More surprises in the global greenhouse: Human health impacts from recent toxic marine aerosol formations, due to centennial alterations of world-wide coastal food webs.

Reductions of zooplankton biomasses and grazing pressures were observed during overfishing-induced trophic cascades and concurrent oil spills at global scales. Recent phytoplankton increments followed, once Fe-, P-, and N-nutrient limitations of commensal diazotrophs and dinoflagellates were also eliminated by respective human desertification, deforestation, and eutrophication during climate changes. Si-limitation of diatoms instead ensued during these last anthropogenic perturbations of agricultural effluents and sewage loadings. Consequently, ~15% of total world-wide annual asthma trigger responses, i.e. amounting to ~45 million adjacent humans during 2004, resulted from brevetoxin and palytoxin poisons in aerosol forms of western boundary current origins. They were denoted by greater global harmful algal bloom [HAB] abundances and breathing attacks among sea-side children during prior decadal surveys of asthma prevalence, compiled here in ten paired shelf ecosystems of western and eutrophied boundary currents. Since 1965, such inferred onshore fluxes of aerosolized DOC poisons of HABs may have served as additional wind-borne organic carriers of toxic marine MeHg, phthalate, and DDT/DDE vectors, traced by radio-iodine isotopes to potentially elicit carcinomas. During these exchanges, as much as 40% of mercury poisonings may instead have been effected by inhalation of collateral HAB-carried marine neurotoxic aerosols of MeHg, not just from eating marine fish. Health impacts in some areas were additional asthma and pneumonia episodes, as well as endocrine disruptions among the same adjacent humans, with known large local rates of thyroid cancers, physician-diagnosed pulmonary problems, and ubiquitous high indices of mercury in hair, pesticides in breast milk, and phthalates in urine.

Prospective study of risk factors for suicidal behavior in individuals with anxiety disorders.

BACKGROUND: Anxiety disorders are very common and increase risk for suicide attempts. Little is known about predictors of increased risk specifically among individuals with anxiety disorders. The purpose of this study was to investigate whether specific anxiety disorders and other co-morbid psychiatric disorders, physical health, or work or social functioning increased the future likelihood of a suicide attempts among individuals with anxiety disorders. Method In this prospective study, 676 individuals with an anxiety disorder were followed for an average of 12 years. RESULTS: As hypothesized, we found that post-traumatic stress disorder, major depressive disorder (MDD), intermittent depressive disorder (IDD), epilepsy, pain, and poor work and social functioning all predicted a shorter time to a suicide attempt in univariate analyses. In multivariate analyses, baseline MDD and IDD were independent predictors of time to suicide attempt, even when controlling for a past history of suicide attempt. No specific anxiety disorder was an independent predictor of time to attempt in this anxiety-disordered sample. Adding baseline physical health variables and social functioning did not improve the ability of the model to predict time to suicide attempt. CONCLUSIONS: Mood disorders and past history of suicide attempts are the most powerful predictors of a future suicide attempt in this sample of individuals, all of whom have an anxiety disorder.

Red tides in the Gulf of Mexico: Where, when, and why?

[1] Independent data from the Gulf of Mexico are used to develop and test the hypothesis that the same sequence of physical and ecological events each year allows the toxic dinoflagellate Karenia brevis to become dominant. A phosphorus-rich nutrient supply initiates phytoplankton succession, once deposition events of Saharan iron-rich dust allow Trichodesmium blooms to utilize ubiquitous dissolved nitrogen gas within otherwise nitrogen-poor sea water. They and the co-occurring K. brevis are positioned within the bottom Ekman layers, as a consequence of their similar diel vertical migration patterns on the middle shelf. Upon onshore upwelling of these near-bottom seed populations to CDOM-rich surface waters of coastal regions, light-inhibition of the small red tide of ~1 ug chl l(-1) of ichthytoxic K. brevis is alleviated. Thence, dead fish serve as a supplementary nutrient source, yielding large, self-shaded red tides of ~10 ug chl l(-1). The source of phosphorus is mainly of fossil origin off west Florida, where past nutrient additions from the eutrophied Lake Okeechobee had minimal impact. In contrast, the P-sources are of mainly anthropogenic origin off Texas, since both the nutrient loadings of Mississippi River and the spatial extent of the downstream red tides have increased over the last 100 years. During the past century and particularly within the last decade, previously cryptic Karenia spp. have caused toxic red tides in similar coastal habitats of other western boundary currents off Japan, China, New Zealand, Australia, and South Africa, downstream of the Gobi, Simpson, Great Western, and Kalahari Deserts, in a global response to both desertification and eutrophication.

