1.1-billion-year-old porphyrins establish a marine ecosystem dominated by bacterial primary producers.

The average cell size of marine phytoplankton is critical for the flow of energy and nutrients from the base of the food web to higher trophic levels. Thus, the evolutionary succession of primary producers through Earth's history is important for our understanding of the radiation of modern protists ∼800 million years ago and the emergence of eumetazoan animals ∼200 million years later. Currently, it is difficult to establish connections between primary production and the proliferation of large and complex organisms because the mid-Proterozoic (∼1,800-800 million years ago) rock record is nearly devoid of recognizable phytoplankton fossils. We report the discovery of intact porphyrins, the molecular fossils of chlorophylls, from 1,100-million-year-old marine black shales of the Taoudeni Basin (Mauritania), 600 million years older than previous findings. The porphyrin nitrogen isotopes (δ15Npor = 5.6-10.2‰) are heavier than in younger sedimentary sequences, and the isotopic offset between sedimentary bulk nitrogen and porphyrins (εpor = -5.1 to -0.5‰) points to cyanobacteria as dominant primary producers. Based on fossil carotenoids, anoxygenic green (Chlorobiacea) and purple sulfur bacteria (Chromatiaceae) also contributed to photosynthate. The low εpor values, in combination with a lack of diagnostic eukaryotic steranes in the time interval of 1,600-1,000 million years ago, demonstrate that algae played an insignificant role in mid-Proterozoic oceans. The paucity of algae and the small cell size of bacterial phytoplankton may have curtailed the flow of energy to higher trophic levels, potentially contributing to a diminished evolutionary pace toward complex eukaryotic ecosystems and large and active organisms.

Dual-diagnosis empirical and developmental-humanistic approaches.

The association between alcohol and/or drug dependence and major psychiatric conditions such as schizophrenia has received increased attention from the professional community. Terms such as "dual diagnosis" used to designate these clinical occurrences have become common, reflecting the interest mentioned. This chapter reviews the prevalence of the association between substance abuse and psychiatric disorder, the nature of the interactions observed, and some of the implications for patient care and health policy. Following this empirical perspective, we present a developmental-humanistic approach that has been used in the psychotherapeutic management of these problems. Our review of information on dual diagnosis suggests that the association between the two processes--substance abuse and psychiatric disorder--is not fortuitous or just the result of environmental conditions. There are complex physiopathological links at the neurobiological level that deserve research attention.

Care-givers' support group: one hospice's approach.

The Care-givers' Support Group has been a successful intervention in helping hospice family members work through the numerous emotional tasks with which they are faced in the dying process and in bereavement. This paper focuses on the significance of a support group setting as illustrated through case studies of hospice families.

Clinical assessment of affective behaviors.

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