Osmotically induced response in representatives of halophilic prokaryotes: the bacterium Halomonas elongata and the archaeon Haloferax volcanii.

Haloferax volcanii and Halomonas elongata have been selected as representatives of halophilic Archaea and Bacteria, respectively, to analyze the responses to various osmolarities at the protein synthesis level. We have identified a set of high-salt-related proteins (39, 24, 20, and 15.5 kDa in H. elongata; 70, 68, 48, and 16 kDa in H. volcanii) whose synthesis rates increased with increasing salinities. A different set of proteins (60, 42, 15, and 6 kDa for H. elongata; 63, 44, 34, 18, 17, and 6 kDa for H. volcanii), some unique for low salinities, was induced under low-salt conditions. For both organisms, and especially for the haloarchaeon, adaptation to low-salt conditions involved a stronger and more specific response than adaptation to high-salt conditions, indicating that unique mechanisms may have evolved for low-salinity adaptation. In the case of H. volcanii, proteins with a typical transient response to osmotic shock, induced by both hypo- and hyperosmotic conditions, probably corresponding to described heat shock proteins and showing the characteristics of general stress proteins, have also been identified. Cell recovery after a shift to low salinities was immediate in both organisms. In contrast, adaptation to higher salinities in both cases involved a lag period during which growth and general protein synthesis were halted, although the high-salt-related proteins were induced rapidly. In H. volcanii, this lag period corresponded exactly to the time needed for cells to accumulate adequate intracellular potassium concentrations, while extrusion of potassium after the down-shift was immediate. Thus, reaching osmotic balance must be the main limiting factor for recovery of cell functions after the variation in salinity.

Differentially transcribed regions of Haloferax volcanii genome depending on the medium salinity.

To identify genomic regions involved in osmoregulation in the extremely halophilic archaeon Haloferax volcanii, we used a technique which involves hybridization of cDNAs obtained at different salinities against a cosmid library of the organism. Both low and high salt concentrations trigger differential expression; however, adaptation to low salinities seems to elicit a wider response. The presence of a large domain within the largest of the megaplasmids with a strong response to low salt concentrations is noteworthy.

Long stretches of short tandem repeats are present in the largest replicons of the Archaea Haloferax mediterranei and Haloferax volcanii and could be involved in replicon partitioning.

We report the presence of long stretches of tandem repeats in the genome of the halophilic Archaea Haloferax mediterranei and Haloferax volcanii. A 30 bp sequence with dyad symmetry (including 5 bp inverted repeats) was repeated in tandem, interspersed with 33-39 bp unique sequences. This structure extends for long stretches--1.4 kb at one location in H. mediterranei chromosome and about 3 kb in the H. volcanii chromosome. The tandem repeats (designated TREPs) show a similar distribution in both organisms, appearing once or twice in the H. volcanii and H. mediterranei chromosomes, and once in the largest, probably essential megaplasmid of each organism but not in the smaller replicons. Sequencing of the structures in both H. volcanii replicons revealed an extremely high sequence conservation in both replicons within the species, as well as in the different organisms. Homologous sequences have also been found in other more distantly related halophilic members of the Archaea. Transformation of H. volcanii with a recombinant plasmid containing a 1.1 kb fragment of the TREPs produced significant alterations in the host cells, particularly in terms of cell viability. The introduction of extra copies of TREPs within the vector significantly alters the distribution of the genome among the daughter cells, as observed by DAPI staining. Although the precise biological role cannot be completely ascertained, all the data conform with the tandem repeats being involved in replicon partitioning in halobacteria.

Effects of salt and temperature on plasmid topology in the halophilic archaeon Haloferax volcanii.

We report here the effect of environmental parameters, salinity, temperature, and an intercalating drug on plasmid topology in the halophilic archaeon Haloferax volcanii. We first studied the topological state of the plasmid pHV11 in media of different salt compositions and concentrations. The superhelical density of plasmid PHV11 varies in a way that depends on the kind of salt and on the concentrations of individual salts. With respect to growth temperature, the plasmid linking number increased at higher temperature in a linear way, contrary to what has been reported for Escherichia coli, in which the plasmid linking number decreased at higher temperature. These results suggest that some of the mechanisms that control DNA supercoiling in halophilic Archaea may be different from those described for E. coli. However, homeostatic control of DNA supercoiling seems to occur in haloarchaea, as in Bacteria, since we found that relaxation of DNA by chloroquine triggers an increase in negative supercoiling.

[Intrauterine growth in full-term twins without risk factors]. / Crecimiento intrauterino en gemelos de término sin factores de riesgo.

Twins are analysed according to the intrauterine growth curve constructed for single fetus. The relationship of twins with length, weight, head circumference and the weight length-index is studied. Twins over 36 weeks gestation age, without maternal or fetal pathologies were selected. It is concluded the twins pregnancy "per se" constitutes on its own, a risk factor regarding the intrauterine growth curve, particularly in relation with the weight curve.

