SPERMATOGENESIS IN COLEOCHAETE PULVINATA (CHAROPHYCEAE): EARLY BLEPHAROPLAST DEVELOPMENT

Transmission electron microscopy of serial thin sections was used to reconstruct several early developmental stages of the blepharoplast in Coleochaete pulvinata spermatids. These were compared to published studies of blepharoplast development in Charales and the closest relatives of charophycean green algae among embryophytes, i.e., hornworts and liverworts. Bicentriolar centrosomes such as occur in bryophytes and fern allies were not observed in Coleochaete. Centriole replication in C. pulvinata was orthogonal as in Charales. The resulting two daughter centrioles were oriented perpendicularly and joined proximally by electron-dense material. Their orthogonal relationship was maintained throughout blepharoplast development by a massive, banded connective which appeared early. In spermatids of hornworts and liverworts, a multilayered structure (MLS) develops in association with two centrioles destined to become flagellar basal bodies. When the MLS of these lower land plants is sectioned at right angles to the long axis of the microtubular layer, the MLS is observed to lie beneath cross sections of both centrioles. In contrast, when developing MLSs of C. pulvinata and Charales are similarly sectioned, they occur beside a cross section of just one of the two centrioles. In C. pulvinata (as in other charophytes), MLS lamellae are oriented at a 90-degree angle to the long axis of the S₁ microtubules from the beginning. This contrasts with the 40–45 degree angle between the MLS lamellae and S₁ microtubules universally reported for archegoniates. In early C. pulvinata spermatids, spline microtubules are closely associated with an anterior mitochondrion having a low stromal density and few cristae. An anterior mitochondrion is typically associated with blepharoplast development in hornworts and liverworts, but has not previously been reported to occur in Coleochaete or any other charophycean alga. In Coleochaete, as in hornworts and liverworts, but unlike Charales, structure of mature blepharoplasts reflects early blepharoplast ontogeny. Very little change in positional relationships among blepharoplast components (flagella, connective, MLS) occurs during development. These character-state differences are of importance in cladistic analyses of charophycean algae and lower land plants.     

Prospective evaluation of eligibility for thrombolytic therapy in acute myocardial infarction.

OBJECTIVES--To determine the proportion of patients presenting with acute myocardial infarction who are eligible for thrombolytic therapy. DESIGN--Cohort follow up study. SETTING--The four coronary care units in Auckland, New Zealand. SUBJECTS--All 3014 patients presenting to the units with suspected myocardial infarction in 1993. MAIN OUTCOME MEASURES--Eligibility for reperfusion with thrombolytic therapy (presentation within 12 hours of the onset of ischaemic chest pain with ST elevation > or = 2 mm in leads V1-V3, ST elevation > or = 1 mm in any other two contiguous leads, or new left bundle branch block); proportions of (a) patients eligible for reperfusion and (b) patients with contraindications to thrombolysis; death (including causes); definite myocardial infarction. RESULTS--948 patients had definite myocardial infarction, 124 probable myocardial infarction, and nine ST elevation but no infarction; 1274 patients had unstable angina and 659 chest pain of other causes. Of patients with definite or probable myocardial infarction, 576 (53.3%) were eligible for reperfusion, 39 had definite contraindications to thrombolysis (risk of bleeding). Hence 49.7% of patients (537/1081) were eligible for thrombolysis and 43.5% (470) received this treatment. Hospital mortality among patients eligible for reperfusion was 11.7% (55/470 cases) among those who received thrombolysis and 17.0% (18/106) among those who did not. CONCLUSIONS--On current criteria about half of patients admitted to coronary care units with definite or probable myocardial infarction are eligible for thrombolytic therapy. Few eligible patients have definite contraindications to thrombolytic therapy. Mortality for all community admissions for myocardial infarction remains high.     

Flight initiation byProstephanus truncatus in relation to time of day, temperature, relative humidity and starvation

Studies were carried out in the laboratory on the influences of time of day, temperature, relative humidity and starvation on flight initiation byProstephanus truncatus (Horn) (Coleoptera: Bostrichidae). Flight occurred throughout the 12 h photophase and at the beginning of the scotophase but peaked at 2–0 h before darkness. Temperature exerted a significant effect on flight. The frequency of flight take-off increased with temperature over the range 20–30°C but declined sharply at 35°C. Flight activity increased with starvation up to a maximum at 2 days after which it began to decline.     

A microtiter solid phase radioimmunoassay for detection of the human reovirus-like agent in stools.

The development of a microtiter solid-phase radioimmunoassay for detection of the human reovirus-like (RVL) agent is described. The test is simple to perform and uses small amounts of reagents; a large number of specimens can rapidly be tested in a single test. Both filtered and unfiltered stool suspensions can be employed. The test was as sensitive as immune electron microscopy, and with an appropriate blocking test, was specific for the human RVL agent.     

Cyclic nucleotide phosphodiesterases in the cricket, Acheta domesticus.

