Neurotensin and Neuromedin N Are Differently Metabolized in Ventral Tegmental Area and Nucleus Accumbens

Whole homogenates and membrane-bound and cytosoluble fractions prepared from rat ventral tegmental area (VTA) and nucleus accumbens were examined for their content of peptidasic activities and for their ability to metabolize neurotensin and its natural related hexapeptide neuromedin N. No qualitative differences were observed between these two brain regions concerning the presence and the subcellular distribution of a series of activities able to hydrolyze various specific fluorimetric enzymatic substrates. However, aminopeptidase B, endopeptidase 24-15, and endopeptidase 24-11 were significantly lower in the VTA than in the nucleus accumbens membrane preparations, while proline endopeptidase was detected in significantly higher amount only in the cytosolic fraction prepared from nucleus accumbens. Both neurotensin and neuromedin N were metabolized more rapidly in the nucleus accumbens than in the VTA. Furthermore, the degradation rate of neuromedin N was considerably faster than that of neurotensin whatever the cerebral area examined. Studies carried out with highly specific peptidase inhibitors revealed that endopeptidase 24-15 mainly contributed to the catabolism of neurotensin in homogenates and membrane-bound preparations of nucleus accumbens and VTA, while aminopeptidase B appeared predominantly responsible for the rapid disappearance of neuromedin N in both cerebral tissues. The possibility that the different metabolic processes of the two peptide congeners could explain their distinct pharmacological profiles observed after their microinjection in the nucleus accumbens and in the VTA is discussed.     

Synthesis of Tricyclic Phenylpyrrole Lactams, New Models of Antitubulin Agents

The tricyclic lactams 3 and 4 having a phenylpyrrole framework have been prepared from the arylpyrroles 5 and 16 respectively. These structural analogs of rhazinilam 1 present, like the latter, an interesting antitubulin and cytotoxic activity.     

Isolation of a cDNA fragment coding for Chlamydomonas reinhardtii ferredoxin and expression of the recombinant protein in Escherichia coli

A cDNA clone coding for mature C. reinhardtii ferredoxin has been isolated from a cDNA library using PCR and two oligonucleotide primers based on the N- and C-termini of the protein's amino acid sequence. The nucleotidic sequence of the PCR fragment (299 bp) agreed well with the amino acid sequence since a single conservative substitution (Thr-7 to Ser) could be deduced. The PCR fragment was inserted into the expression vector pTrc 99A, using the incorporated NcoI and BamHI restriction sites and the construction used to transform E. coli (DH5α F′). After subsequent large scale expression and purification of the recombinant protein, biochemical and biophysical analysis have indicated that the product isolated from E. coli is homologous to native ferredoxin isolated from green algae.     

Group composition in wild and commensal hamadryas baboons: A comparative study in Saudi Arabia

Papio hamadryas was surveyed throughout its range in Saudi Arabia and was observed at altitudes ranging from 0 to 2300 m. Wild populations occur along the whole range of altitude, while commensal populations are only found above 850 m altitude. No variation in group size was found with altitude. Comparison of wild and commensal populations showed the following. (1) Their composition in terms of age and sex classes, overall adult sex ratios, and group size does not significantly differ. (2) Groups of both populations include, in similar proportions, three types of parties: one-male units (>70%), two-male units (>13%), and a few other units of variable composition. (3) The mean size of commensal parties is significantly larger than in the wild population; specifically one-male units are larger in the commensal population due to a larger number of females per male. Thus, female distribution in commensal groups is more inequitable than that in wild groups. (4) Finally, the number of females included in two-male units increases with altitude. These differences are discussed in terms of food availability and predator pressure and are compared with results obtained on other Arabian and Ethiopian populations.     

The distribution ofPapio hamadryas in Saudi Arabia: Ecological correlates and human influence

We describe the distribution ofPapio hamadryas in Saudi Arabia in relation to ecological constraints and recent changes in human activities and land use. Baboons are present only in the Sarawat and southern Hijaz mountains, which border the Red Sea in the southwestern region of the country. Our distribution data confirms that their range, described as of 1981, should be extended 200 km northward, from 21°40N (Taif) to 23°20N (Al Akhal). This new limit of range is not due to recent deployment of the baboons, but instead corrects inaccurate surveys by previous reporters. Ecological factors that affect baboon distribution include low annual rainfall (less than 100 mm per yr), which limits baboon range in the north and east, and the absence of suitable sleeping cliffs in the coastal plain, which limits their range in the west. Relative abundance is discussed in relation to vegetation and predator distribution. Human influence is also significant: commensal troops persist near urban centers, while agricultural development reduces baboon numbers in some regions. Habitat characteristics are discussed in comparison with similar data on the range of hamadryas in Ethiopia.     

In vitro evaluation of sugarcane resistance to gumming disease and of Xanthomonas campestris pv. vasculorum aggressiveness

Sugarcane plantlets were sectioned halfway between the base and the youngest ligule and then inoculated by soaking the wound in a suspension of Xanthomonas campestris pv. vasculorum. The infection caused rapid necrosis of the inoculated leaves, chlorosis of uninoculated leaves, or death of the inoculated plantlet. New tillers sometimes showed chlorosis or white streaks. The effects of the inoculum concentration, the cultivar, and the bacterial strain on symptom severity were determined. The ranking of cultivars depended on the inoculum concentration, and strains were found to differ with regard to aggressiveness. However, cultivars and strains were more effectively classified in greenhouse trials. The poor expression of leaf resistance appeared to limit the use of the in vitro test.     

Disruption of imprinting by memory inhibitors

Several amnestic drugs were administered intracranially to day-old chicks at selected times around a 10-min exposure to an imprinting stimulus. The drugs used were monosodium glutamate, ouabain, cycloheximide and amino-iso-butyrate. The chicks were tested for 10 min in the same apparatus two days later, and the time spent following the stimulu was recorded., The index of memory retention was the difference between the time spent following on test and the time spent following on the initial exposure. When compared with saline-injected control, glutamate administered 5 min before the beginning of the initial exposure was effective in producing a reduction in following times and hence amnesia. Ouabian was effective when injeced before the beginning and immediately after the end of the initial exposure; while cycloheximide was effective when administered as late as 5 min after the initial exposure. The effective times of administration for the drugs to produce a reduction in following times were similar to that observed for amnesia in passive avoidance memory tasks. The increase in following shown by the control chicks was not a developmental effect due to the increae in age on test. Experiments involving a choice of stimuli on test support the invovement of a memoryrelated phenomenon in these experiments.