External and Internal Microbiomes of Antarctic Nematodes are Distinct, but More Similar to each other than the Surrounding Environment.

Host-associated microbiomes have primarily been examined in the context of their internal microbial communities, but many animal species also contain microorganisms on external host surfaces that are important to host physiology. For nematodes, single strains of bacteria are known to adhere to the cuticle (e.g., Pasteuria penetrans), but the structure of a full external microbial community is uncertain. In prior research, we showed that internal gut microbiomes of nematodes (Plectus murrayi, Eudorylaimus antarcticus) and tardigrades from Antarctica's McMurdo Dry Valleys were distinct from the surrounding environment and primarily driven by host identity. Building on this work, we extracted an additional set of individuals containing intact external microbiomes and amplified them for 16S and 18S rRNA metabarcoding. Our results showed that external bacterial microbiomes were more diverse than internal microbiomes, but less diverse than the surrounding environment. Host-specific bacterial compositional patterns were observed, and external microbiomes were most similar to their respective internal microbiomes. However, external microbiomes were more influenced by the environment than the internal microbiomes were. Non-host eukaryotic communities were similar in diversity to internal eukaryotic communities, but exhibited more stochastic patterns of assembly compared to bacterial communities, suggesting the lack of a structured external eukaryotic microbiome. Altogether, we provide evidence that nematode and tardigrade cuticles are inhabited by robust bacterial communities that are substantially influenced by the host, albeit less so than internal microbiomes are.

Life at extreme elevations on Atacama volcanoes: the closest thing to Mars on Earth?

Here we describe recent breakthroughs in our understanding of microbial life in dry volcanic tephra ("soil") that covers much of the surface area of the highest elevation volcanoes on Earth. Dry tephra above 6000 m.a.s.l. is perhaps the best Earth analog for the surface of Mars because these "soils" are acidic, extremely oligotrophic, exposed to a thin atmosphere, high UV fluxes, and extreme temperature fluctuations across the freezing point. The simple microbial communities found in these extreme sites have among the lowest alpha diversity of any known earthly ecosystem and contain bacteria and eukaryotes that are uniquely adapted to these extreme conditions. The most abundant eukaryotic organism across the highest elevation sites is a Naganishia species that is metabolically versatile, can withstand high levels of UV radiation and can grow at sub-zero temperatures, and during extreme diurnal freeze-thaw cycles (e.g. - 10 to + 30 °C). The most abundant bacterial phylotype at the highest dry sites sampled (6330 m.a.s.l. on Volcán Llullaillaco) belongs to the enigmatic B12-WMSP1 clade which is related to the Ktedonobacter/Thermosporothrix clade that includes versatile organisms with the largest known bacterial genomes. Close relatives of B12-WMSP1 are also found in fumarolic soils on Volcán Socompa and in oligotrophic, fumarolic caves on Mt. Erebus in Antarctica. In contrast to the extremely low diversity of dry tephra, fumaroles found at over 6000 m.a.s.l. on Volcán Socompa support very diverse microbial communities with alpha diversity levels rivalling those of low elevation temperate soils. Overall, the high-elevation biome of the Atacama region provides perhaps the best "natural experiment" in which to study microbial life in both its most extreme setting (dry tephra) and in one of its least extreme settings (fumarolic soils).

The pH dependence of tryptophan fluorescence of goat alpha-lactalbumin with particular reference to the effect of binding of an impurity from milk.

Two processes giving rise to changes in tryptophan fluorescence of goat alpha-lactalbumin below pH 7 have been studied. Both of these spectral transitions are strongly influenced by the presence of an impurity which binds to the protein if its contact at acid pH with the milk mother liquor is prolonged during its preparation. Transition II, the U leads to N conversion, follows the same course at both 2 and 25 degrees C, i.e. a minimum of three abnormally titrating groups are normalized during the conformational change at both temperatures. The difference in this conclusion from that made earlier (Kronman, M.J., Jeroszko, J. and Sage, G.W. (1972) Biochim. Biophys. Acta 285, 145-166) that groups are normalized at 25 and at 2 degrees C was found to be due to binding of the impurity to the protein used in the earlier study. Transition I, which we detect between pH 7 and 4.4 and which appears to be due to perturbation of tryptophans by vicinal ionizing groups, overlaps Transition II, the U leads to N conversion. However, the fluorescence above approx. 340 nm in the emission spectrum appears to be free of contributions from the former process and can be used in a valid analysis of the thermodynamics of the latter process.