Exceptionally high levels of guanosine 3'-5'-cyclic monophosphate (cyclic GMP) in the accessory reproductive gland of the male house cricket, Acheta domesticus, led to an investigation of cyclic nucleotide phosphodiesterase (EC 3.1.4.--) as a possible regulatory enzyme. Cricket cyclic nucleotide phosphodiesterase activity with cyclic GMP or cyclic AMP as substrate had a pH optimum around 9.0, required Mg2+ or Mn2+ for maximal activity, and was inhibited by EDTA and methylxanthines. Cyclic GMP phosphodiesterase occurred mainly in the soluble fraction of homogenates of accessory glands or whole crickets, but cyclic AMP phosphodiesterase in the accessory gland was primarily particulate. Kinetic analysis indicated three forms of cyclic GMP phosphodiesterase, with Km values at 2.9 muM, 71 muM and 1.5 mM. Chromatography of whole cricket or accessory gland extracts on DEAE cellulose gave an initial peak having comparable activity with either cyclic GMP or cyclic AMP, and a second peak specific for cyclic AMP. There were no appreciable changes in the specific activity or kinetic properties of accessory gland cyclic GMP phosphodiesterase during a developmental period over which cyclic GMP levels rise more than 500-fold. Thus, the accumulation of cyclic GMP in the accessory gland is probably not associated with concomitant developmental modulation of phosphodiesterase activity.     

Reduction of REM sleep by a tryptophan-free amino acid diet.

The acute administration of a tryptophan-free amino acid diet to rats has previously been reported to produce a marked reduction in brain serotonin concentrations. The present study examined the effects of such a diet on electroencephalographic sleep measures. There was a decrease in REM sleep and a small increase in nonREM sleep, with no change in total sleep time. In view of these and other observations, the hypothesis that the serotonergic system plays an important role in the maintenance of nonREM sleep should be carefully reevaluated.     

Vimentin is transiently co-localized with and phosphorylated by cyclic GMP-dependent protein kinase in formyl-peptide-stimulated neutrophils.

The effects of cGMP-dependent protein kinase (G-kinase), a major cellular receptor of cGMP, were investigated in activated human neutrophils. Immunocytochemistry demonstrated that G-kinase translocated from a diffuse localization in the cytoplasm to the cytoskeleton and nucleus after stimulation with N-formyl-methionyl-leucyl-phenylalanine (fMLP), and transiently co-localized with the intermediate filament protein, vimentin. During this time period, the most remarkable co-localization of G-kinase and vimentin was observed between 1-2.5 min stimulation with fMLP. At that time co-localization of G-kinase and vimentin was predominantly confined to filaments which extended from regions adjacent to the nucleus into the uropod. Distinctive localization for only G-kinase was observed at the microtubule organizing center and euchromatin of the nucleus. The filamentous staining pattern for G-kinase and vimentin was enhanced in the presence of 8-Br-cGMP. Coincident with co-localization of G-kinase and vimentin in adherent neutrophils was a transient increase in cGMP levels and an increase in the phosphorylation of vimentin in fMLP-stimulated cells. The increase in cGMP levels was dependent upon cell adherence, was enhanced by preincubating neutrophils with L-arginine (the precursor for nitric oxide synthesis), and attenuated with the nitric oxide synthase inhibitor, NG-monomethyl-L-arginine. Phosphorylation of vimentin in the fMLP-stimulated neutrophil was observed in the presence or absence of exogenous cGMP, although in the presence of low concentrations of 8-Br-cGMP a more rapid phosphorylation of vimentin was observed that correlated with the enhanced co-localization of G-kinase and vimentin. Phosphorylation of vimentin was not observed in non-activated cells treated with 8-Br-cGMP, suggesting that phosphorylation only occurs when G-kinase is co-localized with vimentin. The presence of the protein kinase C inhibitors, staurosporine or H-7, did not inhibit vimentin phosphorylation during fMLP stimulation, while 8-Br-cGMP enhanced phosphorylation in fMLP-treated cells. This suggests that neither protein kinase C nor cAMP-dependent protein kinase catalyze the phosphorylation of vimentin in neutrophils activated by fMLP. These results indicate that vimentin and G-kinase are co-localized in neutrophils and that vimentin is phosphorylated by G-kinase in response to the co-localization of the two proteins. A model for the targeting of G-kinase and vimentin is presented which hypothesizes that the transient redistribution of G-kinase may regulate neutrophil activation.     

Human herpesvirus 7 is a constitutive inhabitant of adult human saliva.

We report the frequent isolation of human herpesvirus 7 from the saliva of healthy adults. Virus isolates recovered from different individuals exhibited minimal restriction enzyme polymorphism, which was mostly confined to heterogeneous (het) sequences in the genome. DNAs of isolates recovered from the same individual over a period of several months showed the same characteristic het fragments, indicating the stability of the het sequences upon virus replication and shedding in vivo. In contrast to the results of previous reports, human herpesvirus 6, the causative agent of roseola infantum, could not be isolated from the saliva specimens, raising questions regarding oral transmission of human herpesvirus 6 and human herpesvirus 7 to young children.