in intracellular Ca²⁺ concentration . Passive electrical parameters were determined in golden hamster oocytes by whole cell patch-clamp method. In separate experiments the effect of 4-aminopyridine on resting oocytes was tested. The single-channel patch clamp configuration was employed to assess the electrical response to fertilization with homologous sperm. Structure of oocytes submitted to patch clamp was evaluated with scanning electron microscopy and found to be preserved.
Oocyte diameter was 70.2 ± 2.2 µm; their resting parameters were: membrane potential 23.8 ± 0.8 mV; total membrane specific… More >

MARÍA DE LOS A. ALVAREZ, NORA B. DEBATTISTA, NORA B. PAPPANO

BIOCELL, Vol.30, No.1, pp. 39-42, 2006, DOI:10.32604/biocell.2006.30.039

Abstract In our previous studies, bacteriostatic action of flavonoids against Staphylococcus aureus ATCC 25 923 and Escherichia coli ATCC 25 922 was demostrated. In the present work synergism of their combinations in order to improve the bacteriostatic action against the same microorganisms was determined. The experiences were made in nutritive broth, maintaining constant one drug concentration (20 µg/ml) and increasing the other one. A turbidimetric kinetic method was used and by means of a mechanism previously proposed, the minimal inhibitory concentrations (MIC´s) of each flavonoid combination were determined. The MIC´s for assayed combinations against S. aureus were: variable morin More >

MARIA CAROLINA AQUINO LUQUE, SÔNIA NAIR BÁO

BIOCELL, Vol.30, No.1, pp. 33-38, 2006, DOI:10.32604/biocell.2006.30.033

Abstract The ultrastructure of normal, ejaculated spermatozoa of Bos indicus was studied by means of electron microscopy, being evaluated in two principal parts, the head and the tail. The head is flat, oval or paddle-shaped with a square base, which provides a concave recess for the insertion of the tail. The acrosome tightly covers the anterior two thirds of the nucleus. A distinct unilateral acrosomal bulge was observed along the apical edge of the head. The equatorial region demarcates the acrosome from the post-equatorial region that covers the caudal one third of the nucleus. The classical 9+9+2 More >

ZONG-YUN LI^1,2*, MEI-LI FU¹, FANG-FANG HU¹, SHU-FENG HUANG¹, YUN-CHUN SONG²

BIOCELL, Vol.30, No.1, pp. 27-32, 2006, DOI:10.32604/biocell.2006.30.027

Abstract The ribosomal DNA (45S rDNA) behaviors during the cell cycle were analyzed on interphase nuclei, prophases, metaphases, pachytene chromosomes and extended DNA fibers in rice (Oryza,sativa ssp.indica cv.Guangluai No.4) by using high-resolution fluorescent in situ hybridization (FISH). The results show that 45S rDNA is located at the ends of short arms of chromosomes 9 and 10. But the signals are much more intense on chromosome 9 than on chromosome 10 in metaphase. Pachytene chromosome has rDNA signal arrays on chromosome 9. Different phases are described and discussed. These results indicate that the activity of rDNA at individual More >

JUAN LIN¹, XUANWEI ZHOU², JIONG FEI², ZHIHUA LIAO¹, WANG JIN¹, XIAOFEN SUN^1,*, KEXUAN TANG^1,2,*

BIOCELL, Vol.30, No.1, pp. 15-25, 2006, DOI:10.32604/biocell.2006.30.015

Abstract A gene encoding a mannose-binding lectin, Pinellia pedatisecta agglutinin (PPA), was isolated from leaves of Pinellia pedatisecta using genomic walker technology. The ppa contained an 1140-bp 5’-upstream region, a 771-bp open reading frame (ORF) and an 829-bp 3’-downstream region. The ORF encoded a precursor polypeptide of 256 amino acid residues with a 24-amino acid signal peptide. There were one putative TATA box and six possible CAAT boxes lying in the 5’-upstream region of ppa. The ppa showed significant similarity at the nucleic acid level with genes encoding mannose-binding lectins from other Araceae species such as Pinellia ternata, Arisaema heterophyllum, Colocasia esculenta More >

Hernández-Castillo¹ FD, Adalberto Aguirre-Aguirre¹, RH Lira-Saldivar², E Guerrero-Rodríguez¹, G Gallegos-Morales¹

Phyton-International Journal of Experimental Botany, Vol.75, pp. 91-101, 2006, DOI:10.32604/phyton.2006.75.091

Abstract The biological efficiency of five stocks of Bacillus subtilis, of the mixture of the bioproducts quitosan and Larrea tridentata extract, and five synthetic fungicides were evaluated against the fungus Alternaria dauci Kühn in laboratory and greenhouse experiments. The effect of these compounds on growth and yield of carrot was also determined. Stocks of the bacteria Bacillus (B3, B9, B15 and a combination of these) and the mixture quitosan- Larrea stimulated carrot development because it reached greater width, length and weight in comparison to the control and the other treatments. Stock B3 was the best in promoting carrot growth More >

Bonvissuto GL¹, CA Busso^2,*

Phyton-International Journal of Experimental Botany, Vol.75, pp. 55-70, 2006, DOI:10.32604/phyton.2006.75.055

Abstract This study was conducted in the Monte Austral Neuquino (MAN), Provincia de Neuquén, Argentina (39°20’ S; 69°19’ W). Vegetation is distributed at the site as vegetation patches. There are two contrasting sites on the soil of these patches: location 1, under the canopy of major perennial grasses and shrubs, and location 2, which includes the vegetation uncovered interspaces between the patches. The hypothesis of this work was that hydraulic lift is greater under than between the vegetation patches. Thermocouple psychrometers were placed under the shrubs and in the interspaces in each of two vegetation patches,… More >

C.P. Providakis¹

Structural Durability & Health Monitoring, Vol.2, No.4, pp. 249-254, 2006, DOI:10.3970/sdhm.2006.002.249

Abstract This paper explores the concept of strain energy density rate in relation to the crack initiation in fracture analysis problems arising in creeping cracked structural components. The analysis of the components is performed by using the boundary element methodology in association with the employment of singular boundary elements for the modeling of the crack tip region. The deformation of the material is assumed to be described by an elastic power law creep model. The strain energy density rate theory is applied to determine the direction of the crack initiation for a center cracked plate in More >

G. Davì¹, A. Milazzo¹

Structural Durability & Health Monitoring, Vol.2, No.3, pp. 177-182, 2006, DOI:10.3970/sdhm.2006.002.177

Abstract An alternative single domain boundary element formulation and its numerical implementation are presented for the analysis of two-dimensional cracked bodies. The problem is formulated employing the classical displacement boundary integral representation and a novel integral equation based on the stress or Airy's function. This integral equation written on the crack provides the relations needed to determine the problem solution in the framework of linear elastic fracture mechanics. Results are presented for typical problems in terms of stress intensity factors and they show the accuracy and efficiency of the approach. More >

V. Mallardo, C. Alessandri¹

Structural Durability & Health Monitoring, Vol.2, No.3, pp. 165-176, 2006, DOI:10.3970/sdhm.2006.002.165

Abstract The formation of cracks and their propagation in brittle materials has been intensively studied in the last years. The main difficulty is related to the theoretical and numerical possibility to follow the development of regions of highly localised strains. The nonlinear phenomenon is physically different from the one which occurs in ductile materials: it starts with a narrow fracture process zone containing a large number of distributed microcracks which could lead to the formation of macrocracks and eventually to rupture. In the present paper, a simple nonlocal damage model is coupled to the crack analysis More >