Insect pollination for most of angiosperm evolutionary history

Most contemporary angiosperms (flowering plants) are insect pollinated, but pollination by wind, water or vertebrates occurs in many lineages. Though evidence suggests insect pollination may be ancestral in angiosperms, this is yet to be assessed across the full phylogeny. Here, we reconstruct the ancestral pollination mode of angiosperms and quantify the timing and environmental associations of pollination shifts. We use a robust, dated phylogeny and species-level sampling across all angiosperm families to model the evolution of pollination modes. Data on the pollination system or syndrome of 1160 species were collated from the primary literature. Angiosperms were ancestrally insect pollinated, and insects have pollinated angiosperms for c. 86% of angiosperm evolutionary history. Wind pollination evolved at least 42 times, with few reversals to animal pollination. Transitions between insect and vertebrate pollination were more frequent: vertebrate pollination evolved at least 39 times from an insect-pollinated ancestor with at least 26 reversals. The probability of wind pollination increases with habitat openness (measured by Leaf Area Index) and distance from the equator. Our reconstruction gives a clear overview of pollination macroevolution across angiosperms, highlighting the long history of interactions between insect pollinators and angiosperms still vital to biodiversity today.

Disaster declarations associated with bushfires, floods and storms in New South Wales, Australia between 2004 and 2014

Australia regularly experiences disasters triggered by natural hazards and New South Wales (NSW) the most populous State is no exception. To date, no publically available spatial and temporal analyses of disaster declarations triggered by hazards (specifically, bushfires, floods and storms) in NSW have been undertaken and no studies have explored the relationship between disaster occurrence and socio-economic disadvantage. We source, collate and analyse data about bushfire, flood and storm disaster declarations between 2004 and 2014. Floods resulted in the most frequent type of disaster declaration. The greatest number of disaster declarations occurred in 2012–2013. Whilst no significant Spearman’s correlation exists between bushfire, flood and storm disaster declarations and the strength of the El Niño/Southern Oscillation (ENSO) phase, we observe that bushfire disaster declarations were much more common during El Niño, and flood disaster declarations were five times more common during La Niña phases. We identify a spatial cluster or ‘hot spot’ of disaster declarations in the northeast of the State that is also spatially coincident with 43% of the most socio-economically disadvantaged Local Government Areas in NSW. The results have implications for disaster risk management in the State.

ANALYSIS OF MUSCLE CONTRACTION BY ULTRAVIOLET MICROBEAM DISRUPTION OF SARCOMERE STRUCTURE

In an effort to differentiate between the sliding filament theory for muscle contraction and alternative views which propose attachment between actin and myosin filaments at or across the H zone, rabbit psoas myofibrils were irradiated in various areas of the sarcomere with an ultraviolet microbeam. Irradiation of the I band appears to destroy the actin filaments; in vitro irradiation of F actin causes an irreversible depolymerization of the protein. Irradiation of the A band disorients the myosin but causes no apparent loss of dry mass. These effects are maximal at the wavelength of maximum absorption of the proteins involved. Actin filaments, released at the Z line of a sarcomere, are seen to slide into the A band on addition of ATP. Irradiation of a full A band prevents contraction, whereas irradiation of two-thirds of the A band, leaving a lateral edge intact, permits contraction at the non-irradiated edge. Thus contraction can occur in what is in essence only one-third of a sarcomere, eliminating any necessity for postulated H zone connections. These observations are in complete accord with the classical sliding filament theory but incompatible with either the contralateral filament hypothesis or the actin folding model for muscle contraction.

Multiple protein differences distinguish clam leukemia cells from normal hemocytes: evidence for the involvement of p53 homologues

In coastal locations, marine invertebrates, primarily molluscs, develop fatal leukemias in their blood or hemolymph. In the clam Mya arenaria, non-adhesive, mitotic, spherical leukemia cells replace adhesive, motile, normal hemocytes as leukemia progresses. End-stage leukemia cells express a unique antigen, IE10, while normal cells express the 2A4 marker. The goals of this work were to further differentiate the normal and leukemia specific antigens relative to protein structure, determine if other protein distinctions exist, and examine p53 gene family expression in both cell types. Recognized by the monoclonal antibody 2A4, normal cells express a 185-kDa glycoprotein that may have multiple forms. Detected by the monoclonal antibody 1E10, leukemic cells express a very hydrophobic 252-kDa glycoprotein that is likely to be a transmembrane protein with spectrin/dystrophin-like characteristics. After normalization to the major cytoskeletal protein actin, sodium dodecyl sulfate-polyacrylamide gel electrophoresis reveals major distinguishing protein and glycoprotein differences between the two cell types. Most obvious is the near-absence of tubulin in the non-mitotic normal hemocytes. We have also characterized the expression of p53 gene family members in normal and end-stage leukemia cells, finding shifts in expression of the p53 gene homologues p73 and p97 coincident with leukemia-specific protein synthesis.

Ciliary protein turnover continues in the presence of inhibitors of golgi function: evidence for membrane protein pools and unconventional intracellular membrane dynamics

The intimate association of the Golgi apparatus with cilia suggests a functional alliance. To explore the relationship between the synthesis and processing of membrane constituents and the turnover or regeneration of cilia, parallel cultures of gastrula-stage sea urchin embryos were pulse-chase labeled with (3)H-leucine in the presence of monensin, brefeldin A, or colchicine. Steady-state labeled cilia were isolated, and the embryos were allowed to regenerate cilia, which were then isolated after the equivalent of two normal regeneration times. Regeneration was absent in colchicine, minimal in monensin, and inhibited about 40% by brefeldin A. Both monensin and brefeldin A effectively inhibited the post-translational processing of prominent phosphatidylinositoylated and palmitoylated membrane proteins and the axoneme-associated transmembrane Spec3 protein, yet most other membrane plus matrix and 9+2 axonemal proteins were labeled to levels indistinguishable from untreated controls. However, total protein analysis of the membrane plus matrix fractions showed a substantial increase in glycoproteins and the calsequestrin-like protein ECaSt/PDI after treatment at steady-state with all three inhibitors and after regeneration in brefeldin A. Other constituents of this compartment, such as membrane-associated tubulin, calmodulin, and a 53-kDa calcium-binding protein, were unchanged. Therefore, inhibition of Golgi function via three different mechanisms left 9+2 protein turnover undiminished but resulted in an accumulation, in the cilium, of already-processed membrane pool constituents and a normally ER-resident protein. A disproportionate elevation of HSP70 suggests that a novel stress response may be involved in inhibiting ciliary regeneration or promoting glycoprotein augmentation.

Expression of homologues for p53 and p73 in the softshell clam (Mya arenaria), a naturally-occurring model for human cancer

Homologues for human p53 (Hsp53) and p73 (Hsp73) genes were cloned and expression patterns for their corresponding proteins analysed in tissues from normal and leukemic softshell clams (Mya arenaria). These are the first structural and functional data for p53 and p73 cDNAs and gene products in a naturally occurring, non-mammalian disease model. Core sequence of the predicted clam p53 (Map53) and p73 (Map73) proteins is virtually identical and includes the following highly conserved regions: the transcriptional activation domain (TAD), MDM2 binding site, ATM phosphorylation site, proline rich domain, DNA binding domains (DBDs) II-V, nuclear import and export signals and the tetramerization domain. The core sequence is a structural mosaic of the corresponding human proteins, with the TAD and DBDs resembling Hsp53 and Hsp73, respectively. This suggests that Map53 and Map73 proteins may function similarly to human proteins. Clam proteins have either a short (Map53) or long (Map73) C-terminal extension. These features suggest that Map53 and Map73 may be alternate splice variants of a p63/p73-like ancestral gene. Map73 is significantly upregulated in hemocytes and adductor muscle from leukemic clams. In leukemic hemocytes, both proteins are absent from the nucleus and sequestered in the cytoplasm. This observation suggests that a non-mutational p53/p73-dependent mechanism may be involved in the clam disease. Further studies of these gene products in clams may reveal p53/p73-related molecular mechanisms that are held in common with Burkitt's lymphoma or other human cancers.

