Regressive events in brain development and scenarios for vertebrate brain evolution.

The problems of the evolution of varying brain size, the specialization of particular functional systems and overall differences in the relative complexity of brain organization are discussed in terms of alterations of regressive events in neurogenesis (cell death and axon retraction). Three scenarios for evolution, cascade reorganization, parcellation and heterochrony, are considered in light of regressive mechanisms during development.

Nucleotide sequence of the tra YALE region from IncFV plasmid pED208.

The pED208 plasmid is a 90-kilobase conjugative plasmid which is the derepressed form of Fo lac plasmid (IncFV). A 3.3-kilobase HindIII-PstI fragment from the pED208 plasmid was cloned and sequenced and was found to contain four open reading frames which were highly homologous to the traA, traL, traE, and traY gene products of the F plasmid.

Origin of transfer of IncF plasmids and nucleotide sequences of the type II oriT, traM, and traY alleles from ColB4-K98 and the type IV traY allele from R100-1.

The complete nucleotide sequences of the ColB4-K98 (ColB4) plasmid transfer genes oriT, traM, and traY as well as the traY gene of R100-1 are presented and compared with the corresponding regions from the conjugative plasmids F, R1, and R100. The sequence encoding the oriT nick sites and surrounding inverted repeats identified in F was conserved in ColB4. The adenine-thymine-rich sequence following these nick sites was conserved in R1 and ColB4 but differed in F and R100, indicating that this region may serve as the recognition site for the traY protein.

Nucleotide sequences of five IncF plasmid finP alleles.

The nucleotide sequences of five finP alleles from various IncF plasmids (finP types I to V) as well as of three finP mutations were determined and compared. The finP gene specificity could be attributed to a variable, six-to-seven-nucleotide loop located between inverted repeats, and the sequence data were consistent with the product of finP being an RNA molecule rather than a protein. The finP mutations interrupted a proposed finP promoter or destabilized a predicted stem-and-loop structure in the finP RNA molecule.

Location of the antigenic determinants of conjugative F-like pili.

The amino terminus of the pilin protein constitutes the major epitope of F-like conjugative pili studied to date (F, ColB2, R1-19, R100-1, and pED208). Anti-pED208 pilus antibodies were passed through a CNBr-Sepharose affinity column linked to bovine serum albumin which was conjugated to a synthetic peptide, AcP(1-12), containing the major epitope at the amino terminus of pED208 pilin. This allowed the separation of two classes of antibodies; one was specific for the amino terminus and bound to the column, while the other, which recognizes a second epitope on the pilus, did not bind to the column.

Control of cell number in the developing visual system. III. Effects of visual cortex ablation.

The effect of unilateral deletion of the visual cortex on early cell death and eventual cell number in various structures of the visual system was examined. At minimum, this manipulation potentially provides excess retinal afference to the superior colliculi, partially denervates the superior colliculi, reduces normal retinal terminal area and opens up potential target space for the retina and superior colliculus in those areas where they share terminal space with the visual cortex. All layers of the superior colliculus, bilaterally, showed an initial decrease in the rate of cell death relative to normal followed by an increase in cell death rates.

Control of cell number in the developing visual system. II. Effects of partial tectal ablation.

The effects of potential excess innervation on cell survival in the superior colliculus and related structures during the period of normally occurring cell death was examined. A unilateral, partial lesion of the superficial layers of the superior colliculus on the day of birth, which results in a compression of the retinotectal map into the remaining area, was the manipulation used to produce the potential excess innervation. Cell density was reduced in the tectal fragment early in development, consistent with hyperinnervation, but had returned to normal by the end of the period of normally occurring cell death.

Control of cell number in the developing visual system. I. Effects of monocular enucleation.

Monocular enucleation of hamsters on the day of birth caused an increase in cellular degeneration and a corresponding loss of cells in the dorsal lateral geniculate nucleus contralateral to the enucleation over the first 12 postnatal days. The superficial layers of the contralateral superior colliculus showed a similar increase in cell degeneration, except rostrally where the remaining ipsilateral projection is found. No changes in degeneration were found in either the ipsi- or contralateral ventral lateral geniculate nuclei, the intermediate and deep layers of the superior colliculus, or in the dorsal lateral geniculate and superficial superior colliculus ipsilateral to the enucleation, even though all were denervated to some degree.

Nucleotide sequence of the surface exclusion genes traS and traT from the IncF0 lac plasmid pED208.

pED208 is a 90-kilobase conjugative plasmid belonging to the incompatibility group IncF0 lac. The surface exclusion system from this plasmid was cloned and sequenced, and two genes demonstrated exclusion ability. traS encoded a 186-amino-acid hydrophobic protein which, when transcribed from a vector promoter, caused exclusion of pED208.

Novel serine proteases encoded by two cytotoxic T lymphocyte-specific genes.

Genes that are expressed exclusively in cytotoxic T cells should encode proteins that are essential for target cell lysis in cell-mediated immune responses. The sequences of two cytotoxic T lymphocyte-specific complementary DNA's (cDNA's) suggest that the two genes encode serine proteases. A full-length cDNA corresponding to one of the genes was isolated and sequenced.

Nucleotide sequences of the R1-19 plasmid transfer genes traM, finP, traJ, and traY and the traYZ promoter.