Transcription at different salinities of Haloferax mediterranei sequences adjacent to partially modified PstI sites.

Two genomic sequences from the halophilic archaeon Haloferax mediterranei, where we had found PstI restriction-pattern modifications depending on the salinity of the growth medium, have been studied. A markedly salt-dependent differential expression has been detected in the nearby regions. Two of the open reading frames characterized correspond to two of the differentially expressed transcripts. In both cases the PstI sites were included in purine-pyrimidine alternancies suggestive of Z-DNA structures and located in non-coding regions with frequent repetitive motifs. A long alternating adenine-thymine tract also appears in the upstream regions of one of these open reading frames. A possible role of local DNA configuration in osmoregulation in this organism is discussed.

Evidence for salt-associated restriction pattern modifications in the archaeobacterium Haloferax mediterranei.

DNA restriction pattern modifications were detected when Haloferax mediterranei was grown in low (10%) salt concentrations. After cells were grown again in optimal (25%) salt concentrations, the original pattern was recovered. These salt-associated DNA modifications were revealed with 5% of the 160 DNA fragments cloned and used as probes in hybridization experiments. Patterns obtained when genomic DNA was digested with different restriction enzymes showed that these modifications are related not to insertions or deletions in genome but to modifications of some specific sequences.

Caracterización clínica de un grupo de hijos de madre hipertensa / Clinical characterization of hipertensive mothers of a children group

El síndrome hipertensivo del embarazo se describe en la literatura como un problema prevalente en la mujer joven y primigesta, de etiología no precisada y causante de morbimortalidad materna y fetal. Los datos de los recién nacidos hijos de madre hipertensa (RN-HMH) fueron registrados prospectivamente en fichas codificadas. Se compararon a los datos de recién nacidos de madres no hipertensas, también prospectivos. De dos mil catorce HMH tuvieron retardo de crecimiento intrauterino (RCIU) 16%, EG < 37 semanas 12%, PN < 2.500 g 13%, PN < 1.500 g 0,3%, hospitalización neonatal 10,4% (Z ratio test p < 0,01). Ciento treinta y seis HMH hospitalizados tuvieron una distribución no diferente de enfermedades que 906 hijos de madres no hipertensas hospitalizados. La poliglobulia fue significativamente más frecuente en los HMH 16% vs 6,3% (Z ratio test p < 0,05). No así los problemas respiratorios, cardiovasculares, neurológicos, enterocolitis necrosante, trombocitopenia y otros. Se concluye que el HMH tiene alto riesgo de hospitalización por prematuridad y RCIU y la poliglobulia se destaca como morbilidad propia del grupo

Influencia de la talla materna sobre el crecimiento fetal / Influence of the maternal stature on the intrauterine growth

Un estudio prospectivo de crecimiento fetal se ha realizado en los últimos 10 años. Damos cuenta en este trabajo de la influencia de la talla materna y de la curva de Crecimiento Intrauterino (CIU) obtenida. Métodos: Enrolamiento de Recién Nacidos (RN) vivos, seleccionados sin factores de retardo de crecimiento intrauterino. Técnicas antropométricas controladas. Resultados: 10.615 madres presentan una talla 158 cm ñ 5,7 cm ( x ñ DE). Fueron divididas en 3 grupos: 2.128 con talla > 163 cm, 6.549 con talla 153-162 y 1.938 con talla < 152. Los 3 grupos tuvieron recién nacidos con peso, talla circunferencia craneana y edad gestacional significativamente relacionados en forma directa a la talla materna. Test de hipótesis para promedios: p < 0,01. El índice ponderal no fue influido por la talla materna. Novecientos cuarenta y cuatro madres de talla baja tuvieron recién nacidos adecuados a la edad gestacional, que se compararon a 944 RN AEG con peso de nacimiento pareado y cuyas madres tenían talla normal. Los recién nacidos de las madres bajas tuvieron mayor riesgo de Apgar < 7 al min. y de meconio en líquido amniótico, riesgo atribuible a las condiciones obstétricas. Conclusiones : La talla materna influye significativamente sobre el peso, talla y circunferencia craneana de nacimiento. No hubo diferencia de morbilidad neonatal a un mismo peso de nacimiento. Por lo tanto, es apropiado tomar en cuenta la talla materna en la clasificación del recién nacido. Los pesos de nacimiento obtenidos en este estudio son similares a los comunicados por otros autores chilenos. Estos recién nacidos se consideran representativos del recién nacido chileno y la Sociedad Chilena de Pediatría ha aprobado el uso de esta curva a nivel nacional

Linfangiectasia pulmonar congénita / Congenital pulmonary lymphangiectasis

Presentamos el caso de un recién nacido con linfangiectasia pulmonar congénita no asociada a otras malformaciones congénitas, que falleció dentro de las primeras 24 horas de vida, destacando los aspectos clínicos, radiológicos y anatomopatológicos

[Congenital pulmonary lymphangiectasis]. / Linfangiectasia pulmonar congénita.