Modification of the properties of elongating RNA polymerase by persistent association with nascent antiterminator RNA.

Nascent RNA encoded by putL, a cis-acting antitermination site of bacteriophage HK022, increases readthrough of terminators by directly modifying the transcript elongation complex. To characterize the interaction between the antiterminator RNA and RNA polymerase, we stalled the elongation complex downstream of putL and determined the sensitivity of the transcript to ribonuclease cleavage. Part of PutL RNA was protected from cleavage by wild-type polymerase, but not by a mutant with a defect in put-dependent antitermination. We also exposed the stalled complex to oligonucleotides complementary to putL RNA, restarted transcription, and measured antitermination. Some, but not all, complementary oligonucleotides inhibited antitermination. Finally, cleavage of the RNA between putL and the 3'-end released putL RNA from the stalled complex and prevented antitermination.

Causal attributions and male sexual arousal: the impact of attributions for a bogus erectile difficulty on sexual arousal, cognitions, and affect.

After viewing 2 sexually explicit films, 52 sexually functional participants were given bogus feedback indicating a low erectile response. The men were given either an external, fluctuating attribution (i.e., poor films) or an internal, stable attribution (i.e., problematic thoughts about sex) for the low arousal. As hypothesized, participants in the external, fluctuating group evidenced greater erectile response and subjective arousal during a 3rd film than did participants given the internal, stable attribution. This may indicate that after an occasion of erectile difficulty, the cause to which the difficulty is attributed plays an important role in future sexual functioning.

Constitutive expression of a transcription termination factor by a repressed prophage: promoters for transcribing the phage HK022 nun gene.

Lysogens of phage HK022 are resistant to infection by phage lambda. Lambda resistance is caused by the action of the HK022 Nun protein, which prematurely terminates early lambda transcripts. We report here that transcription of the nun gene initiates at a constitutive prophage promoter, P(Nun), located just upstream of the protein coding sequence. The 5' end of the transcript was determined by primer extension analysis of RNA isolated from HK022 lysogens or RNA made in vitro by transcribing a template containing the promoter with purified Escherichia coli RNA polymerase. Inactivation of P(Nun) by mutation greatly reduced Nun activity and Nun antigen in an HK022 lysogen. However, a low level of residual activity was detected, suggesting that a secondary promoter also contributes to nun expression. We found one possible secondary promoter, P(Nun)', just upstream of P(Nun). Neither promoter is likely to increase the expression of other phage genes in a lysogen because their transcripts should be terminated downstream of nun. We estimate that HK022 lysogens in stationary phase contain several hundred molecules of Nun per cell and that cells in exponential phase probably contain fewer.

Commonality and specificity of personality disorder profiles in subjects with trauma histories.

