Molecular pharmacological dissection of short- and long-term memory

1. It has been discussed for over 100 years whether short-term memory (STM) is separate from, or just an early phase of, long-term memory (LTM). The only way to solve this dilemma is to find out at least one treatment that blocks STM while keeping LTM intact for the same task in the same animal.2. The effect of a large number of treatments infused into the hippocampus, amygdala, and entorhinal, posterior parietal or prefrontal cortex on STM and LTM of a one-trial step-down inhibitory avoidance task was studied. The animals were tested at 1.5 h for STM, and again at 24 h for LTM. The treatments were given after training.3. Eleven different treatments blocked STM without affecting LTM. Eighteen treatments affected the two memory types differentially, either blocking or enhancing LTM alone. Thus, STM is separate from, and parallel to the first hours of processing of, LTM of that task.4. The mechanisms of STM are different from those of LTM. The former do not include gene expression or protein synthesis; the latter include a double peak of cAMP-dependent protein kinase activity, accompanied by the phosphorylation of CREB, and both gene expression and protein synthesis.5. Possible cellular and molecular events that do not require mRNA or protein synthesis should account for STM. These might include a hyperactivation of glutamate AMPA receptors, ribosome changes, or the exocytosis of glycoproteins that participate in cell addition.     

The importance of microscopic examination in the management of desquamative diseases of the scalp

After determining the usual malassezic biota of the scalp in adult, normal persons, 259 patients with different desquamative diseases were studied by a simple adhesive tape technique. The main purpose of this study was to investigate the utility of this technique to improve the diagnosis and treatment of patients. Most patients with seborrhoeic dermatitis and sebopsoriasis demonstrated large numbers of {it Malassezia} spp. cells corresponding to the so called ``pityrosporosis'. Only 43.6% of patients with pityriasis capitis (dandruff) presented with such a diagnosis. Symptomatic pityrosporosis of the scalp should be treated with imidazolic derivatives or other antifungal substances. Patients with psoriasis of the scalp showed a typical microscopic picture represented by parakeratosic (nucleated) keratinocytes with absence of lipophilic yeasts which should be attributed to the usual dryness of the scales .Microbial epidermitis (eczema) of the scalp revealed another characteristic picture constituted by abundant leukocytes and bacteria without the presence of yeasts. The different microscopic pictures seen with this simple technique for diseases of the scalp, offer an adjunct to make a proper diagnosis and to establish a convenient treatment in cases which are not clinically well defined. This revised version was published online in June 2006 with corrections to the Cover Date.     

Evaluation of the impact of Bacillus thuringiensis serovar israelensis and Temephos,used for the control of Simulium (Chirostilbia) pertinax Kollar, 1832 (Diptera,Simuliidae) on the associated entomofauna,Paraty, state of Rio de Janeiro,Brazil

The study was set up to evaluate the impact of two commercial larvicide formulations, Bacillus thuringiensis serovar israelensis base (Bti) at 15 ppm/1 min and temephos at 0.03 ppm of active ingredient, used to control Simulium pertinax populations, on associated non-target entomofauna occupying the same breeding sites. The experiments were carried out on the Pedra Branca and Muricana rivers, on the slopes of Serra do Mar massif, municipality of Paraty, state of Rio de Janeiro, Brazil. Bti was applied to the river Pedra Branca and temephosto theriver Muricana. On both rivers, treatment and control sections were labeled as such, each one with two observation posts: slow moving water and fast water regions respectively. Artificial substrata was used to evaluate the abundance of associated entomofauna. Attached immature stages of arthropods were removed from both of its surfaces fortnightly. Were collected, from the two rivers, 28 477 specimens of the entomofauna associated with S. pertinax. The families Hydropsychidae, Chironomidae, Bactidae, Simuliidae, Blephariceridae and Megapodagrionidae were represented. These was an impact of temephos on the entomofauna associated with S. pertinax only in Simuliidae and Chironomidae, and to Bti only in Simuliidae. However, the reduction in their numbers was not statistically significant.     

Chromosomal polymorphism,syntenic relationships,and ploidy in the pathogenic fungus Paracoccidioides brasiliensis

Pulsed field gel electrophoresis (PFGE) and DNA hybridization were used to establish and compare the electrophoretic karyotypes of 12 clinical and environmental Paracoccidioides brasiliensis isolates from different geographic areas. Gene mapping allowed the identification of synteny groups and the use of isolated whole chromosomal bands to probe chromoblots indicated the existence of repetitive sequences, contributing to a better understanding of the structure and organization of the fungus genome. This represents the first comparative mapping study among different isolates. The results are indicative of the existence of genetic differences among natural isolates. DNA content of DAPI-stained nuclei of each isolate was estimated by confocal microscopy. Comparison of the genome sizes estimated by PFGE with those calculated by microfluorometry indicated the possible existence of haploid and diploid (or aneuploid) isolates of the fungus.     

