Immunocytochemical characterisation of endophytic bacteriaAzospirillum brasilense, Herbaspirillum seropedicae, Burkholderia ambifaria andGluconacetobacter diazotrophicus

In the present work an immunocytochemical characterisation of four endophytic bacterial species has been made by using polyclonal antiserum produced against each of the four bacterial strains previously heated at 60 °C. The aim of this researchsito identify common elements among bacteria associated with their endophytic behaviour. Analysis of extracts of each strain by immunoblotting and ELISA confirmed the presence of proteins from different bacterial strains made up of common epitopes. However, antisaproduced againstHerbaspirillum seropedicae andBurkholderia ambifaria show a high number of bands recognised on each extracts, while antisera againstAzospirillum brasilense andGluconacetobacter diazotrophicus show a low number of bands recognised on each extract. Immunogold labelling showed that epitopes are located both on the cell wall and in the cytoplasm; most likely they could be preursor cell wall proteins synthesized inside the cytoplasm and subsequently transported onto cell wall. Finally, the common bands amog bacterial strains revealed by immunoblotting could play a role as active hydrolases involved in host tissue penetration.     

Chlorpromazine as permeabilizer and reagent for detection of microbial peroxidase and peroxidaselike activities

Chlorpromazine was used to perform a test for the detection of microbial peroxidase activities. The compound acts as both a cell permeabilizer and a reagent in the procedure developed which allows the detection of peroxidase and peroxidase like reactions both semiquantitatively in whole cell determinations and quantitatively in cell-free supernatants.     

Polyamine metabolism in hants : Arginine and omithine decarboxylase activity in ripeningTrlticum durum seeds

The pattern of the activity of arginine decarboxylase (ADC) and omithine decarboxylase (ODC) involved in polyamine synthesis in ripening wheat seeds was examined. The aim was to study the polyamines and the activity of the two enzymes in correlation with the growth processes occurring in the developing wheat seeds. The results obtained showed a very different pattern of polyamine content in the two organs of caryopsis, and that the two enzymes in the embryos have a higher activity than in the endosperms. Moreover, while in the embryos the ADC exhibits higher activity than the ODC, in the endosperms the activity of ODC is about similar to that of ADC. This pattern is discussed in relation to the different histological characteristics of embryo and endosperm tissues during seed development.     

Superoxide dismutase in vegetative cells, heterocysts and akinetes of Anabaena cylindrica Lemm

Abstract: Superoxide dismutase (SOD) activity was assayed in vegetative cells, heterocysts and akinetes of Anabaena cylindrica Lemm. The iron-containing isoenzyme (Fe-SOD) was in all cases predominant over the manganese-containing isoenzyme (Mn-SOD). Differentiated cells maintained the same relative content of the two enzymes as in vegetative cells. However, heterocysts and akinetes contained only 20 and 35%, respectively, of the total SOD activity present in vegetative cells.
Both Mn-SOD and Fe-SOD activities increased in all types of cells isolated from A. cylindrica grown at high light intensity. The increase of SOD in heterocysts paralleled that of nitrogenase, suggesting a role of SOD in the protection mechanism of nitrogenase.     

Adaptability of the Gompertz equation to the growth kinetics of a transplantable experimental tumor

We have carried out a study on the growth kinetics of a solid rat reticulosarcoma, by making use of the Gompertz equation. This approach is not sufficiently valid for the groups as a whole, but furnishes useful information when applied to individual tumors. In fact the values for relative (1/V dV/dt) and absolute (dV/dt) velocities calculated for individual tumors by making use of this equation, exhibit greater significance and consistency with respect to tumor-host integration.     

Sub-cellular Localization of Calcium in Azolla-Anabaena Symbiosis by Chlortetracycline,ESI and EELS

The subcellular localization of calcium in cells of symbiotic partners located within leaf cavities of Azolla was investigated by using chlorotetracycline, ESI and EELS analysis. Loosely membrane-bound calcium was evidenced by using CTC or EGTA and CTC, in cytoplasmic regions of Azolla hair cells and in cytoplasm of the cyanobiont. Tightly membrane-bound calcium revealed by CTC, and ESI and EELS analysis, was observed in cyanophycin granules and carboxysomes of the cyanobiont. A third calcium type, revealed by ESI and EELS analysis, was localized at the level of cell walls of simple and branched Azolla hairs, in the envelope of heterocysts, and in the cell walls of the cyanobiont.     