Polychlorinated biphenyls are selectively neurotoxic in the developing Spisula solidissima embryo

Polychlorinated biphenyls (PCBs) are ubiquitous environmental pollutants that accumulate to toxic levels in the food chain. Using Spisula solidissima (surf clam) embryos as a developmental model, it was shown that Aroclor 1254 specifically targets two neuronal structures during embryonic development. Embryos were exposed to 1, 10), or 100 ppm Aroclor 1254 or an acetone vehicle control posthatching for 24, 48, and 72 h. Embryos labeled with a serotonin antibody or a neural antigen antibody and a rhodamine-conjugated secondary antibody were viewed by confocal microscopy. The cerebropleural ganglion showed a decrease both in serotonin production and in the size of the serotonin-synthesizing region upon exposure to 10 and 100 ppm Aroclor 1254. These decreases were detectable as early as 48 h postfertilization. When exposed to 100 ppm Aroclor 1254, the primitive neural plexus, which coordinates the movements of the mouth and velum, showed a delay in onset and cessation of expression of a molluscan-specific neural antigen. Exposure to Aroclor 1254 did not affect the overall growth and morphology of the embryos. In addition, analyses of total protein profiles and heat-shock protein 70 levels showed that exposure to Aroclor 1254 did not trigger protein degradation or cause a stress or shock response. These results show that exposure of Spisula embryos to Aroclor 1254 specifically targets neurogenesis while having no effect on the overall growth of the embryo.

Preferential incorporation of tubulin into the junctional region of ciliary outer doublet microtubules: a model for treadmilling by lattice dislocation

Even in the presence of colchicine or Taxol(R), sea urchin embryonic cilia undergo substantial steady-state turnover, with a rate of tubulin incorporation approaching half that seen in full regeneration [Stephens: Mol Biol Cell 8:2187-2198, 1997]. Preliminary experiments suggest that tubulin incorporates differentially into the most stable portion of the outer doublet, the junctional protofilaments [Stephens: Cell Struct Funct 24:413-418, 1999]. To explore this possibility further, embryos of the sea urchin Tripneustes gratilla, a ciliary length inducible system [Stephens: J Exp Zool 269:106-115, 1994a], were pulse labeled with (3)H leucine during steady-state turnover or induced elongation, followed by regeneration in the presence of unlabeled leucine. Cilia were isolated by hypertonic shock and fractionated into detergent-soluble membrane plus matrix, thermally-solubilized microtubule walls, and insoluble 9-fold symmetric remnants of A-B junctional protofilaments plus associated architectural elements. The fractions were resolved by SDS-PAGE and the specific activity of alpha-tubulin was determined. In cilia undergoing turnover or elongation during an isotope pulse, the specific activity of tubulin in the junctional region approximated that of precursor membrane plus matrix tubulin but surpassed that of the tubule wall by a factor of approximately 1.5. In cilia regenerated during an isotope chase, the specific activity of junctional tubulin exceeded that of both the membrane plus matrix and the tubule wall by a similar factor. These data indicate that tubulin is preferentially incorporated into junctional protofilaments during steady-state turnover, induced elongation and regeneration. A model for directional incorporation based on surface lattice discontinuities in the outer doublet is proposed.

Tektins as structural determinants in basal bodies

Tektins, present as three equimolar 47-55 kDa protein components, form highly insoluble protofilaments that are integral to the junctional region of outer doublet microtubules in cilia and flagella. To identify and quantify tektins in other compound microtubules such as centrioles or basal bodies, a rabbit antiserum was raised against tektin filaments isolated from Spisula solidissima (surf clam) sperm flagellar outer doublets and affinity-purified with nitrocellulose blot strips of tektins resolved by SDS- or SDS-urea-PAGE. These antibodies recognized analogous tektins in axonemes of organisms ranging from ctenophores to higher vertebrates. Quantitative immunoblotting established that outer doublet tektins occur in a 1:17 weight ratio to tubulin. Cilia and basal apparatuses were prepared from scallop gill epithelial cells; cilia and deciliated cells were prepared from rabbit trachea. Tektins were detected by immunoblotting in basal body-enriched preparations while tektins were localized to individual basal bodies by immunofluorescence. Supported by greater fluorescence in basal bodies than in adjacent axonemes in tracheal cells, analysis of basal apparatuses demonstrated both a proportionately greater ratio of tektin to tubulin (approximately 1:13) and two distinct solubility classes of tektins, consistent with tektins comprising the B-C junction of triplets in addition to the A-B junction as in doublets.

Anatomy of the internal branch of the superior laryngeal nerve

The purpose of this study was to determine the length and distribution of the branches of the internal branch of the superior laryngeal nerve (ibSLN) and describe the initial afferent pathway for the laryngeal cough reflex (LCR). On 25 sides of 19 cadaver specimens, the ibSLN and its branches were dissected from the greater cornu of the hyoid to the mucosa of the larynx and laryngopharynx. The location of these terminal fibers were confirmed by direct observation and fiberoptic laryngoscopy. In 21 specimens, the ibSLN coursed 6.95+/-3.71 mm before piercing the thyrohyoid membrane and splitting into superior, middle, and inferior rami. Four specimens split proximal to the thyrohyoid membrane. The superior ramus distributed to the mucosa of the piriform recess. In this study the large, middle ramus was a new finding and distributed branches to the mucosa of the vestibule of the larynx, specifically the quadrangular membrane. The length of the ibSLN from the greater cornu to the end of the middle ramus at quadrangular membrane was 28.52+/-4.61 mm. The termination of these fibers were confirmed by observation and direct laryngoscopy. The middle ramus probably conveyed the afferent component of the laryngeal cough reflex. The inferior ramus did not distribute to the vestibular mucosa.

Molecular chaperones in cilia and flagella: implications for protein turnover

The mechanisms of protein incorporation and turnover in 9+2 ciliary axonemes are not known. Previous reports of an HSP70-related protein, first in Chlamydomonas flagella and then in sea urchin embryonic cilia, suggested a potential role in protein transport or incorporation. The present study further explores this and other chaperones in axonemes from a representative range of organisms. Two-dimensional gel electrophoresis proved identity between the sea urchin ciliary 78 kDa HSP and a constitutive cytoplasmic HSP70 cognate (pI = 5.71). When isolated flagella from mature sea urchin sperm were analyzed, the same total amount and distribution of 78 kDa protein as in cilia were found. Antigens of similar size were detected in ctenophore comb plate, molluscan gill, and rabbit tracheal cilia. Absent from sea urchin sperm flagella, TCP-1alpha was detected in sea urchin embryonic and rabbit tracheal cilia; the latter also contained HSP90, detected by two distinct antibodies. Tracheal cilia were shown to undergo axonemal protein turnover while tracheal cells mainly synthesized ciliary proteins. TCP-1alpha progressively appeared in regenerating embryonic cilia only as their growth slowed, suggesting a regulatory role in incorporation or turnover. These results demonstrate that chaperones are widely distributed ciliary and flagellar components, potentially related to axonemal protein dynamics.