Recently, attention has been drawn to a range of disturbances in personality functioning that commonly characterize individuals with a history of severe or prolonged trauma. Many of these features overlap with criteria for some of the Axis II personality disorders. The current study investigated the similarity of personality disorder features in different samples of patients with trauma histories, and specificity of such features compared to other psychiatric samples. Profiles of Axis II features, based on relative frequencies of individual disorder "diagnoses" derived from a common measure (Personality Diagnostic Questionnaire-Revised), were compared in three trauma samples: male Vietnam combat veterans with PTSD, female inpatients with a history of childhood sexual abuse, and female outpatients with a history of childhood sexual abuse. The PDQ-R derived profiles in each of the three trauma samples were then compared with similar PDQ-R derived profiles in published reports of psychiatric samples selected for other diagnoses. Each of the three Spearman rank correlations among the three trauma samples were significant, ranging from .72 to .94. There was a clear pattern of higher correlations within the trauma samples (average correlation of .81) than between the trauma and nontrauma samples (average correlations of .11, .36, and .25 between the nontrauma samples and the combat sample, inpatient sexual abuse sample, and outpatient sexual abuse sample, respectively). The findings suggest that a pattern of personality disorder features may be distinctly associated with individuals with trauma histories, at least of the type examined here. Future studies using more clinically valid measures of personality features and including other types of trauma samples are needed to determine the generalizability of the current findings. Also needed are studies with longitudinal designs to address questions of causal pathways that may underlie such associations.

Family values in the age of genomics: comparative analyses of temperate bacteriophage HK022.

HK022 is a temperate coliphage related to phage lambda. Its chromosome has been completely sequenced, and several aspects of its life cycle have been intensively studied. In the overall arrangement, expression, and function of most of its genes, HK022 broadly resembles lambda and other members of the lambda family. Upon closer view, significant differences emerge. The differences reveal alternative strategies used by related phages to cope with similar problems and illuminate previously unknown regulatory and structural motifs. HK022 prophages protect lysogens from superinfection by producing a sequence-specific RNA binding protein that prematurely terminates nascent transcripts of infecting phage. It uses a novel RNA-based mechanism to antiterminate its own early transcription. The HK022 protein shell is strengthened by a complex pattern of covalent subunit interlinking to form a unitary structure that resembles chain-mail armour. Its integrase and repressor proteins are similar to those of lambda, but the differences provide insights into the evolution of biological specificity and the elements needed for construction of a stable genetic switch.

Recognition of core binding sites by bacteriophage integrases.

Bacteriophage integrases promote recombination between DNA molecules that carry attachment sites. They are members of a large and widely distributed family of site-specific recombinases with diverse biological roles. The integrases of phages lambda and HK022 are closely related members of this family, but neither protein efficiently recombines the attachment sites of the other phage. The nucleotides responsible for this specificity difference are located close to the points of recombinational strand exchange, within an integrase binding motif called the extended core binding site. There are four imperfectly repeated copies of this motif in each set of phage attachment sites, but only two, B' and C, contain major specificity determinants. When these specificity determinants were replaced by the corresponding nucleotides from a site with the alternative specificity, the resulting mutant was recombined by both integrases. Thus, the determinants act by impeding recombination promoted by the non-cognate integrase. We found that identical nucleotide substitutions within different core site copies had different effects on recombination, suggesting that integrase does not recognize each of the extended core binding sites in the same way. Finally, substitution at several positions in lambda integrase with the corresponding HK022-specific amino acids prevents recombination of lambda attachment sites, and this defect can be suppressed in an allele-specific manner by appropriate substitutions of HK022-specific nucleotides in the extended core binding sites.

The antiterminator RNA of phage HK022.

The put sites of phage HK022 increase the processivity of transcription and thereby promote the expression of viral genes that are located downstream of transcription terminators. RNA polymerase molecules that have traversed a put site are converted to a terminator-resistant form by the put transcript. We analyzed the structure and function of put transcripts by determining the effects of put mutations on terminator read-through, and by probing wild-type and mutant put RNAs with structure-specific nucleases. The results support the prediction that the secondary structure of the active transcript consists of two hairpin stems that are separated by a single unpaired base. The identity of bases in certain bulges and internal loops is important for activity, while that of most bases in the terminal loops is not. Many bases in the stems can be replaced with little or no effect on activity provided that base-pairing is maintained.

The conceptual relationship between panic disorder and male erectile dysfunction.