Immunolocalization of proacrosin/acrosin in bovine sperm and sperm penetration through the zona pellucida

The aim of the present work was to immunolocalize acrosin in bull spermatozoa incubated for up to 6 h in capacitating culture medium (TALP-heparin), in order to study the kinetics of its release during the acrosome reaction and in vitro sperm penetration. Six replicates from semen of one bull were used. Acrosin was localized by the silver-enhanced immunogold technique using anti-bovine acrosin monoclonal antibody ACRO-C2E5. Spermatozoa thus showed the presence of acrosin only at the acrosomal region. Four different patterns were seen: (1) no labeling: (2) intense labeling on the rim of the portion of the acrosome; (3) diffuse label over the entire acrosomal region; and (4) intense label over the entire acrosomal region. Spermatozoa incubated in capacitating medium for 4 h showed that unlabeled (pattern 1) spermatozoa decreased from 72% to 28% difference that was found to be significant (p<0.05). Patterns 3 and 4 increased from about 10% to 20-29%, (p<0.05). With further incubation (4-6 h), pattern 1 increased while patterns 3 and 4 decreased differences were not significant (p0.05). The incidence of pattern 2 did not change through the whole incubation period. Sperm penetration through the zona pellucida of in vitro matured bovine oocytes (57%) or empty zonae pellucida (70.5%) increased (p<0.05) as a function of sperm incubation time in capacitating medium. The presence of acrosin, as determined by the silver-enhanced immunogold technique, was highly correlated with sperm penetration of in vitro mature bovine oocyte (r=0.98) and cryopreserved zonae pellucidae (r=0.93) (p<0.01).     

Characterization of constitutive heterochromatin of Callithrix geoffroyi (Callitrichidae, Primates) by restriction enzymes and fluorochrome bands

The neotropical primate genus Callithrix comprises two groups of species, jacchus and argentata, which inhabit distinct geographical regions and manifest different fur coloration and constitutive heterochromatin (CH) markers in their karyotypes. In this investigation the CH of a representative of the jacchus group, Callithrix geoffroyi, was analysed using fluorochromes and restriction enzymes in situ. To clarify the source of the constitutive heterochromatin of both groups, the data obtained in the jacchus group were compared with those published in the argentata group obtained by the same techniques. The C-bands of C. geoffroyi (four specimens, 2n = 46) were centromeric in all chromosomes, and distally located in pairs 6 and 22. The Alu I, Hae III, Hin fI, Rsa I, Dde I, Mbo I, and Msp I restriction endonucleases and CMA3 and DAPI fluorochromes produced different bands, which allowed the characterization of four distinct types of constitutive heterochromatin in the C. geoffroyi genome. Several of these types of heterochromatin were present in the ancestor of the two groups of species, jacchus and argentata, while others originated after their cladogenesis.     

Preparation of sucrose heptaesters unsubstituted at the C-1 hydroxy group of the fructose moiety via selective O-desilylation

Selective O-desilylation of 6,1',6'-tri-O-tert-butyldiphenylsilyl-2,3,4,3',4'-penta-O-benzo ylsucrose with hydrofluoric acid in acetonitrile led to the 1'-O-tert-butyldiphenylsilyl derivative (96% yield), which was further perbenzoylated and deprotected at OH-1' with tetrabutylammonium fluoride (86%). An analogous sequence with the corresponding O-acetylated sucrose derivative and tetrabutylammonium fluoride as desilylating agent resulted in a lower yield of the C-1' hydroxy derivative.     

Structural differences between the repertoires of mouse and human germline genes and their evolutionary implications

 Although human and mouse antibodies are similar when one considers their diversification strategies, they differ in the extent to which kappa and lambda light chains are present in their respective variable light chain repertoires. While the Igk-V germline genes are preponderant in mice (95% or more), they comprise only 60% in humans. This may account for differences in the structural repertoire encoded in the Igk-V germline genes of these species. However, this subject has not been properly investigated, partially because a systematic structural characterization of the mouse Igk-V germline genes has not been undertaken. In the present study we compiled all available information on mouse Igk-V germline genes to characterize their structural repertoire. As expected, comparison with the structural repertoire of human Igk-V germline genes indicates differences. The most interesting is that the mouse Igk-V germline gene repertoire is more diverse in structural terms than its human counterpart: the mouse encodes seven canonical structure classes (combination of canonical structures in L1 and L3). In contrast, the human encodes only four. Analysis of the evolutionary relationships of human and mouse Igk-V germline genes led us to propose that the difference reflects a strategy of mice to compensate for the small lambda chain contribution to the repertoire of their variable light chains. Received: 1 June 1997 / Revised: 6 October 1997