Anesthesia for the superior laryngeal nerves and tartaric acid-induced cough

OBJECTIVE

The internal branch of the superior laryngeal nerve (ibSLN) conveys impulses for the laryngeal cough reflex, which protects the laryngeal aditus and prevents the development of aspiration pneumonia. The purpose of this study was to determine the effect of bilateral anesthesia of the ibSLN on the cough reflex after inhalation of a nebulized chemoirritant solution of tartaric acid.

DESIGN

Prospective, clinical investigation.

SETTING

Outpatient.

PARTICIPANTS

Nine healthy volunteers.

INTERVENTIONS

Bilateral injections of 2% lidocaine solution without epinephrine into the paraglottic space containing the ibSLN.

MAIN OUTCOME MEASURES

The tidal volume after inhalation of a nebulized 20% tartaric acid solution and forced vital capacity (FVC) were measured before and after injection. Data were analyzed using the Wilcoxon signed ranks, Mann-Whitney, and sign tests.

RESULTS

Complete anesthesia of the ibSLN abolished the laryngeal cough reflex. Postinjection tidal volumes were significantly lower than preinjection volumes (p<.01). The decrease in tidal volumes for six subjects with complete bilateral anesthesia was significantly larger than the decrease in tidal volumes for three subjects with partial anesthesia (p<.05). FVC in both the six subjects with complete bilateral anesthesia and the three subjects with partial anesthesia did not significantly change from preinjection to postinjection. None of the subjects in this study had complications or adverse respiratory sequelae.

CONCLUSION

Tartaric acid-induced cough may be useful in assessing the integrity of the laryngeal cough reflex after anesthesia or in patients with neurologic injury who are at risk of developing aspiration pneumonia. It may also be useful in making the decision whether to resume oral feeding.

Visual quantification of DNA double-strand breaks in bacteria

In this paper, we describe a method for the visualization of double-strand breaks in a single electrostretched Escherichia coli DNA molecule. We also provide evidence that electrostretched or migrated DNA under neutral microgel electrophoresis conditions is made up of individual chromosomes. Using the neutral microgel electrophoresis technique, DNA migration (stretching) was measured and the number of DNA double-strand breaks were counted following exposure of E. coli cells to 0, 12.5, 25, 50, or 100 rad of X-rays. The use of an intense fluorescent dye, YOYO and custom-made slides have helped us in visualizing individual bacterial DNA molecules. Bacterial DNA appears similar in structure compared to electrostretched DNA from human lymphocytes. We were able to detect changes in DNA migration (stretching) induced by an X-ray dose as low as 12.5 rad and an increase in the number of DNA breaks induced by a dose as low as 25 rad. The extent of DNA migration and number of breaks were directly correlated to X-ray dosage.

Assessing the laryngeal cough reflex and the risk of developing pneumonia after stroke: an interhospital comparison

BACKGROUND AND PURPOSE

We sought to evaluate the efficacy of testing the laryngeal cough reflex in identifying pneumonia risk in acute stroke patients.

METHODS

We performed a prospective study of 400 consecutive acute stroke patients examined using the reflex cough test (RCT) compared with 204 consecutive acute stroke patients from a sister facility examined without using the RCT. The binary end point for the study outcome was the development of pneumonia.

RESULTS

Of the 400 patients examined with the RCT, 5 developed pneumonia. Of the 204 patients examined without the RCT, 27 developed pneumonia (P<0.001). Three of the 27 patients died in the rehabilitation hospital of respiratory failure secondary to pneumonia. Seven others were transferred to the emergency department with acute respiratory distress. Power analysis for this comparison was 0.99. There were no other significant differences between the 2 groups.

CONCLUSIONS

A normal RCT after an acute stroke indicates a neurologically intact laryngeal cough reflex, a protected airway, and a low risk for developing aspiration pneumonia with oral feeding. An abnormal RCT indicates risk of an unprotected airway and an increased incidence of aspiration pneumonia. Alternate feeding strategies and preventive measures are necessary with an abnormal RCT. Clinical treatment algorithm and prescription of food, fluids, and medications are discussed on the basis of RCT results.

Assessing the laryngeal cough reflex and the risk of developing pneumonia after stroke

OBJECTIVE

To determine the effectiveness of a new reflex cough test, using nebulized tartaric acid, in the evaluation of the laryngeal cough reflex and the development of aspiration pneumonia.

STUDY DESIGN

In this two-phase study, the cough test assessed the cough reflex in 161 stroke subjects. Phase 1 was a double-blinded prospective study of 40 subjects scheduled to have both modified barium swallow and the reflex cough test. Phase 1 subjects with an abnormal cough test showed an increased pneumonia incidence, and therefore, phase 2 was not blinded. In phase 2, 121 subjects were evaluated using the cough test; 38 received a modified barium swallow. Test results were compared using the Fisher exact test.

RESULTS

A total of 131 subjects from both phases had a normal reflex cough test; none developed pneumonia (p < .01). Thirty subjects from both phases had abnormal reflex cough test results; 5 developed pneumonia. Modified barium swallow findings did not reliably indicate the risk for developing pneumonia. Specificity of a normal reflex cough test was 100%.

CONCLUSION

The reflex cough test reliably evaluated the laryngeal cough reflex and the associated risk of developing aspiration pneumonia in stroke patients. Testing the laryngeal cough reflex may significantly reduce morbidity, mortality, and costs in stroke patients.

Turnover of Tubulin in Ciliary Outer Doublet Microtubules

Previous pulse-chase labeling studies have shown that structural proteins incorporate into fully assembled sea urchin embryonic cilia at rates approaching those of full regeneration. When all background ciliogenesis was suppressed by taxol, the turnover of most proteins, including tubulin, continued. The present study utilized chemical dissection to explore the route of tubulin incorporation in the presence of taxol and also in steady-state cilia from prism stage embryos. Surprisingly, in cilia from untreated embryos, the most heavily labeled tubulin was found in the most stable portion of the doublet microtubles, the junctional protofilaments. With taxol, this preferential incorporation was suppressed, although control-level turnover still took place in the remainder of the doublet. This paradoxical result was confirmed by pulse-chase labeling and immediately isolating steady-state cilia, then isolating two additional crops of cilia regenerated, respectively, from pools of high and then decreased label. In each case, the level of label occurring in the tubulin from the junctional protofilaments, compared with that from the remainder of the doublet, correlated with the level of pool label from which it must exchange or assemble. These data indicate that ciliary outer doublet microtubules are dynamic structures and that the junctional region is not inert. Plausible mechanisms of incorporation and turnover of tubulin in fully-assembled, fully-motile cilia can now be assessed with regared to recent discoveries, particularly intraflagellar transport, distal tip incorporation, and treadmilling.

Electrophoretic resolution of tubulin and tektin subunits by differential interaction with long-chain alkyl sulfates

Tubulin dimers, formed from globular alpha and beta subunits, and the tektins, three equimolar alpha-helical proteins that form filaments, mutually associate to form the junctional regions of doublet and triplet microtubules. When evaluated by SDS-PAGE, the apparent molecular weights of these proteins can deviate substantially from their sequence molecular weights in a manner sensitive to both the source of SDS and the species of origin. The electrophoretic mobility of sperm tail flagellar tubulins and tektins from an echinoderm and a mollusc were studied systematically using detergent-free stacking and resolving gels with a running buffer containing pure sodium dodecyl sulfate augmented with fixed amounts of C10, C14, C16, or C18 alkyl sulfates. Although having no systematic effect on molecular weight standards, the presence of alkyl sulfates of increasing chain length progressively exaggerated the separation of tubulin subunits, similarly facilitated the separation of two normally comigrating tektins, yet minimally influenced the relative migration of adequately separated tektins. This phenomenon is most likely due to preferential binding of longer chain alkyl sulfates by specific hydrophobic regions of these otherwise similar proteins. The use of binary mixtures of pure alkyl sulfates, required in the running buffer alone, may prove useful for reproducibly separating other proteins that characteristically bind SDS anomalously.

