Failed Stabilization for Long-Term Potentiation in the Auditory Cortex of Fmr1 Knockout Mice

Fragile X syndrome is a developmental disorder that affects sensory systems. A null mutation of the Fragile X Mental Retardation protein 1 (Fmr1) gene in mice has varied effects on developmental plasticity in different sensory systems, including normal barrel cortical plasticity, altered ocular dominance plasticity and grossly impaired auditory frequency map plasticity. The mutation also has different effects on long-term synaptic plasticity in somatosensory and visual cortical neurons, providing insights on how it may differentially affect the sensory systems. Here we present evidence that long-term potentiation (LTP) is impaired in the developing auditory cortex of the Fmr1 knockout (KO) mice. This impairment of synaptic plasticity is consistent with impaired frequency map plasticity in the Fmr1 KO mouse. Together, these results suggest a potential role of LTP in sensory map plasticity during early sensory development.     

The combination of photogrammetry and finite elements for a fine grained functional analysis of anatomical structures

Summary A new method of functional morphological analysis is presented. Combining stereophotogrammetry with the finite element technique, a new approach, permits a three-dimensional numerical stress analysis of arbitrarily shaped bodies to be performed. The stereophotogrammetric method which originated for three-dimensional calculations in the study of surfaces in land surveying is well suited for the determination of the nodal co-ordinates required for the finite element method, an engineering technique developed for behavioural analysis of solids and fluids responding to external forces. This approach was tested in a study of the functional morphology of the bill of an African wading bird, the shoebill Balaeniceps rex. A few findings of that study are given here in order to demonstrate the method. Advantages of the finite element method compared with other techniques for stress analysis of anatomical structures are also discussed. The method presents exciting possibilities for predicting displacement and stress responses more accurately and in much greater detail. The scope of this powerful computerized stress analysis technique is greatly enhanced with the introduction of stereophotogrammetry for determining the three-dimensional co-ordinates of complex anatomical structures. With the finite element method, the properties of the bone structure can be modelled as they occur in the life of the animal. This is not possible with physical models. Furthermore, rare specimens can be analysed non-destructively.     

Hydroperoxide inactivation of enzymes within spores of Bacillus megaterium ATCC19213

Abstract Hydroperoxide inactivation of the protoplast enzymes enolase, aldolase and glucose-6-phosphate dehydrogenase in intact spores of Bacillus megaterium ATCC19213 was assessed by first treating the cells with lethal levels of H₂O₂, then germinating them in the presence of chloramphenicol prior to permeabilization and enzyme assays. Glucose-6-phosphate dehydrogenase proved to be more sensitive to H₂O₂than enolase or aldolase, in agreement with findings for isolated enzymes. Average D values (time for 90% inactivation) for spores treated with 0.50% H₂O₂ were 173 min for enolase, 67 min for aldolase and 32 min for glucose-6-phosphate dehydrogenase, compared with a D value of 34 min for spore killing. H₂O₂ killing of spores was found to be conditional in that recoveries of survivors were greater on complex medium than on minimal medium. Overall, it appeared that oxidative inactivation of enzymes may be important for hydroperoxide killing of spores.     

An inquiry into the selective protection of glycine during the radiolysis of glycine-alanine mixtures in aqueous solutions and its implications to the preservation of optically active amino acids in the early earth

Akaboshi et al. (1990) has found an unexpected protection of the achiral amino acid, glycine, towards ionizing radiation at the expense of the selective destruction of the chiral amino acids, alanine and aspartic acid. The present work examines the mechanism of this protection for the case of alanine. We have developed a computer model for the radiolysis of glycine, alanine and glycine-alanine mixtures in aqueous solution. It is established that this protection is due in part to the reaction of the α-radical of glycine with alanine to regenerate a more stable α-radical, according to the following reaction, $$ \cdot CH(NH_3^ + )CO_2^ - + CH_3 CH(NH_3^ + )CO_2^ - \to CH_2 (NH_3^ + )CO_2^ - + CH_3 \dot C(NH_3^ + )CO_2^ -$$ The rate constant of this reaction was estimated to be ≤10⁴M^-1s^-1. The implications for this selective protection of glycine are considered for a hypothetical case in which there would be an enrichment of about 10% ofL-alanine in the primitive ocean and taking the glycine/alanine ratios obtained in CH₄-and CO₂- dominated atmospheres using electric discharge experiments. It is predicted that alanine would be rapidly destroyed and radioracemized in spite of the fact that the concentration of alanine is equal or significantly lower than that of glycine. Assuming that chiral amino acids were a prerequisite for the origin of life, it can be deduced that life could have appeared in a relatively short period of time unless there was a constant supply of optical amino acids from extraterrestrial sources.     

Molecular characterization of the proteinase-encoding gene, prb1, related to mycoparasitism by Trichoderma harzianum

The soil fungus Trichoderma harzianum is a mycoparasitic fungus known for its use as a biocontrol agent of phytopathogenic fungi. Among other factors, Trichoderma produces a series of antibiotics and fungal cell wall-degrading enzymes. These enzymes are believed to play an important role in mycoparasitism. Among the hydrolytic enzymes, we have identified a basic proteinase (Prb1) which is induced by either autoclaved mycelia, fungal cell wall preparation or chitin; however, the induction does not occur in the presence of glucose. The proteinase was purified and biochemically characterized as a serine proteinase of 31 kDa and pl 9.2. Based on the sequence of three internal peptides, synthetic oligonudeotide probes were designed. These probes allowed subsequent isolation of a cDNA and its corresponding genomic clone. The deduced amino acid sequence indicates that the proteinase is synthesized as a pre-proenzyme and allows its classification as a serine proteinase. Northen analysis shows that the induction of this enzyme is due to an increase in the corresponding mRNA level.     

Heterostyly in the Canarian endemic Jasminum odoratissimum (Oleaceae)

Jasminum odoratissimum is a Madeira and Canary Islands endemic showing classic heterostyly, i.e. with long-styled flowers with anthers at a low level in the corolla tube and short-styled flowers with anthers at a high level in the corolla tube. Short-styled flowers have large pollen, whereas long-styled flowers have small pollen. The two types are present in equal frequencies in the population.     

Allozymic characterization and evolutionary relationships in the BrazilianAkodon cursor species group (Rodentia-Cricetidae)

The present study involved an electrophoretic survey of 22 protein loci in 269 individuals belonging to three species of the genusAkodon, A. aff.cursor (2n=16),A. cursor (2n=14/15), andA. montensis (2n=24/25/26), collected in Eastern Brazil. The joint results of gene diversity, genetic distances, phenetic analyses, and phylogenetic trees suggested thatA. aff.cursor has recently separated fromA. cursor and that the three species have experienced a recent chromosomal divergence followed by low allozyme differentiation. These data are in agreement with their classification as sibling species.     

Generation of anNco I restriction site for translational fusions using PCR-mediated,site-directed mutagenesis

A polymerase chain reaction-based method of site-directed mutagenesis was used to introduce anNco I restriction site on the translation start site of a tomato peroxidase gene. This quick and efficient method utilized two overlapping synthetic oligonucleotide primers containing the requisite base pair changes on the ATG translation start site and two flanking primers in PCR. The resulting DNA amplified fragments were fused together byNco I digestion at the mutated ends followed by a T4 ligation reaction. A rapid alternative method utilizing the overlapping fragments and the flanking primers in PCR can also be used for ligating the two fragments. Cloning and sequencing of the PCR-amplified fragments provided additional evidence for the presence of the site-specific mutations. Unique restriction sites upstream and downstream of the site-specific mutation allows for the easy transfer of this mutated region into the wild type peroxidase gene.