Insights into the Fundamental Physiology of the Uncultured Fe-Oxidizing Bacterium Leptothrix ochracea.

Leptothrix ochracea is known for producing large volumes of iron oxyhydroxide sheaths that alter wetland biogeochemistry. For over a century, these delicate structures have fascinated microbiologists and geoscientists. Because L. ochracea still resists long-term in vitro culture, the debate regarding its metabolic classification dates back to 1885. We developed a novel culturing technique for L. ochracea using in situ natural waters and coupled this with single-cell genomics and nanoscale secondary-ion mass spectrophotometry (nanoSIMS) to probe L. ochracea's physiology. In microslide cultures L. ochracea doubled every 5.7 h and had an absolute growth requirement for ferrous iron, the genomic capacity for iron oxidation, and a branched electron transport chain with cytochromes putatively involved in lithotrophic iron oxidation. Additionally, its genome encoded several electron transport chain proteins, including a molybdopterin alternative complex III (ACIII), a cytochrome bd oxidase reductase, and several terminal oxidase genes. L. ochracea contained two key autotrophic proteins in the Calvin-Benson-Bassham cycle, a form II ribulose bisphosphate carboxylase, and a phosphoribulose kinase. L. ochracea also assimilated bicarbonate, although calculations suggest that bicarbonate assimilation is a small fraction of its total carbon assimilation. Finally, L. ochracea's fundamental physiology is a hybrid of those of the chemolithotrophic Gallionella-type iron-oxidizing bacteria and the sheathed, heterotrophic filamentous metal-oxidizing bacteria of the Leptothrix-Sphaerotilus genera. This allows L. ochracea to inhabit a unique niche within the neutrophilic iron seeps.IMPORTANCELeptothrix ochracea was one of three groups of organisms that Sergei Winogradsky used in the 1880s to develop his hypothesis on chemolithotrophy. L. ochracea continues to resist cultivation and appears to have an absolute requirement for organic-rich waters, suggesting that its true physiology remains unknown. Further, L. ochracea is an ecological engineer; a few L. ochracea cells can generate prodigious volumes of iron oxyhydroxides, changing the ecosystem's geochemistry and ecology. Therefore, to determine L. ochracea's basic physiology, we employed new single-cell techniques to demonstrate that L. ochracea oxidizes iron to generate energy and, despite having predicted genes for autotrophic growth, assimilates a fraction of the total CO2 that autotrophs do. Although not a true chemolithoautotroph, L. ochracea's physiological strategy allows it to be flexible and to extensively colonize iron-rich wetlands.

Cell-specific nitrogen- and carbon-fixation of cyanobacteria in a temperate marine system (Baltic Sea).

We analysed N2 - and carbon (C) fixation in individual cells of Baltic Sea cyanobacteria by combining stable isotope incubations with secondary ion mass spectrometry (SIMS). Specific growth rates based on N2 - and C-fixation were higher for cells of Dolichospermum spp. than for Aphanizomenon sp. and Nodularia spumigena. The cyanobacterial biomass, however, was dominated by Aphanizomenon sp., which contributed most to total N2 -fixation in surface waters of the Northern Baltic Proper. N2 -fixation by Pseudanabaena sp. and colonial picocyanobacteria was not detectable. N2 -fixation by Aphanizomenon sp., Dolichospermum spp. and N. spumigena populations summed up to total N2 -fixation, thus these genera appeared as sole diazotrophs within the Baltic Sea's euphotic zone, while their mean contribution to total C-fixation was 21%. Intriguingly, cell-specific N2 -fixation was eightfold higher at a coastal station compared to an offshore station, revealing coastal zones as habitats with substantial N2 -fixation. At the coastal station, the cell-specific C- to N2 -fixation ratio was below the cellular C:N ratio, i.e. N2 was assimilated in excess to C-fixation, whereas the C- to N2 -fixation ratio exceeded the C:N ratio in offshore sampled diazotrophs. Our findings highlight SIMS as a powerful tool not only for qualitative but also for quantitative N2 -fixation assays in aquatic environments.

Suicide epidemics and newspaper reporting.

This paper looks at the relationship between suicide-related newspaper reports and a subway-suicide epidemic. More reports were published during the epidemic, without statistically significant differences between epidemic and nonepidemic years. There did not appear to be an excess of reports antecedent to the suicide. The role of newspapers is discussed with particular reference to suicide epidemics. The need for studies of content of newspaper items related to self-harm is emphasized.

A psychiatric clinic for the deaf.

From the increasing number of requests being received by the Deafness Clinic (as many in the first three months of 1981 as in the whole of 1980), it would appear there is a sizable minority in Canada for whom psychiatric and mental health services are not easily accessible in their present form. Not only does hearing impairment significantly affect language, communication and social skills acquisition, it also separates persons so affected from services that other Canadians take for granted.

Involuntary admission to hospital and treatment in Ontario: is pessimism among physicians warranted?

In 1978 the Ontario Mental Health Act was revised to contain more specific and objective criteria for involuntary admission to hospital and treatment. The new requirements have elicited critical and pessimistic comments from psychiatrists and other physicians in Ontario. Two recent cases, described in this paper, indicate that the changes in the law have not obstructed good clinical care and treatment and may, in fact, be salutary to the management of patients who are involuntarily admitted to hospital.

Schizophrenia: group support for relatives.

This paper outlines the organization and evolution of educational-support groups for the families and friends of schizophrenic patients. The organization involved three phases of expanding services to this target population. Our findings are that: a) relatives experience stage-specific reactions to the fact of schizophrenia in the family; b) topic areas for discussion tend to be the same in different groups; c) as total attendance grows (larger groups), individual attendance rate drops; d) the groups tend to evolve into self-led committees; e) the maximum benefit from the groups, as reported by the participants, is the opportunity to share common, painful experiences. Future goals lie in the encouragement of relative-run community organizations for schizophrenia and the clarification of the role of families in the development and course of the illness.

An aftercare program for problem patients.

The high readmission rates of discharged psychiatric patients have forced mental health professionals to play closer attention to aftercare planning. A program was developed at a psychiatric hospital in Ontario in 1977 to deal with "problem patients"--those who were deemed difficult to place in the community by the referral person or department. The program was characterized by shared institutional-community staffing, systematic aftercare assessment and planning, a crisis intervention approach to discharge, the use of a transitional staff member with patients, and the development of close relationships with community agencies. Study data show that the program was effective in limiting the number of readmissions during its first two years to 20 per cent.

Planning for psychiatric emergencies.

Hospital emergency services have been used increasingly in recent years. This has resulted in questions as to the true nature of patients' complaints and the appropriateness of this type of care. Since the increase in the number of psychiatric emergency patients has paralleled that for patients at other types of emergency clinics a study was conducted at the Clarke Institute of Psychiatry, Toronto, to examine the situation prior to the inception in 1977 of a crisis intervention unit. It was found that most patients had both psychiatric and social difficulties, and it was considered that planning should concentrate on strategies for efficient management of the clinical problems.