Tartaric acid-induced cough and the superior laryngeal nerve evoked potential

The purpose of this study was to stimulate the laryngeal cough reflex using a nebulized, mild chemical irritant and to record an associated laryngeal evoked potential from the internal branch of the superior laryngeal nerve. The laryngeal evoked potential was obtained on ten normal subjects from the right internal branch of the superior laryngeal nerve. The electrodiagnostic setup included an active electrode placed just below the hyoid bone with a 4-cm separation and distal reference. A ground electrode was placed between the active and reference electrodes. The receptors and internal branch of the superior laryngeal nerve were stimulated by inhalation of a nebulized 20% solution of tartaric acid and normal saline. The time line was triggered by a pneumatic switch on initial inspiration of the nebulized tartaric acid. The electrodiagnostic settings were set at a sweep speed of 1 ms/division, a gain of 10 to 20 microV/division, and 20 to 2,000 filters. There were 132 variables recorded from the internal branch of the superior laryngeal nerve of the ten subjects. The mean peak distal latency was 1.66+/-0.42 ms with a 1.6 median, 1.6 mode, and 0.17 variance. The duration was 0.41 ms, and amplitude was 5.19+/-2.91 microV. In conclusion, the laryngeal evoked potential, the afferent component of the involuntary cough reflex, can be recorded from the internal branch of the superior laryngeal nerve after inhalation of tartaric acid-induced cough.

X-ray induced DNA double-strand breaks in human sperm

A methodology for quantifying DNA double-strand breaks in human sperm is described. Sperm from three healthy human donors on three separate days each were irradiated with 12.5, 25, 50 and 100 cGy X-rays. Linear dose-response effects were observed in migrated DNA from sperm nuclei when electrophoresed under neutral conditions. RNase and proteinase K treatments for longer duration were necessary, to decondense the chromatin and presumably to release the broken DNA for migration in the electrophoretic field in a dose-dependent manner. An increase in DNA migration was observed with as low as 12.5 cGy, but damage was observed in all samples at 25 cGy. No evidence of repair of these X-ray-induced DNA double-strand breaks was observed during a 2 h period.

Synthesis and turnover of embryonic sea urchin ciliary proteins during selective inhibition of tubulin synthesis and assembly

When ciliogenesis first occurs in sea urchin embryos, the major building block proteins, tubulin and dynein, exist in substantial pools, but most 9 + 2 architectural proteins must be synthesized de novo. Pulse-chase labeling with [3H]leucine demonstrates that these proteins are coordinately up-regulated in response to deciliation so that regeneration ensues and the tubulin and dynein pools are replenished. Protein labeling and incorporation into already-assembled cilia is high, indicating constitutive ciliary gene expression and steady-state turnover. To determine whether either the synthesis of tubulin or the size of its available pool is coupled to the synthesis or turnover of the other 9 + 2 proteins in some feedback manner, fully-ciliated mid- or late-gastrula stage Strongylocentrotus droebachiensis embryos were pulse labeled in the presence of colchicine or taxol at concentrations that block ciliary growth. As a consequence of tubulin autoregulation mediated by increased free tubulin, no labeling of ciliary tubulin occurred in colchicine-treated embryos. However, most other proteins were labeled and incorporated into steady-state cilia at near-control levels in the presence of colchicine or taxol. With taxol, tubulin was labeled as well. An axoneme-associated 78 kDa cognate of the molecular chaperone HSP70 correlated with length during regeneration; neither colchicine nor taxol influenced the association of this protein in steady-state cilia. These data indicate that 1) ciliary protein synthesis and turnover is independent of tubulin synthesis or tubulin pool size; 2) steady-state incorporation of labeled proteins cannot be due to formation or elongation of cilia; 3) substantial tubulin exchange takes place in fully-motile cilia; and 4) chaperone presence and association in steady-state cilia is independent of background ciliogenesis, tubulin synthesis, and tubulin assembly state.

Microgel electrophoresis: sensitivity, mechanisms, and DNA electrostretching

Based on the treatment of microgels to remove proteins, we speculate that proteins may be bound to DNA in the microgels even after electrophoresis. We speculate that some DNA single-strand breaks may be a reflection of these protein-DNA complexes. We suggest methods to limit such artifacts, and present data demonstrating a lymphocyte DNA double-strand break sensitivity of 12.5 rads and day-to-day reproducibility of microgel electrophoresis using these principles. Extending these principles, we describe DNA behavior during alkaline and neutral microgel electrophoresis based on observations of the stained DNA and its migration patterns. During microgel electrophoresis, individual DNA molecules behave as if anchored at one end while the other end is free to migrate in response to the electric field. We capitalize on this behavior by developing a neutral microgel method to stretch chromosomes.

Selective incorporation of architectural proteins into terminally differentiated molluscan gill cilia

Incubation of excised gills from the bay scallop Aequipecten irradians with 3H-leucine demonstrates that many ciliary structural proteins can attain a degree of labeling approaching that previously reported for sea urchin or surf clam embryos undergoing ciliary turnover or regeneration. This labeling is not a consequence of any predominant incorporation into new cilia at the meristematic growth tips of the gill since tissue regions of varying maturity incorporate label into the same proteins at similar levels, with the most mature region having the highest incorporation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorographic analysis of isolated cilia, separated into detergent-soluble membrane/matrix and detergent-insoluble 9+2 axoneme fractions, reveals that 1) tubulin in the membrane/matrix fraction is labeled whereas tubulin in the axoneme is not; 2) no labeled dynein heavy chains are seen in either fraction; 3) the most heavily labeled axonemal components do not appear to any significant extent in the membrane/matrix fraction; and 4) after thermal depolymerization of the microtubules, nearly all labeled proteins reside in the in-soluble ninefold ciliary remnant, the most prominent being tektin A, an integral component of outer doublet microtubules. Further fractionation of the remnant with sarkosyl-urea to produce tektin filaments demonstrates two solubility classes of tekin A, only the more soluble of which is labeled. Very similar selective architectural protein labeling patterns have been reported for steady-state cilia of sea urchin embryos, and this may indicate a widespread turnover or exchange mechanism characteristic of cilia heretofore considered static.

Substance P and neurokinin A metabolism by cultured human skeletal muscle myocytes and fibroblasts

A recent study determined that cultured human skeletal muscle adult myoblasts, myotubes, and fibroblasts degraded angiotensins and kinins via neutral endopeptidase-24.11 (NEP-24.11: EC 3.4.24.11) and aminopeptidase N (APN: EC 3.4.11.2). Due to the possible importance of other peptides to skeletal muscle blood flow and function, the present study looked specifically at the metabolism of the neurokinins substance P (SP) and neurokinin A (NKA) by skeletal muscle peptidases. The results show that SP is degraded not only by NEP-24.11, but also sequentially by dipeptidyl(amino)peptidase IV (DAP IV: EC 3.4.14.5)/APN. NKA is unaffected by DAP IV but is metabolized by NEP-24.11 and APN. NEP-24.11 was inhibited by phosphoramidon (IC50 = 80 nM), thiorphan and ZINCOV, DAP IV by diprotin A (IC50 = 8 microM), and APN by amastatin (IC50 = 50 nM) and bestatin (IC50 = 100 microM). Skeletal muscle myocyte and fibroblast metabolism of SP and NKA may regulate local skeletal muscle vascular and extravascular functions including SP- and NKA-mediated nerve-induced vasodilation. Inhibition of both NEP-24.11 and DAP IV/APN may increase skeletal muscle blood flow and decrease peripheral vascular resistance via potentiation of local neurokinin levels.