Congenital pulmonary lymphangiectasis is a rare cause of severe respiratory distress in the newborn period and most of these patients die, usually within the first 24 hours of life. It may present as an isolated anomaly or it may be associated with other congenital abnormalities, most commonly cardiac in origin, as is the case of total obstruction of the pulmonary venous drainage. Congenital pulmonary lymphangiectasis may be also associated with lymphatic anomalies of other portions of the body or with other non-lymphatic, non-cardiac congenital malformations. Chest radiographs show more commonly that the lungs are hyperexpanded and present a diffuse interstitial reticulonodular pattern. The differential diagnosis from the radiological standpoint should include total anomalous pulmonary venous drainage and pneumonia. We present the case of a newborn infant with congenital pulmonary lymphangiectasis who died within the first 24 hours of life, emphasizing clinical, radiological and pathological findings.

Crecimiento intrauterino en recién nacidos chilenos de clase media / Intrauterine growth in chilean middle class newborn infants

Se presentan los datos de 11.543 recién nacidos vivos en 10 años (1978-1987) en Hospital Clínico de la Universidad Católica, seleccionados prospectivamente sin factores de riesgo de retardo de crecimiento intrauterino. La selección de los casos fue importante para obtener percentiles adecuados de peso vs. edad gestacional. Estos son diferentes a los de Lubchenco (publicación previa) y este patrón se recomienda para perfeccionar el diagnóstico postnatal de retardo de crecimiento intrauterino en los recién nacidos chilenos

Crecimiento intrauterino según sexo fetal y paridad materna / Intrauterine growth according to fetal sex and maternal parity

Se presentan los datos de 8.533 recién nacidos vivos entre 1978 y 1985 en Hospital Clínico U. Católica, distribuidos en 3.291 hijos de primigestas, 4.594 de multíparas, 648 multigestas primíparas fueron excluidas, 4.199 femeninos y 4.334 masculinos, todos seleccionados prospectivamente sin factores de riesgo de retardo de crecimiento intrauterino. Los varones tuvieron pesos de nacimiento promedio 180-228 g mayores que las niñas y los hijos de multíparas superaron en 85-140 g a los de primigestas. Estas diferencias resultaron significativas en las edades gestacionales de término y se recomienda considerarlas en estudios epidemiológicos. Se comunican los pesos de nacimiento en promedios y percentiles, considerando paridad y sexo y un gráfico para corrección del promedio según sexo y paridad

[Intrauterine growth according to fetal sex and maternal parity]. / Crecimiento intrauterino según sexo fetal y paridad materna.

Influence of fetal sex on intrauterine growth (by birth weight) was studied in 8,533 newborn infants (4,199 females and 4,334 males) without known risk factors. Similar effects of maternal parity were also evaluated in infants of the same cohorts (648 infants from multigestae women were excluded because of antecedent abortion, 3,291 were first born to primigravidae and 4,594 were born to multiparae mothers). Male infants mean birth weights were 180-228 g greater than those of female infants. Male infants weighed 3,340 g +/- 390 (mean +/- SD) and 3,643 g +/- 414 (mean +/- SD) and female babies: 3,210 g +/- 376 and 3,502 g +/- 393 (mean +/- SD) at 38 and 41 weeks of gestational age respectively. Mean birth weights of newborn from multiparae were 85-140 g higher than those from primigravidae. Babies from multiparae weighed 3,337 g +/- 393 (mean +/- SD) and 3,608 g +/- 418 (mean +/- SD) and babies from primigravidae: 3,202 g +/- 372 mean +/- SD) and 3,523 g +/- 384 (mean +/- SD) at 38 and 41 weeks of gestational age in each case. All of these data were statistically different at 38 throughout 41 weeks of gestational age. A correction is suggested for birth weight according to a graph of differences between general mean birth weight and those for multiparae, primigravidae, males and females.

[Intrauterine growth in Chilean middle class newborn infants]. / Crecimiento intrauterino en recién nacidos chilenos de clase media.

Intrauterine growth of 11,543 newborn infants, liveborn between 1978 to 1987 that met prospective selection conditions (without intrauterine growth retardation risk) and their data are reported. MBW and weight percentiles 10, 25, 50, 75, 90 from 26 throughout 42 week of gestational age are reported. Selection of cases was important in obtaining adequate percentiles of birth-weight vs gestational age. The intrauterine growth pattern herein reported is recommended for evaluation of chilean newborns, because it is different to that of some foreign countries and the studied sample seems representative of chilean babies.