The complete nucleotide sequences of the R1 drd-19 (R1-19) plasmid transfer genes traM, finP, traJ, and traY and the region encoding the traYZ promoter were determined. The traM protein from R1-19 was similar to the 127-amino-acid traM product from the conjugative plasmid F; only 28 residues were not identical. finP, a negative regulatory element of the traJ gene, contained a 12-base-pair inverted repeat identical to that found in the F plasmid, but differed in the 7 base pairs found between the repeats.

Cell generation, death, and retinal growth in the development of the hamster retinal ganglion cell layer.

During the early postnatal period in the hamster, the retinal ganglion cell layer grows, establishes its central connections, and undergoes substantial cell loss. In this study, we describe the development of the retinal ganglion cell layer with particular attention to the creation of local specializations in cell density. Changes in the number and spatial distribution of cells identified by a single 3H thymidine injection were examined through the period of maximal cell loss (postnatal days 4-10) and at adulthood.

Expression of the Pseudomonas aeruginosa PAK pilin gene in Escherichia coli.

Pseudomonas aeruginosa is a piliated opportunistic pathogen. We have recently reported the cloning of the structural gene for the pilus protein, pilin, from P. aeruginosa PAK (B.

Characterization and sequence analysis of pilin from F-like plasmids.

Conjugative pili are expressed by derepressed plasmids and initiate cell-to-cell contact during bacterial conjugation. They are also the site of attachment for pilus-specific phages (f1, f2, and QB). In this study, the number of pili per cell and their ability to retract in the presence of cyanide was estimated for 13 derepressed plasmids.

Comparative studies of the amino acid and nucleotide sequences of pilin derived from Pseudomonas aeruginosa PAK and PAO.

The entire amino acid sequence for Pseudomonas aeruginosa PAO pilin was determined through peptide sequencing and from the complete nucleotide sequence encoding the pilin gene. The precursor PAO pilin is 149 amino acids in length which includes a 6-amino-acid positively charged leader sequence. Comparison of the amino acid sequences of pilin produced by P.

Temporal retina is preferentially represented in the early retinotectal projection in the hamster.

Retrograde transport of horseradish peroxidase (HRP) after complete transection of the brachium of the superior colliculus on the day of birth in hamsters revealed preferential labelling of the temporal retina. Cytochrome oxidase staining of the retina showed similar preferential temporal labelling. A discrete lack of label of the extreme temporal periphery of the retina contralateral to the HRP placement and a complementary label of ipsilateral temporal periphery were also observed.

Major antigenic determinants of F and ColB2 pili.

F-like conjugative pili are expressed by plasmids with closely related transfer systems. They are tubular filaments that are composed of repeating pilin subunits arranged in a helical array. Both F and ColB2 pilin have nearly identical protein sequences, and both contain an acetylated amino-terminal alanine residue.

Cloning and sequencing of the Pseudomonas aeruginosa PAK pilin gene.

A 1.2-kilobase (kb) HindIII restriction fragment containing the pilin gene from Pseudomonas aeruginosa PAK has been cloned and sequenced. The pilin protein is 144 amino acids in length with a positively charged leader sequence of 6 amino acids.

Regional differences in normally occurring cell death in the developing hamster lateral geniculate nuclei.

Normal cellular degeneration occurs in the lateral geniculate nuclei (LGN) of the hamster thalamus early in postnatal development. Degenerative debris can be observed in the ventral and dorsal nuclei at postnatal days 2-10 and is present in greater and more variable amounts in the ventral nucleus. Cell degeneration in the dorsal LGN is maximal at postnatal day 5, identical to the degeneration pattern of the hamster retina and superior colliculus, but shows a second peak at postnatal day 8 which may relate to the establishment of cortical connectivity.

Localization, cloning, and sequence determination of the conjugative plasmid ColB2 pilin gene.

ColB2 is a colicin-producing, 96-kilobase plasmid which encodes a conjugative system that is similar, but not identical, to F. A restriction map of this plasmid was generated, and DNA homology studies between F and ColB2 plasmids revealed homology only between their transfer operons. The locations of the ColB2 transfer operon and ColB2 pilin gene were localized on this restriction map.

Clinical trial of flupirtine maleate in patients with migraine.

A double-blind randomized parallel group trial was carried out in two centres to study the drug treatment of acute attacks of migraine. One group of 20 patients was treated with oral doses of 100 mg flupirtine maleate and another group of 20 patients with doses of 1 g paracetamol. In all cases, doses were taken as required up to a maximum of 4 doses per day for 5 days.

Characterization of conjugative plasmid EDP208.

EDP208 is a conjugative plasmid belonging to incompatibility group IncF0 lac, A restriction endonuclease map of this plasmid was constructed using five restriction enzymes: BamHI, HindIII, PvuI, SstI, and XhoI. On the basis of these mapping studies, the plasmid was found to be 90 kilobases in length. Clones were constructed from four large HindIII fragments of plasmid EDP208.

Respiration rates in heterotrophic, free-living protozoa.

Published estimates of protozoan respiratory rates are reviewed with the object of clarifying their value in ecological studies. The data show a surprisingly large variance when similarly sized cells or individual species are compared. This is attributed to the range of physiological states in the cells concerned.