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Biomedical subjects

M A Freire

Publications and source records attributed to M A Freire.

11 recordsLinked to original sources
PubMed2004

Astrocytosis, microglia activation, oligodendrocyte degeneration, and pyknosis following acute spinal cord injury.

Glial activation and degeneration are important outcomes in the pathophysiology of acute brain and spinal cord injury (SCI). Our main goal was to investigate the pattern of glial activation and degeneration during secondary degeneration in both gray matter (GM) and white matter (WM) following SCI. Adult rats were deeply anesthetized and injected with 20 nmol of N-methyl-D-aspartate (NMDA) into the ventral horn of rat spinal cord (SC) on T7. Animals were perfused after survival times of 1, 3, and 7 days. Ten-micrometer sections were submitted to immunocytochemistry for activated macrophages/microglia, astrocytes, oligodendrocytes, and myelin. Astrocyte activation was more intense in the vacuolated white matter than in gray matter and was first noticed in this former region. Microglial activation was more intense in the gray matter and was clear by 24 h following NMDA injection. Both astrocytosis and microglial activation were more intense in the later survival times. Conspicuous WM vacuolation was present mainly at the 3-day survival time and decreased by 7 days after the primary damage. Quantitative analysis revealed an increase in the number of pyknotic bodies mainly at the 7-day survival time in both ventral and lateral white matter. These pyknotic bodies were frequently found inside white matter vacuoles like for degenerating oligodendrocytes. These results suggest a differential pattern of astrocytosis and microglia activation for white and gray matter following SCI. This phenomenon can be related to the different pathological outcomes for this two SC regions following acute injury.

Animals↗
PubMed2000

The barrel field of the adult mouse SmI cortex as revealed by NADPH-diaphorase histochemistry.

The main goal of the present work was to investigate the pattern of NADPH-diaphorase activity in the somatosensory cortex of the adult mouse. Our results show that this enzyme, which is responsible for the production of the neuronal messenger nitric oxide, is abundant within the neuropil of SmI cortex, revealing the complete pattern of barrel fields. A previous study, however, had reported that NADPH-diaphorase reactivity within the barrels was transient, disappearing after the second postnatal week. We hypothesize that the massive occurrence of NADPH-diaphorase in the barrel fields of the adult mouse brain is related to the potential for plastic changes in the somatosensory cortex that is maintained throughout maturity.

Aging↗
PubMed2000

Plant lipoxygenase 2 is a translation initiation factor-4E-binding protein.

The eukaryotic initiation factor 4E (eIF4E) emerged recently as a target for different types of regulation affecting translation. In animal and yeast cells, eIF4E-binding proteins modulate the availability of eIF4E. A search for plant eIF4E-binding proteins from Arcabictopsis thaliana using the yeast genetic interaction system identified a clone encoding a lipoxygenase type 2 (AtLOX2). In vitro and in vivo biochemical assays confirm an interaction between AtLOX2 and plant eIF4E(iso) factor. A two-hybrid assay revealed that AtLOX2 is also able to interact with both wheat initiation factors 4E and 4E(iso). Deletion analysis maps the region of AtLOX2 involved in interaction with AteIF(iso)4E between amino acids 175 and 232. A sequence related to the conserved motif present in several eIF4E-binding proteins was found in this region. Furthermore, the wheat p86 subunit, a component of the plant translation eIF(iso)4F complex, was found to interfere with the AteIF(iso)4E-AtLOX2 interaction suggesting that p86 and AtLOX2 compete for the same site on eIF(iso)4E. These results may reflect a link between eIF4Es factors mediating translational control with LOX2 activity, which is probably conserved throughout the plant kingdom.

Amino Acid Sequence↗
PubMed1998

Relationship of the pelargonium flower break carmovirus (PFBV) coat protein gene with that of other carmoviruses.

The 3'-terminal 1500 nucleotides of the genome of pelargonium flower break carmovirus (PFBV) were sequenced from RT-PCR amplification products. One large ORF was found, encoding a 345 amino acid protein of Mr 37 kDa, which corresponds to the coat protein, as confirmed by immunoprecipitation of products of in vitro transcription and translation. The sequence also included the putative promoter of the coat protein gene subgenomic RNA, as well as its 5' and 3' untranslated regions. The PFBV coat protein was more similar to that of saguaro cactus virus and carnation mottle virus than to that of other carmoviruses. Despite the lower level of similarity of CP gene sequences compared to the RNA dependent RNA polymerase (RdRp) gene sequences of small icosahedral viruses used in taxonomic studies, PFBV CP sequence comparisons and alignments confirmed that PFBV is related to carmoviruses, tombusviruses and a dianthovirus, as previously concluded from the analysis of a PFBV RdRp gene fragment.

Base Sequence↗
PubMed1998

The Arabidopsis thaliana cDNAs coding for eIF4E and eIF(iso)4E are not functionally equivalent for yeast complementation and are differentially expressed during plant development.