Despite evidence of a relationship between sexual dysfunction and panic disorder, there have been few clinical reports addressing the nature of the association between these phenomena. We present three case reports of men diagnosed with panic disorder with agoraphobia, who presented for treatment of erectile problems. In each of the three cases, the similarity between sensations experienced during sexual arousal and those experienced during panic attacks is noted. The purpose of these case presentations is to stimulate further empirical examination of sex-panic states and to alert practitioners of the possible assessment and treatment implications for such individuals. The symptomatic overlap exhibited in these cases is conceptualized from both a psychobiological model of panic disorder and from Barlow's model of sexual dysfunction in an effort to provide a theoretical framework to guide future research and clinical assessment.

Transcripts that increase the processivity and elongation rate of RNA polymerase.

Transcripts encoded by the cis-acting antitermination sites (put sites) of lambdoid phage HK022 promote readthrough of downstream transcription terminators. Proper conformation of the transcripts is essential for activity, since put mutations that prevent the formation of predicted RNA stems prevented antitermination, and suppressor mutations that restore the stems restored antitermination. Antitermination does not appear to require proteins other than RNA polymerase, since put-dependent readthrough of multiple sequential terminators was observed in a purified transcription system consisting of template, polymerase, substrates, and buffer. Transcription of put also increased the elongation rate of polymerase, very likely by suppressing pausing. A mutation that alters the zinc-finger region of the beta' subunit of polymerase specifically prevented the put-dependent increases in terminator readthrough and elongation rate. The simplicity of HK022 antitermination contrasts with that of other known antitermination pathways. We propose that the central effector is a transcript that directly alters the elongation properties of RNA polymerase.

Identifying determinants of recombination specificity: construction and characterization of chimeric bacteriophage integrases.

Bacteriophage integrases are members of a family of structurally related enzymes that promote recombination between DNA molecules that carry specific sites. Phages lambda and HK022 encode closely related integrases that recognize different sets of sequences within the core regions of their respective attachment sites. To locate the amino acid residues that determine this difference in specificity, we isolated recombinant phages that produce chimeric integrases and measured the ability of these chimeras to promote recombination of lambda and HK022 sites in vivo. A chimera that is of lambda origin except for one HK022 residue at position 99 and 12 HK022 residues located between positions 279 and 329 had wild-type HK022 specificity and activity for both integrative and excisive recombination. Chimeras containing certain subsets of these 13 residues had incomplete specificity. The region around position 99 is not well-conserved in other members of the integrase family, but the 279-329 segment includes residues that are highly conserved and believed to be directly involved in catalysis. Many chimeras were inactive in recombining either HK022 or lambda sites. Selection for mutants that restored activity to these chimeras revealed sets of residues that are likely to interact with each other.

Identifying determinants of recombination specificity: construction and characterization of mutant bacteriophage integrases.

The Integrases of bacteriophages lambda and HK022 promote recombination between DNA molecules that carry attachment sites. The two integrases are about 70% identical in sequence and catalyze nearly identical reactions, but recognize different sets of sites. To identify the amino acids that determine this difference in specificity, we selected mutants of lambda integrase with increased ability to recombine HK022 sites. This selection yielded eleven different amino acid substitutions at eight different positions. Three of the positions belong to a larger set that were identified as important for the lambda/HK022 specificity difference by analysis of chimeric integrases. Substitution of the HK022 for the corresponding lambda residue at each of these three positions increased recombination of HK022 sites, and one double substitution, N99D-E319R, increased recombination to nearly wild-type HK022 levels. Mutations at the other five positions changed residues that are identical in the wild-type proteins or are at positions identified by chimera analysis as unimportant for the lambda/HK022 specificity difference. All of the mutants isolated by selection for increased recombination of HK022 sites retained considerable ability to recombine lambda sites. However, we found that substitution of HK022 for lambda residues at three additional positions, S282P, G283K, and R287K, specifically reduced recombination of lambda sites. These three substitutions when combined with N99D and E319R were sufficient to change the specificity of lambda to that of HK022 integrase. The first three substitutions act principally to prevent recombination of lambda sites, and the second two to remove a barrier to recombination of HK022 sites. We suggest that many natural alterations in the specificity of protein-DNA interactions occur by multi-step changes that first relax and then restrict specificity.