Comparative fluorescence properties of bovine, goat, human and guinea pig alpha lactalbumin. Characterization of the environments of individual tryptophan residues in partially folded conformers.

alpha Lactalbumin exists as a partially folded conformer (U form) at acid pH. A second partially folded conformer (H form) is formed above 60 degrees. Comparison of the changes in tryptophan fluorescence which occur on forming U and H for the bovine, goat, human and guinea pig proteins, as well as analysis of fluorescence properties for the bovine protein and an N bromo succinimide derivative of this protein, have made it possible to determine which tryptophan residues give rise to such changes in fluorescence, and to draw a distinction between the molecular structure of the U and H forms of the protein. Trp 28 and 109 in the native state transfer their excitation energy to trp 63 whose fluorescence is quenched by a pair of vicinal disulfide bridges. This process persists in the U form of the protein, but is absent in the H conformer. Most of the change in fluorescence seen in the N in equilibrium with U conversion is due to increase in yield of trp 28, while the changes in fluorescence occurring on formation of the H form are due to exposure of trp 63 and elimination of its quenching and/or excited state transfer from 28 to 109.

What physicians should know about consumer satisfaction.

Physicians must recognize the contemporary role consumers play in the delivery process. Although it is common knowledge that without consumers there would be little need for the elaborate health systems in existence today, few physicians actively plan for, implement and systematically evaluate services delivered. The rising cost of malpractice insurance in this age of spiraling materials and equipment expense, is forcing more physicians to consider better ways of serving and keeping their patients. This article describes one approach, consumer satisfaction.

Writing for publication: a workshop to prepare faculty as medical writers.

BACKGROUND AND OBJECTIVES: A 2 1/2-day Writing for Publication Workshop was presented to faculty and fellows for 5 successive years, 1991-1995. This paper describes the workshop curriculum and reports evaluation results. METHODS: A three-part evaluation plan incorporated both quantitative and qualitative methods. First, a nine-item questionnaire was administered to the 1992-1995 participants immediately prior to and after the workshop to identify perceived change in knowledge and skills. Second, a follow-up qualitative interview was administered to the 1991 and 1992 participants to identify their perceptions of the workshop's usefulness. Third, pre- and postworkshop publications of the 1991 and 1992 participants were analyzed to identify types of publications and significant differences in rates of publication. RESULTS: Eighty individuals participated in the five workshops given during the 1991-1995 period. Pre/post self-assessment data indicated significant increases in perceived knowledge and skill in all nine areas of assessment. The follow-up interview data showed that participants felt that the workshop motivated them to begin and sustain writing projects, gave them skills that made their writing more effective, and demystified the submission and publication processes. Analysis of the difference between pre- and postworkshop rates of publication showed a significant increase in the rate of publication. CONCLUSIONS: The evaluation findings indicate that the Writing for Publication Workshop met its educational objectives. Future curricula to prepare faculty as medical writers need to be tested using quasi-experimental designs to determine their impact on publication productivity and quality.

Medical care for special children.

Comprehensive health care planning can augment the educational programming for children with exceptional health and/or learning needs. The coordination of medical service and education is critically needed to reduce the traditional gulf between these two essential disciplines. Bridging this gulf will enable patients and their families, referral sources, and providers to collectively profit from the effort.

The value of birth control.

PIP: The attempt was made to obtain an improved estimate of the economic value of birth control programs in developing countries. A medium sized econometric simulation model -- based on data covering a cross-section of 67 countries -- was constructed to investigate the implications to a developing economy of birth prevention. Fertility measures were included in the model as important endogenous variables in the economic process, and parameter values were supplied by formal estimation rather than expert judgment. A matrix of age-specific birth and survival rates was used. The model has sufficient detail to generate a complete age distribution for the population, yielding improved estimates of the value of birth control and other growth policies. Initial focus is on the construction of the model. This is followed by simulation of the system with simulated paths compared to observed paths for a few countries. Projections of real per capita output and other variables with and without the presence of a birth control program are presented. The size of the differential economic effect associated with lower fertility is examined for 17 sets of initial conditions corresponding to a selection of 17 developing countries. Comparisons of birth control with other forms of investment are made.^ieng