Effects of oxytocin and methacholine on cyclic nucleotide levels of rabbit myometrium

The effects of oxytocin and methacholine on cyclic nucleotide levels in estrogen-primed rabbit myometrium were studied in the presence and absence of 1-methyl-3-isobutyl xanthine (MIX), a phosphodiesterase inhibitor. In the absence of MIX, methacholine increased guanosine 3',5'-cyclic monophosphate (cGMP) levels at a time when contraction was decreasing, but had no influence on adenosine 3',5'-cyclic monophosphate (cAMP) levels. In contrast, oxytocin did not elevate cGMP, but rapidly decreased cAMP levels. MIX (1 mM) increased both cAMP and cGMP levels. Oxytocin or methacholine further increased cGMP, indicating activation of guanylate cyclase. Oxytocin- but not methacholine-induced stimulation of guanylate cyclase was abolished in Ca2+-free solution. Oxytocin increased cAMP over the levels produced by MIX alone, whereas methacholine decreased cAMP below the MIX control values; these effects were insensitive to indomethacin. Tissue levels of cGMP and cAMP did not directly correlate with isometric tension. The results also indicate that both oxytocin and methacholine stimulate guanylate cyclase but have opposing effects on adenylate cyclase of rabbit myometrium.     

A polychromator-based microspectrophotometer

A microspectrophotometer is a digital microscope used to measure absorption and fluorescence spectra. In this paper we describe a polychromator-based microspectrophotometer that performs in vivo absorption or emission measurements at the same time on different subcellular compartments such as photoreceptive and photosynthetic structures of algal cells. In this system, a flat field imaging concave grating polychromator is connected to the slit-shaped exit pupil of a light-guide probe mounted onto a microscope equipped with an epifluorescence module. The subcellular components, on which the spectra will be measured, are placed in the microscope field and finely adjusted. The outer bundle of the probe is used for centering the objects, while the central bundle of the probe, containing 19 light guides, is used for acquiring either transmitted or emitted light (i.e. fluorescence). The light transmitted or emitted by the subcellular components is collected by the probe mounted in the back focal plane of the ocular. The exit pupil of this probe, connected to a flat field imaging concave grating polychromator, produces a dispersion image that in turn is focused onto a digital slow scan cooled CCD camera. Absorption and emission spectra of algal subcellular compartments are presented.     

Cytogenetic findings in 4952 prenatal diagnoses. An Italian collaborative study

Summary The development of prenatal diagnosis in Italy was made difficult by the restrictions of the old abortion law and only in recent years has a consistent number of cases been investigated. We report the experience on prenatal chromosome diagnosis of ten Italian centers participating in a collaborative study on 4952 diagnoses performed from 1972 to 1980. The main indication groups were: advanced maternal age (2882 cases), previous child with chromosome anomaly from parents with normal karyotype (847 cases), and chromosome anomaly in one parent (97 cases). The other indications for amniocentesis, including cases without a cytogenetic risk, have been assembled into a miscellaneous group (1126 cases). We found 125 abnormal fetal karyotypes (2.5%) of which 89 were unbalanced (1.8%). The frequencies and types of chromosome anomalies are reported in detail for each indication group and are compared with the corresponding ones from the European Munich Conference. The great majority of these Italian data were not included in the Munich report.     

A segment of the apospory-specific genomic region is highly microsyntenic not only between the apomicts Pennisetum squamulatum and buffelgrass, but also with a rice chromosome 11 centromeric-proximal genomic region

Bacterial artificial chromosome (BAC) clones from apomicts Pennisetum squamulatum and buffelgrass (Cenchrus ciliaris), isolated with the apospory-specific genomic region (ASGR) marker ugt197, were assembled into contigs that were extended by chromosome walking. Gene-like sequences from contigs were identified by shotgun sequencing and BLAST searches, and used to isolate orthologous rice contigs. Additional gene-like sequences in the apomicts' contigs were identified by bioinformatics using fully sequenced BACs from orthologous rice contigs as templates, as well as by interspecies, whole-contig cross-hybridizations. Hierarchical contig orthology was rapidly assessed by constructing detailed long-range contig molecular maps showing the distribution of gene-like sequences and markers, and searching for microsyntenic patterns of sequence identity and spatial distribution within and across species contigs. We found microsynteny between P. squamulatum and buffelgrass contigs. Importantly, this approach also enabled us to isolate from within the rice (Oryza sativa) genome contig Rice A, which shows the highest microsynteny and is most orthologous to the ugt197-containing C1C buffelgrass contig. Contig Rice A belongs to the rice genome database contig 77 (according to the current September 12, 2003, rice fingerprint contig build) that maps proximal to the chromosome 11 centromere, a feature that interestingly correlates with the mapping of ASGR-linked BACs proximal to the centromere or centromere-like sequences. Thus, relatedness between these two orthologous contigs is supported both by their molecular microstructure and by their centromeric-proximal location. Our discoveries promote the use of a microsynteny-based positional-cloning approach using the rice genome as a template to aid in constructing the ASGR toward the isolation of genes underlying apospory.     

Synthesis of oxytocin using iodine for oxidative cyclization and silica gel adsorption chromatography for purification.