Thyronines and probucol inhibition of human capillary endothelial cell-induced low density lipoprotein oxidation

Oxidized lipoproteins have been implicated as important factors in the pathogenicity of atherosclerosis. Thus, antioxidants play a significant role in inhibiting a critical step in atheroma progression. Previously, we demonstrated that thyronine analogs inhibit Cu(2+)-induced low density lipoprotein (LDL) oxidation. In the present study, we examined the effect of thyronine analogs on endothelial cell (EC)-induced LDL oxidation. LDL was incubated with or without EC in the presence or absence of various concentrations of thyronine, vitamin C, or probucol at 37 degrees in a humidified atmosphere (95% air, 5% CO2). Thyronine analogs, probucol, and vitamin C inhibited EC-induced LDL oxidation in a concentration-dependent manner. The concentration of each agent (microM) producing 50% inhibition (IC50) of EC-induced LDL oxidation for thiobarbituric acid reactive substances (TBARS) and electrophoretic mobility, respectively, was as follows: 0.294 and 0.417 for levothyroxine (L-T4); 0.200 and 0.299 for L-triiodothyronine (L-T3); 0.125 and 0.264 for dextro-thyroxine (D-T4); 0.203 and 0.304 for reversed triiodothyronine (rT3); 1.02 and 1.44 for probucol; and 13.6 and 14.9 for vitamin C. Thyroid binding globulin (TBG) inhibited EC-induced LDL oxidation; further, thyronines bound to TBG exhibited more antioxidant activity than unbound thyronines. Pretreatment of EC with any of the thyronines decreased the ability of EC to oxidize LDL. Also, our results showed that a synergistic interaction exists between vitamin C and T4 in the inhibition of EC-induced LDL oxidation. The T4 and TBG concentrations that inhibited LDL oxidation were in the physiological range. We conclude that T4, like the pharmacological agent probucol, reduces oxidative modification of LDL and thus may act as a natural inhibitor of atherogenesis.

Cultured AIDS-related Kaposi's sarcoma (AIDS-KS) cells demonstrate impaired bioenergetic adaptation to oxidant challenge: implication for oxidant stress in AIDS-KS pathogenesis

Despite its recognition as the most prevalent HIV associated cancer, speculation still abounds regarding the pathogenesis of AIDS-related Kaposi's sarcoma (AIDS-KS). However, it has been established that both cytokines, e.g. IL-6, and HIV-associated products, e.g., Tat, are integral in AIDS-KS cellular proliferation. Further, both experimental and clinical evidence is accumulating to link reactive oxygen intermediates (ROI) with both cytokine induction (primarily via nuclear factor-kappa B[NF-kappa B] dependent routes) as well as the subsequent cytokine, tumor necrosis factor alpha (TNF alpha) stimulation of HIV replication. Features of AIDS-KS patients, such as retention of phagocytes, presence of sustained immunostimulation, and a frequent history of KS lesions arising at traumatized sites, make oxidant stress a viable clinical factor in AIDS-KS development. Time course nucleotide profile analyses show that AIDS-KS cells have an inherent, statistically significant, biochemical deficit, even prior to oxidant stress, due to 1) a more glycolytic bioenergetic profile, resulting in lower levels of high energy phosphates (impairing capacity for glutathione [GSH] synthesis and DNA repair); 2) lower levels of NADPH (compromising the activities of GSSG reductase and peroxidase function of catalase); and 3) reduced levels of GSH (impeding both GSH peroxidase and GSH-S-transferases). Following exposure to physiologically relevant levels of H2O2, only the human microvascular endothelial cells (a putative AIDS-KS progenitor cell) responded with bioenergetic adaptations that reflected co-ordination of energy generating and cytoprotective pathways, e.g., retention of the cellular energy charge, increased NAD+, and an accentuation of the ATP, NADPH, and total adenine nucleotide differences relative to AIDS-KS cells. Also, some of the AIDS-KS strains retained intracellular GSSG subsequent to oxidant challenge, inviting the formation of deleterious protein mixed disulfides. While the results of our study address some AIDS-KS issues, they also raise an etiological question, i.e., Does the inability to tolerate oxidant stress arise in conjunction with AIDS-KS neoplastic development, or is it pre-existing in the population at risk? Regardless, use of antioxidant therapy (low risk/ potentially high benefit) in both the "at risk" population as well as in those individuals with active disease may prove a useful preventative and/or treatment modality.

Correlation between AIDS-related Kaposi sarcoma histological grade and in vitro behavior: reduced exogenous growth factor requirements for isolates from high grade lesions

Kaposi sarcoma, the most common AIDS-associated malignancy, affects 10-30% of all AIDS patients. To date, research into the biological characteristics of AIDS-related Kaposi sarcoma (AIDS-KS) derived cell lines has been based on cultures established from skin explants or pleural effusions/peritoneal fluids. We have established several AIDS-KS lines from biopsy confirmed oral mucosal and epidermal AIDS-KS lesions and have found a correlation between AIDS-KS lesional grade and in vitro cellular growth characteristics. In comparison to epidermal AIDS-KS lesions, mucosal AIDS-KS lesions frequently possessed both a more advanced histologic grade and demonstrated a greater capacity to proliferate in minimal medium. We report the ability of AIDS-KS isolates from high grade lesions to sustain proliferation (greater than 60 population doubling levels) in medium not supplemented with endothelial cell growth supplement and/or cytokine rich conditioned medium. These findings indicate that AIDS-KS cells isolated from high grade lesions have reduced requirements for exogenously provided growth supplements, and suggest that increased autologous cytokine production accompanies AIDS-KS lesional progression.

Transcriptional control of tektin A mRNA correlates with cilia development and length determination during sea urchin embryogenesis

Previous studies have shown that tektin A, one of three integral filamentous protein components of outer doublet microtubules, is synthesized in sea urchins in an amount correlating to the length of embryonic cilia initially assembled or experimentally regenerated. To investigate further the molecular mechanism for the regulation of tektin synthesis, tektin cDNA clones were used to assess mRNA levels during ciliogenesis, zinc-induced animalization, deciliation-induced regeneration and theophylline-induced elongation. Possibly involved in centriole replication, low, near-constant levels of mRNA for all three tektins are present in the unfertilized egg and during cleavage stages. Preceded by new synthesis of tektin B and C mRNAs, tektin A mRNA is up-regulated during ciliogenesis, but only tektin A mRNA levels correlate directly with ciliary length in animalized embryos; the others augment larger, non-limiting pools of tektins B and C. Tektin mRNAs decrease to steady-state levels after ciliogenesis, but are up-regulated again when the embryos are deciliated, correlating with the length of cilia to be deployed. In a species where a 3-fold ciliary length increase can be induced by theophylline treatment of zinc-arrested embryos, the mRNAs accumulate to proportionately higher levels during arrest but are not translated until induction, whereupon they decrease inversely with ciliary elongation. This suggests transcriptional control with respect to mRNA amounts but post-transcriptional control with respect to the expression of this phenotype.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of constitutive cytokine release in high and low histologic grade AIDS-related Kaposi's sarcoma cell strains and in sera from HIV+/KS+ and HIV+/KS- patients