A zinc-binding region in the beta' subunit of RNA polymerase is involved in antitermination of early transcription of phage HK022.

Antitermination of early transcription in phage HK022 requires no virus-encoded proteins and thus differs from antitermination by other lambdoid phages. It does require cis-acting phage sequences, which may be analogous to the lambdoid nut sites. To identify host proteins involved in antitermination, we isolated 14 Escherichia coli mutants that are specifically blocked in HK022 growth. The mutations are located in the rpoC gene, which encodes the beta' subunit of RNA polymerase. Each mutation alters one of three amino acid residues located within a cluster of four completely conserved cysteine residues that are believed to bind zinc. We examined the effect of one mutation on HK022 antitermination in vivo. rpoCY75N greatly reduced readthrough of a strong rho-independent transcription terminator placed downstream of the HK022 PL promoter and nutL analog, but did not decrease promoter activity. Purified enzyme had a similar effect on PL-directed transcription in vitro: wild-type but not mutant polymerase read through a strong rho-independent terminator located immediately downstream of the nutL analog with high efficiency. We suggest that interaction of the putative zinc-binding domain of the RNA polymerase beta' subunit with the HK022 antitermination sites suppresses transcription termination, and that this interaction can occur in the absence of other proteins.

Lambda integrase cleaves DNA in cis.

In the Int family of site-specific recombinases, DNA cleavage is accomplished by nucleophilic attack on the activated scissile phosphodiester bond by a specific tyrosine residue. It has been proposed that this tyrosine is contributed by a protomer bound to a site other than the one being cleaved ('trans' cleavage). To test this hypothesis, the difference in DNA binding specificity between closely related integrases (Ints) from phages lambda and HK022 was exploited to direct wild type Ints and cleavage- or activation-defective mutants to particular sites on bispecific substrates. Analysis of Int cleavage at individual sites strongly indicates that DNA cleavage is catalyzed by the Int bound to the cleaved site ('cis' cleavage). This conclusion contrasts with those from previous experiments with two members of the Int family, FLP and lambda Int, that supported the hypothesis of trans cleavage. We suggest explanations for this difference and discuss the implications of the surprising finding that Int-family recombinases appear capable of both cis and trans mechanisms of DNA cleavage.

Growth phase variation of integration host factor level in Escherichia coli.

We have measured the intracellular abundance of integration host factor (IHF), a site-specific, heterodimeric DNA-binding protein, in exponential- and stationary-phase cultures of Escherichia coli K-12. Western immunoblot analysis showed that cultures that had been growing exponentially for several generations contained 0.5 to 1.0 ng of IHF subunits per microgram of total protein and that this increased to 5 to 6 ng/microgram in late-stationary-phase cultures. IHF is about one-third to one-half as abundant in exponentially growing cells as HU, a structurally related protein that binds DNA with little or no site specificity. Wild-type IHF is metabolically stable, but deletion mutations that eliminated one subunit reduced the abundance of the other when cells enter stationary phase. We attribute this reduction to the loss of stabilizing interactions between subunits. A mutation that inactivates IHF function but not subunit interaction increased IHF abundance, consistent with results of previous work showing that IHF synthesis is negatively autoregulated. We estimate that steady-state exponential-phase cultures contain about 8,500 to 17,000 IHF dimers per cell, a surprisingly large number for a site-specific DNA-binding protein with a limited number of specific sites. Nevertheless, small reductions in IHF abundance had significant effects on several IHF-dependent functions, suggesting that the wild-type exponential phase level is not in large excess of the minimum required for occupancy of physiologically important IHF-binding sites.

A segment of the phage HK022 chromosome is a mosaic of other lambdoid chromosomes.

We report the sequence of a region of the PR operon of lambdoid phage HK022 and an analysis of the proteins it encodes. This region has DNA sequence elements and open reading frames that resemble those found in phages lambda, P22, and phi 80. The open reading frames encode homologs of the lambda CII transcription activator, the P22 DNA replication proteins, and a fourth protein of unknown function.