A study on pollen grains ofCrocus cartwrightianus (Iridaceae)

Crocus cartwrightianus andC. cartwrightianus cv.albus pollen have been studied from structural and ultrastructural points of view and the germination assayed in vivo and in vitro.C. cartwrightianus pollen is regularly shaped and sized, has a low percentage of anomalous grains and has a high germination rate in vitro, whileC. cartwrightianus cv.albus is less regularly shaped with some variation in size and has a high percentage of anomalous grains and a low germination percentage in vitro. Ultrastructural observations have revealed, in the pollen of both the taxa, the presence of a thin elongated vegetative nucleus and a generative cell surrounded by a thin membrane. However,C. cartwrightianus pollen shows a thicker intine, andC. cartwrightianus cv.albus shows numerous pollen germination anomalies which are in common withC. sativus.     

Role of serum on cryopreservation and subsequent viability of mouse bone marrow hemopoietic stem cells

Normal mouse marrow cells were frozen in an automatically controlled freezer at a cooling rate of 1 °C/min to ?40 °C and 7 °C/ min to ?100 °C using dimethylsulfoxide as a cryoprotective agent. The freezing solution contained in addition either 10% homologous serum or 10% fetal calf serum. Control samples were frozen with serum-free medium. After thawing, stepwise dilution, and washing, the cells were counted, checked for CFU-s content, and cultured in Millipore diffusion chambers for 2 and 7 days.HS resulted in a recovery of 59.7% nucleated cells and 100.5% CFU-s whereas FCS and serum-free medium resulted in 59.8 and 34.7% nucleated cells and 24.5 and 18.2% CFU-s, respectively. After 2 days of culture, D.C. data showed a correlation with the CFU-s results. After 7 days of culture, no significant difference was observed between the three groups. The results of these experiments indicate that HS is required for an optimal stem cell cryopreservation and that a 2-day D.C. culture is a reliable assay system for transplantable hemopoietic tissue.     

Characterization of [3H]Dopamine Uptake Sites and [3H]Cocaine Recognition Sites in Primary Cultures of Mesencephalic Neurons During In Vitro Development

[3H]Dopamine uptake and [3H]cocaine binding sites were studied in primary cultures of ventral mesencephalon from 14-day-old rat embryos. Specific binding sites for [3H]cocaine and [3H]mazindol were detected only in intact cell cultures of ventral mesencephalon, and were absent in sonicated, washed membranes prepared from these cell cultures. [3H]Cocaine was not taken up by the cells through an active transport process because [3H]cocaine binding occurred also at 4 degrees C. Moreover, the possibility of [3H]cocaine entering the cells by passive diffusion and ion trapping was also excluded because extensive washing failed to remove [3H]cocaine from the cells. [3H]Cocaine binding was reduced to 6% of control when cells were permeabilized with streptolysin O (0.2 U/ml, 5 min). Taken together, these results suggest that in cultured mesencephalic neurons, [3H]cocaine may enter the cell by passive diffusion and then be sequestered by a cytosolic compartment that is lost in the process of permeabilization or sonication and washing of membrane preparations. Permeabilization of cultured neurons failed to alter the storage of [3H]dopamine. When cells were permeabilized with streptolysin O (0.2 U/ml; 5 min) after [3H]dopamine was taken up, [3H]dopamine was retained by the cells and did not leak into the incubation medium, indicating that [3H]dopamine was stored in sites that could not pass through the perforated membranes. In contrast, [3H]dopamine uptake into already permeabilized cells was reduced by 33%, suggesting that a cytosolic protein that had leaked out may play a functional role in the uptake process. In contrast to striatal membrane preparations of adult rats, [3H]cocaine binding in intact mesencephalic cell cultures was Na+ independent.(ABSTRACT TRUNCATED AT 250 WORDS)     

Non-enzymatic and microsome-dependent binding of polycyclic hydrocarbons to DNA and polynucleotides

The binding of tritium-labelled 7,12-dimethylbenz[a]anthracene (DMBA), benzo[a]pyrene (BP) and 3-methylcholanthrene (MCA) to DNA or polynucleotides in vitro was re-examined both in the presence and in the absence of rat liver or human placental microsomes.A high level of non-enzymatic binding was evident when thymus DNA was used as acceptor. This non-enzymatic binding made it difficult to determine the effect of microsomes, except in the case of BP when induced rat microsomes were used. Better results were obtained using polynucleotides: a definite microsome-dependent binding occurred between all the polynucleotides and all the hydrocarbons tested.No clear evidence of binding catalysed by microsomes from human placenta was found except in polynucleotide-BP interactions: further studies are required to completely evaluate the ability of such nucleic acid-microsomal system for testing in vitro possible oncogenic substances in animals and humans.