Kaposi's sarcoma (KS) is both an AIDS-defining disease and the most common HIV-associated malignancy. A cytokine-mediated pathogenesis for AIDS-KS is implicated because AIDS-KS-derived cell strains both respond to and express a variety of cytokines. We have reported the establishment of several (n = 18) AIDS-KS cell strains and determined that reduced exogenous growth factors are necessary to sustain proliferation in isolates from high histologic grade KS lesions. This current investigation explored the possibility that there are histologic grade-associated differences in either the qualitative and/or quantitative constitutive release of AIDS-KS growth stimulatory cytokines. Our findings showed that the incorporation of HTLV-II cytokine-rich conditioned media induced both qualitative and significant quantitative cytokine release, suggesting that exogenous growth promoters stimulate constitutive cytokine release. ELISA of our AIDS-KS cell strains demonstrated constitutive release of IL-6 (seven of seven), FGF-2 (five of seven), GM-CSF (three of seven), and IL-1 beta (one of seven). None of our AIDS-KS cell strains constitutively released detectable levels of Onco-M, IL-4, PDGF, TNF-alpha, or TNF-beta. In addition, we report that the method of cytokine result quantitation significantly affects reported cytokine levels. We determined that there was no significant histologic grade-dependent difference in the constitutive release of soluble cytokines by in vitro grown cultures of AIDS-KS cells. The presence of HIV influenced the sera cytokine profiles by elevating IL-6 and decreasing PDGF concentrations of HIV+ individuals relative to HIV- healthy controls. However, the presence of KS was not associated with unique serum cytokine profiles, because no differences were noted in comparisons of HIV+/KS+ versus HIV+/KS- individuals. Our findings suggest that the local environment is key in modulating AIDS-KS cytokine expression and that KS growth-promoting factors function at the local or paracrine, not the systemic, level. In conclusion, our previous results demonstrated a histologic grade-associated difference in the in vitro growth capacity of AIDS-KS cells; with high histologic grade isolates displaying a marked growth advantage during culture in minimally supplemented media. Findings from this current study reveal that although the potential for a constitutive growth loop exists in the high-grade isolates, it is not reflected in the free levels of soluble cytokines secreted into the culture medium.

Ciliogenesis in sea urchin embryos--a subroutine in the program of development

One major milestone in the development of the sea urchin embryo is the assembly of a single cilium on each blastomere just before hatching. These cilia are constructed both from pre-existing protein building blocks, such as tubulin and dynein, and from a number of 9 + 2 architectural elements that are synthesized de novo at ciliogenesis. The finite or quantal synthesis of certain key architectural proteins is coincident with ciliary elongation and proportional to ciliary length. Upon deciliation, the synthesis of architectural proteins occurs anew, a new cilium grows, and the stores of various building blocks are replenished. This routine of coordinated ciliary gene expression may be replayed experimentally many times without delaying normal development. The ability to regenerate cilia has allowed elucidation of these various protein synthetic relationships and has led to the discovery of the pathways by which membrane-associated tubulin and axoneme-associated architectural proteins are conveyed into the highly compartmentalized growing cilium. The sea urchin embryo thus provides a very convenient model system for studies of ciliary assembly and maintenance, coordinate gene expression and membrane dynamics.

Dynein inner arm heavy chain identification in cAMP-activated flagella using class-specific polyclonal antibodies

While studying cAMP-dependent dynein alpha-heavy chain phosphorylation, we found previously [Stephens and Prior, 1992: J. Cell Sci. 103:999-1012] that high salt extraction of sperm flagella from the mussel Mytilus edulis or the clam Spisula solidissima removed most visible dynein arms, accompanied by an amount of Mg+2-ATPase that correlated with the mass of dynein alpha- and beta-heavy chains removed. However, although almost devoid of ATPase activity, such extracted axonemes retained one third of the heavy chain mass as two sets of electrophoretically-distinct, vanadate-cleavable, non-phosphorylated proteins. To explore the nature of these dynein-like proteins, antibodies to the alpha- and beta-heavy chains were blot affinity-purified from a rabbit antiserum raised against gradient-purified Spisula 18-20S flagellar outer arm dynein. Although able to recognize common epitopes of the opposite chain type, neither the alpha- nor the beta-heavy chain antibody recognized the tightly-bound proteins in either species, proving that they are immunologically distinct. While the beta-antibody recognized its heavy chain homolog in gill cilia, the alpha-antibody did not, demonstrating immunological distinction between flagellar and ciliary dynein alpha-heavy chains. Immunization of a mouse with nitrocellulose strips containing one of the two tightly-bound Spisula flagellar proteins produced an antiserum that cross-reacted with each tightly-bound protein in both species and also recognized alpha- and beta-heavy chains. The anti-molluscan serum cross-reacted strongly with sea urchin sperm flagellar dynein B-, C-, and D-bands, considered to be inner arm components, but not with sea urchin outer arm alpha- or beta-heavy chains. These data indicate that the electrophoretically and immunologically distinct, tightly-bound proteins of molluscan flagella are inner arm dynein heavy chains.

Human microvascular endothelial cell-extracellular matrix interaction in cellular growth state determination

We introduce two methods, both of which are based on cellular-extracellular matrix interaction, which will facilitate the study of human microvascular endothelial cells. One method describes the means to obtain a G1 population baseline in human microvascular endothelial cells. Because of the contribution of the extracellular matrix in endothelial cell growth, synchronization in G1 was possible only after the incorporation of angiostatic levels of heparin and hydrocortisone into the extracellular matrix. In the second method, we demonstrate that selective perturbation of human microvascular endothelial cell-extracellular matrix interactions results in the induction of a transitional growth state, between proliferative and differentiated growth states, in human microvascular endothelial cells. In the functional, microtubule formation assays, transitional growth state endothelial cells display rates that are indermediate between those obtained from differentiated and proliferative endothelial cells. Our results demonstrate the importance of the human microvascular endothelial cell-extracellular matrix interaction in the determination of cellular growth state. Our findings also imply that responsiveness of microvascular endothelial cells to their cellular-extracellular matrix environs is highest during the differentiated growth state.

Angiotensin and bradykinin metabolism by peptidases identified in cultured human skeletal muscle myocytes and fibroblasts

Angiotensin (ANG) and kinin metabolizing enzymes, angiotensin-converting enzyme (ACE; EC 3.4.15.1), neutral endopeptidase-24.11 (NEP-24.11; EC 3.4.24.11), and aminopeptidase M (AmM; EC 3.4.11.2), have recently been identified in a purified skeletal muscle glycoprotein fraction. We have analyzed the cellular localization of these enzymes. In cultured human skeletal muscle adult myoblasts, myotubes, and fibroblasts, kinins and angiotensins were metabolized by NEP-24.11 and AmM but not by ACE. NEP-24.11 degraded ANG II, ANG III. and bradykinin (BK) and converted ANG I to the active metabolite ANG(1-7). ANG III was converted to the novel ANG IV metabolite [des-Arg1]ANG III by AmM. These data suggest that, due to their abundance in the body, skeletal muscle myocytes and fibroblasts may play a major role in modulation of the systemic and local effects of angiotensins and kinins. This role could be particularly important in individuals receiving treatment with ACE inhibitors.