Oxytocin (OT) was synthesized employing the solid phase method. Resins made of copolymers of polystyrene-1%-crosslinked with divinylbenzene gave better yields (73-95%) of Z-Cys(Bzl)-Tyr(Bzl)-Ile-Gln-Asn-Cys(Bzl)-Pro-Leu-Gly-NH2 (I) than 2%-crosslinked resins (10--56%). Reduction of I with Na-liq.NH3 and oxidation with I2-MeOH at -40 degrees minimized dimer and polymer formation, and resulted in good yields (49--54%) of OT. The large volumes of MeOH required when several grams of I are reduced and then oxidized were rapidly evaporated in vacuo, and the residue was desalted by dissolving the peptide in a small volume of glacial acetic acid and filtering to remove the salt. OT was purified by adsorption chromatography on a silica gel column with combinations of MeOH-CHCl3 of graded polarity. Oxytocin elutes with 33% MeOH-CHCl3. After two purification steps by adsorption chromatography, the resulting OT was found to be homogeneous. The hormone was characterized chemically and found to be active biologically.     

Cytochemical Ca2+ Distribution in Activated Discoglossus pictus Eggs: A Gradient in the Predetermined Site of Fertilization

The K-pyroantimonate/OsO₄ (PA) cytochemical method coupled with EGTA and X-ray microanalytical controls has been used to localize Ca²⁺ at egg activation in Discoglossus pictus eggs. The results show that: 1) the PA method is able to selectively localize Ca²⁺ pools mobilized by activating stimuli; 2) the smooth endoplasmic reticulum (SER) elements located in the animal dimple region, i.e. in the predetermined site of fertilization, are the first egg components labeled by precipitates; 3) a decreasing gradient of precipitates is present from the center beyond the boundaries of the dimple region; 4) precipitates are lacking in the remainder of the egg even at late times after activation.
The possibilities are discussed that a) SER is the major Ca²⁺-releasing store at activation in Discoglossus , and b) the observed gradient of pyroantimonate-detected Ca²⁺ reflects an ionic Ca²⁺ gradient.     

Long-term occupational exposure to organic solvents affects color vision, contrast sensitivity and visual fields

The purpose of this study was to evaluate the visual outcome of chronic occupational exposure to a mixture of organic solvents by measuring color discrimination, achromatic contrast sensitivity and visual fields in a group of gas station workers. We tested 25 workers (20 males) and 25 controls with no history of chronic exposure to solvents (10 males). All participants had normal ophthalmologic exams. Subjects had worked in gas stations on an average of 9.6±6.2 years. Color vision was evaluated with the Lanthony D15d and Cambridge Colour Test (CCT). Visual field assessment consisted of white-on-white 24–2 automatic perimetry (Humphrey II-750i). Contrast sensitivity was measured for sinusoidal gratings of 0.2, 0.5, 1.0, 2.0, 5.0, 10.0 and 20.0 cycles per degree (cpd). Results from both groups were compared using the Mann–Whitney U test. The number of errors in the D15d was higher for workers relative to controls (p<0.01). Their CCT color discrimination thresholds were elevated compared to the control group along the protan, deutan and tritan confusion axes (p<0.01), and their ellipse area and ellipticity were higher (p<0.01). Genetic analysis of subjects with very elevated color discrimination thresholds excluded congenital causes for the visual losses. Automated perimetry thresholds showed elevation in the 9°, 15° and 21° of eccentricity (p<0.01) and in MD and PSD indexes (p<0.01). Contrast sensitivity losses were found for all spatial frequencies measured (p<0.01) except for 0.5 cpd. Significant correlation was found between previous working years and deutan axis thresholds (rho = 0.59; p<0.05), indexes of the Lanthony D15d (rho = 0.52; p<0.05), perimetry results in the fovea (rho = −0.51; p<0.05) and at 3, 9 and 15 degrees of eccentricity (rho = −0.46; p<0.05). Extensive and diffuse visual changes were found, suggesting that specific occupational limits should be created.     

Phenology and field biology of black cutworm (Lepidoptera: Noctuidae) in Ontario no-till corn

Black cutworm, Agrotis ipsilon (Hufnagel), is an occasional corn, Zea mays L., pest that is attracted to no-till fields. Understanding the phenology of black cutworm in Ontario no-till corn, particularly the time of arrival of adults in relation to the onset of crop damage and the stages of larvae that coincide with vulnerable corn seedling leaf stages, is important for their effective control. Pheromone and blacklight trap captures of moths first occurred in early April, whereas significant influxes did not occur until mid- to late April. Males and females were often captured simultaneously, in contrast to findings in Iowa and Illinois where males were captured in pheromone traps on average 3 wk ahead of females or males in blacklight traps. This may be a reflection of a more mature source population for the influxes into Ontario because first captures also were later than in the United States. Females arrived mated and corn seedling cutting occurred within 137 degree-days (DD) (base 10.4 degrees C) of first capture in Ontario corn. Cutworms were present in cornfields before planting, and the mean age of larvae increased along with corn leaf stage, suggesting that no new recruitment took place after planting. The apparent synchrony between corn and cutworm phenology in the northern areas of corn production seems more related to the availability and quality of food for young larvae relative to the development of the crop then the time of arrival of moths.     

Isolation of the photoreceptor (paraflagellar body) of the phototactic flagellate Euglena gracilis

We have described a procedure for isolating photoreceptors (paraflagellar bodies) from the unicellular phototactic alga Euglena gracilis. This procedure elicited the evagination of the reservoir membrane, and the detachment of the flagellar apparatus due to the very high concentration of CaCl₂ in the isolation solution that caused a frenetical acceleration of the flagellar beating.