Two cDNAs (At.EIF4E1 and At.EIF4E2) encoding, respectively, the eukaryotic initiation factors eIF4E and eIF(iso)4E of Arabidopsis thaliana were isolated by complementation of a Saccharomyces cerevisiae conditional mutant. The deduced amino acid sequences of the proteins are homologous to those from monocotyledonous plants, yeast and mammals. The corresponding genes were identified in YAC clones mapping to chromosome IV (At.EIF4E1) and to chromosome V (At.EIF4E2). The yeast strain complemented by At.EIF4E2 grew poorly compared with an isogenic strain expressing At.EIF4E1. Northern and in situ hybridization analysis show that both Arabidopsis At.EIF4E1 and At.EIF4E2 mRNAs are differentially accumulated in plant tissues. The At.EIF4E1 mRNA is expressed in all tissues except in the cells of the specialization zone of the roots; the At.EIF4E2 mRNA is particularly abundant in floral organs and in young developing tissues. This work further demonstrates an association between a high level of EIF4E mRNAs and cell proliferation and suggests that the plant eIF4E isoforms may have distinct functions in cell development and metabolism.

Amino Acid Sequence↗
PubMed1995

Functional characteristics of the maize RNA-binding protein MA16.

The maize RNA-binding protein MA16 is a non-ribosomal nucleolar protein widely distributed in different maize tissues. We have previously shown that the MA16 protein binds preferentially to guanosine- and uridine-rich sequences. As a step towards the identification of specific targets with which MA16 interacts within the cell, we investigated the RNA-binding affinities and several other aspects of the protein by using binding assays and immunochemistry. The MA16 protein showed a wide spectrum of RNA-binding activities with lower affinities to several RNAs that was salt and heparin-sensitive indicative of electrostatic interactions, and higher affinities to particular RNAs including rRNA and translatable mRNA sequences. Among the RNAs found associated with MA16 protein was that encoding MA16 itself. This observation raises the possibility that MA16 gene expression could be self-regulated. Immunoprecipitation studies showed that in vivo MA16 was phosphorylated and that MA16 interacts with RNAs through complex association with several proteins. These results suggest that both phosphorylation and interaction with other proteins may be involved in determining RNA-binding specificities of MA16 in the cell.

Heat-Shock Proteins↗
PubMed1992

RNA binding characteristics of a 16 kDa glycine-rich protein from maize.

We have previously described a developmentally regulated mRNA in maize that accumulates in mature embryos and is involved in a variety of stress responses in the plant. The sequence of the encoded 16 kDa protein (MA16) predicts that it is an RNA-binding protein, since it possesses a ribonucleoprotein consensus sequence-type RNA-binding domain (CS-RBD). To assess the predicted RNA binding property of the protein and as a starting point to characterize its function we have used ribohomopolymer-binding assays. Here we show that the MA16-encoded protein binds preferentially to uridine- and guanosine-rich RNAs. In light of these results a likely role for this protein in RNA metabolism during late embryogenesis and in the stress response is discussed.

Amino Acid Sequence↗
PubMed1990

Gene sequence, developmental expression, and protein phosphorylation of RAB-17 in maize.

The ABA-induced MA12 cDNA from maize, which encodes a set of highly phosphorylated embryo proteins, was used to isolate the corresponding genomic clone. This gene, called RAB-17 (responsive to ABA), encodes a basic, glycine-rich protein (mol. wt. 17,164) containing a cluster of 8 serine residues, seven of them contiguous. It is a homologue of the rice RAB-21 gene (Mundy J, Chua NH, EMBO J 7; 2279-2286, 1988). Phosphoamino acid analysis of the isolated protein indicates that only the serine residues are phosphorylated and a putative casein-type kinase phosphorylatable sequence was identified in the protein. The pattern of expression and in vivo phosphorylation of the RAB-17 protein was studied during maize embryo germination and in calli of both meristematic or embryonic origin. ABA treatment induced the synthesis of RAB-17 mRNA and protein in calli, however, the RAB-17 proteins were found to be highly phosphorylated only in embryos.

Abscisic Acid↗
PubMed1980

Distribution of peripherally stained neurons by the colloidal iron histochemical method in albino rat cerebral cortex. A quantitative study.

A few stained neurons were demonstrated in several cortical areas by the Colloidal Iron method. The intense positive histochemical reaction was located surrounding the perikaryon and some neuronal branches. A quantitative study demonstrated that the largest percentage of stained neurons was found in III, IV and V layers of the visual and auditory cortex. The number of stained neurons in the auditory cortex was greater than in the visual cortex. Statistically significant differences (Student's t-test) were obtained between layers I, II, III and VI of both cortical areas. In other cortical areas studied there were no stained neurons (area insularis ventralis, area entorhinalis and area piriformis).

Animals↗