Cultured AIDS-related Kaposi's sarcoma cells retain a proliferative bioenergetic profile but demonstrate reduced cytoprotective capabilities

Features of AIDS-related Kaposi's sarcoma (AIDS-KS), such as the multifocal presentation at mucosal and epidermal sites subjected to trauma, suggest that AIDS-KS is initially a reactive hyperplasia that subsequently progresses to a neoplasia. It is recognized that there is an association between sustained inflammatory states and the subsequent development of neoplasia (e.g., ulcerative colitis/colonic adenocarcinoma). Furthermore, patients who develop AIDS-KS experience both a constant immune stimulation due to sustained high levels of virus-induced cytokines and, because of a sparing effect on their phagocytic cells, retention of the phagocytic inflammatory response. A component of phagocytic activation is the initiation of the oxidative burst, resulting in the generation of reactive oxygen species (ROS), which can be mutagenic to host cells if released beyond the phagolysosome and not inactivated. Our results demonstrate that cultured AIDS-KS cells possess decreased cytoprotective capabilities. Relative to either dermal fibroblasts, or human microvascular endothelial cells (HMECs), AIDS-KS cells contained significantly lower levels of glutathione, a tripeptide integral in both cytoprotection and maintenance of cellular thiol status. While HMECs increased catalase activity during culture in the cytokine-rich KS milieu (control medium supplemented with conditioned medium from MOT, an HTLV II-infected cell line), AIDS-KS cells demonstrated reduced catalase function under these conditions. Furthermore, HMEC cultures showed an inherent biochemical responsiveness, by increasing catalase activity following exposure to exogenous H2O2. In contrast, the catalase activity of AIDS-KS cells decreased following H2O2 challenge. Our results show that an inherent deficiency in cellular cytoprotection is present in AIDS-KS cells and suggest that oxidant stress may function in the development and progression of AIDS-KS.

Modifications of alkaline microgel electrophoresis for sensitive detection of DNA damage

The alkaline microgel electrophoresis technique was modified to achieve a substantial increase in sensitivity for the detection of radiation-induced DNA damage in human lymphocytes. This increased sensitivity was achieved through: (1) the addition of free radical scavengers to the electrophoresis solution to reduce DNA damage generated during alkaline unwinding and electrophoresis; (2) the modification of the electrophoresis unit to achieve a more uniform electric field; (3) the use of YOYO-1, a DNA dye, producing fluorescence 500-fold more intense than ethidium bromide; and (4) the introduction of an image analysis system for the quantitation of DNA migration. In addition to increasing sensitivity, these modifications have increased the speed with which observations can be quantified, and improved reproducibility from experiment to experiment. In human lymphocytes, these modifications have resulted in an increased sensitivity of several fold, allowing the detection of DNA damage in the range of 50 mGy. This increased sensitivity for the detection of DNA damage should extend the utility of this technique.

Rapid induction of a hyperciliated phenotype in zinc-arrested sea urchin embryos by theophylline

Zinc ions, present since fertilization, will arrest embryos of the sea urchin Tripneustes gratilla at the hatched blastula stage, but such embryos lack long cilia, the usual characteristic of animalized embryos. Eventually these embryos will express a minimal long cilia phenotype, with a mean population < 1.4 times that of control blastulae, but only after contemporaneous control embryos gastrulate. Theophylline will rapidly but minimally animalize embryos when added after hatching, but its inductive ability decreases as the embryos gastrulate. Theophylline-animalized embryos produce cilia whose mean population length is > 1.5 times that of control blastulae. At any point from the time of hatching up until control complete gastrulation, theophylline added to zinc-arrested embryos will induce a hyperciliated phenotype with a mean population length nearly 3 times that of control blastulae. The elongation of cilia is immediate and significantly exceeds the rate of normal ciliary regeneration. Initially requiring the presence of theophylline, the hyperciliated phenotype becomes stable as control embryos begin gastrulation and, when deciliated, the induced embryos will regenerate hyperlong cilia in the absence of theophylline. The time dependence for both induction and phenotype stability would suggest that certain timing mechanisms are still operative in zinc-arrested embryos. This inducible system should facilitate studies of length control during ciliary elongation and regeneration.

Environmental induction of tumor phenotype in a putative Kaposi sarcoma progenitor cell

Many features of AIDS-related Kaposi sarcoma (AIDS-KS), e.g., multifocal lesional presentation at sites perfused by the microvasculature, suggest that AIDS-KS is initially a hyperplasia that subsequently progresses to a neoplasia. We propose that the unique AIDS environment, which contains high levels of circulating factors such as viral cytokines, is key in initiating the KS lesion. Further, we maintain that due to their physiological function, human microvascular endothelial cells (HMECs) are both likely target cells for the AIDS-related cytokines, and are putative AIDS-KS progenitor cells. Previously, we have shown that as a component of HMEC transition between proliferative and differentiated growth, HMECs modulate their nucleotide and glutathione levels. After attaining contact inhibition, HMECs enter a state of differentiation, which is characterized by cellular entrance into a G0, quiescent growth state, a decrease in cellular bioenergetic profiles, and spontaneous formation of microtubules. In contrast, when cultured in a "KS milieu", HMECs fail to differentiate. Instead, the "KS milieu" cultured cells assume a "growth relaxed" phenotype and demonstrate a lack of contact inhibition, loss of anchorage dependence, and retention of a "proliferative" bioenergetic profile despite culture confluence. Our results imply both that HMECs are responsive to AIDS-related cytokines, and that the local environment is key to instigating a relaxation of cellular growth controls.

Tubulin and tektin in sea urchin embryonic cilia: pathways of protein incorporation during turnover and regeneration

Axonemal precursor tubulin is the major protein component of the detergent-soluble membrane/matrix fraction of sea urchin embryonic cilia. Its unusual abundance may reflect the rapid turnover of these cilia, a process that is further documented here. However, whether during induced regeneration or normal turnover and growth, most other newly synthesized axonemal proteins are not detectable in the membrane/matrix fraction, raising the question of how non-tubulin precursors transit the growing cilium to the distal tip where assembly is generally thought to occur. Three potential explanations were considered: (1) the assembly of these components is proximal; (2) their relative concentration is too low to detect; or (3) tubulin alone is conveyed via a membrane/matrix pathway while most other axonemal proteins are transported in association with the axoneme. Light microscope autoradiography of axonemes pulse-chase labeled with [3H]leucine showed relatively uniform labeling, with no evidence for proximal incorporation. Fully grown cilia and cilia at early stages of regeneration were isolated from labeled embryos, fractionated into membrane/matrix, axonemal tubulin and architectural remnant components, and their labeled protein compositions were compared. Heavily labeled axonemal proteins, most notably the integral microtubule doublet component tektin-A, were not detected in the membrane/matrix fraction of emerging cilia, even though nearly half of the total ciliary tubulin appeared in that fraction, arguing against membrane-associated or soluble matrix transit for the architectural proteins at low concentrations. However, after thermal fractionation of axonemes from growing cilia, labeled proteins characteristic of the architectural remnant dominated the solubilized microtubule fraction, supporting axoneme-associated transport of the non-tubulin proteins during growth, in contrast to a membrane/matrix pathway for tubulin.

Ohioensins and pallidisetins: novel cytotoxic agents from the moss Polytrichum pallidisetum

Bioassay-directed fractionation of an EtOH extract of the moss Polytrichum pallidisetum (Polytrichaceae) led to the isolation of three novel benzonaphthoxanthenones, 1-O-methylohioensin B [6], 1-O-methyldihydroohioensin B [7] and 1,14-di-O-methyldihydroohioensin B [8], and two novel cinnamoyl bibenzyls, pallidisetin A [9] and pallidisetin B [10]. Their structures and relative stereochemistry were established by spectral analyses and chemical correlation. Compounds 6-10 exhibited cytotoxic activity against the human tumor cell lines RPMI-7951 melanoma and U-251 glioblastoma multiforme. These two types of compounds could hypothetically be derived from cinnamic acid and bibenzyls through different biogenetic pathways.

Metabolism of substance P and neurokinin A by human vascular endothelium and smooth muscle

Analysis of SP and NKA metabolism by human vascular endothelium, relative to that in human plasma, identified integrative, multiple pathways for the processing of circulating SP (but not NKA) by angiotensin-converting enzyme (ACE; EC 3.4.15.1), dipeptidyl(amino)peptidase IV (DAP IV; EC 3.4.14.5), and aminopeptidase M (AmM; EC 3.4.11.2). In contrast, SP and NKA, which may diffuse into or be neurally released within the vessel wall, were both metabolized by smooth muscle neutral endopeptidase-24.11 (NEP-24.11; EC 3.4.24.11). Collectively, these studies indicate peptide-specific and site-specific differential processing of SP and NKA by human plasma and vasculature.

Modulation of human microvascular endothelial cell bioenergetic status and glutathione levels during proliferative and differentiated growth

During angiogenesis, formerly differentiated human microvascular endothelial cells (HMECs) return to a proliferative growth state. Many fundamental questions regarding HMEC function, such as how HMECs adapt to changes in bioenergetic requirements upon return to proliferative growth, remained unanswered. In this study, we evaluated whether modifications in HMEC bioenergetic profiles and glutathione (GSH) levels accompanied the cellular transition between differentiated and proliferative growth. To provide insight into the continuum of cellular adaptations that occur during this transition, we used a method recently developed in our laboratory that induces a state of morphological and functional predifferentiation in HMECs. Cellular morphology, in conjunction with flow cytometric DNA analyses and HMEC functional assays (the directed migration and intercellular association involved in microtubule formation) were employed to validate the HMEC culture state of growth. Analysis of the HPLC nucleotide profiles disclosed several findings common to all culture growth states. These uniform findings, e.g., cellular energy charges > 0.90, and highly reduced redox states, revealed that cultured HMECs maintain high rates of oxidative metabolism. However, there were also significant, culture growth state related differences in the nucleotide profiles. Proliferative HMECs were shown to possess significantly higher (relative to both large vessel endothelial cells, and differentiated HMECs) levels of GSH and specific nucleotides which were related with a return to the active cell cycle-ATP, GTP, UTP, and CTP, and NADPH. Further, the nucleotide profiles and GSH levels of the predifferentiated HMECs were determined to be intermediate between levels obtained for the proliferative and differentiated HMECs. The results of this study demonstrate that the capacity to modulate their cellular bioenergetic status during growth state transitions is one of the adaptations that enable HMECs to retain a growth state reciprocity. In addition, our findings also show that HMECs, especially during the proliferative growth state, are biochemically distinct from endothelial cells harvested from large vessels, and therefore suggest that HMECs are the cells of choice to employ when studying diseases that affect the human microvasculature.

Protection of ROC-1 hybrid glial cells by polyethylene glycol following ATP depletion

Oligodendroglia-glioma hybrid cells (ROC-1) subjected to inhibition of glycolytic and oxidative ATP synthesis undergo a sequence of changes, including ATP depletion, parallel processes of cell swelling and blebbing, and finally plasma membrane disruption and cell death. The morphological and biochemical changes that follow ATP depletion were studied in the presence and absence of polyethylene glycol (M(r) 8,000), a nonpermeant oncotic agent. Polyethylene glycol prevented cell swelling and membrane blebbing. It significantly delayed, but did not prevent, the release of lactate dehydrogenase into the medium; it did not affect the fall in [ATP]. These results suggest that osmotic cell swelling may be a contributing factor in the loss of cell viability when ROC-1 cells are depleted of ATP.

Dynein from serotonin-activated cilia and flagella: extraction characteristics and distinct sites for cAMP-dependent protein phosphorylation

Serotonin, an activator of adenylate cyclase, stimulates motility in molluscan gill cilia and sperm flagella. To determine and compare potential targets of cAMP action, dynein was prepared from the lateral gill.cilia and sperm flagella of the mussel Mytilus edulis and the clam Spisula solidissima. In the flagella of both species, high-salt extraction removes about half of the ATPase activity, half of the alpha and beta heavy chains, and the outer arms. The dynein from both species sediments at 18–20 S, contains two or three intermediate chains, and three light chains. High-salt plus detergent removes most of the remaining dynein ATPase, alpha and beta heavy chains, and inner arms, also yielding a stable 18–20 S particle. In gill cilia of both species, high-salt extraction removes only 12–18% of the ATPase, up to 1/3 of the alpha heavy chains, an equivalent amount of beta heavy chain, and a subset of the outer arms. The dynein sediments at 18–20 S and, in Spisula, the heavy, intermediate, and light chains precisely co-sediment. High-salt plus detergent removes another 1/3 of the alpha heavy chains, an equivalent amount of beta heavy chain, and the remaining outer arms. The ATPase sediments mainly as a 13–14 S form showing considerable dissociation of co-sedimenting intermediate and light chains. The inner arms and at least half of the ciliary dynein ATPase activity remain unextractable, corresponding in mass mainly to an apparent beta heavy chain that is vanadate-cleavable. Cyclic AMP-dependent, calcium-independent phosphorylation takes place on specific dynein light chains in cilia but on only the dynein alpha heavy chain in flagella. Pre-activation of the flagella prevents subsequent addition of labeled phosphate. Phosphorylation has no effect on the steady-state ATPase properties. The single phosphate added to the flagellar alpha chain is located within the LUV1 vanadate photocleavage fragment. Considering the probable locus of the light chains and the site of the alpha heavy chain phosphorylation, both beyond the active site and toward the base of the molecule, these distinct phosphorylations may regulate dynein action by modulating arm flexibility or interaction.

Sensitivity of human glioma and brain cells to natural killer cell lysis. Effects of serum concentration, epidermal growth factor, and time in culture

Using an in vitro monolayer natural killer (NK) cytolysis assay, the authors examined the effects of serum concentration and epidermal growth factor (EGF) on sensitivity to NK cytolysis. It was found that target cells cultured in high concentrations of serum (10% fetal bovine serum (FBS)) had higher cytotoxicity levels than those in low serum concentrations (0% to 0.5% FBS). Exposure of target cells to EGF had no effect on their sensitivity to NK cytolysis. Both glioma cell lines showed decreased NK cell sensitivity with longer times in culture. The results of cytofluorometric studies on these cell lines indicate that the differences in NK cell sensitivity may reflect the growth fraction of the target population and that a population with a higher proportion of cycling cells is more susceptible to lysis by NK cells. Whether it is possible to separate the proliferative rate of these cells from their NK cell sensitivity is unknown, but worthy of consideration.

Tubulin in sea urchin embryonic cilia: post-translational modifications during regeneration

Tubulin is the major protein found in the membrane/periaxonemal matrix fraction of mature sea urchin embryonic cilia but its distribution and possible function during ciliary assembly are unknown. Hypertonic salt may be used to deciliate the embryos, allowing synchronous regrowth of cilia and subsequent deciliation of the regenerating embryos at various times. During the earliest stages of regeneration, the amounts of tubulin in the axoneme and membrane/matrix fractions are nearly equal, but the proportion of tubulin in the axoneme fraction increases coincident with the quasi-linear growth phase while the membrane/matrix tubulin remains constant. Antibodies to tyrosinated and detyrosinated alpha-tubulin show that both the membrane/matrix and axonemal tubulin fractions are primarily unmodified (i.e. tyrosinated) at the earliest stages of regeneration but are progressively and equally detyrosinated coincident with regeneration, approaching a final level of 50% C-terminal Glu. A monoclonal antibody to acetylated alpha-tubulin reveals that both tubulin fractions are equally and maximally acetylated at relatively early stages of regeneration. In contrast, three-times-repolymerized tubulin from either unfertilized eggs or midgastrula embryos is primarily tyrosinated (greater than 97%) and not detectably acetylated. These data suggest that membrane/matrix tubulin is a precursor to axonemal tubulin and that acetylation and detyrosination may be involved in partitioning tubulin among cytoplasmic, ciliary membrane/matrix, and 9 + 2 compartments.