Linkage mapping in tetraploid willows: segregation of molecular markers and estimation of linkage phases support an allotetraploid structure for Salix alba x Salix fragilis interspecific hybrids

Salix alba-Salix fragilis complex includes closely related dioecious polyploid species, which are obligate outcrossers. Natural populations of these willows and their hybrids are represented by a mixture of highly heterozygous genotypes sharing a common gene pool. Since nothing is known about their genomic constitution, tetraploidy (2n=4x=76) in willow species makes basic and applied genetic studies difficult. We have used a two-way pseudotestcross strategy and single-dose markers (SDMs) to construct the first linkage maps for both pistillate and staminate willows. A total of 242 amplified fragment length polymorphisms (AFLPs) and 50 selective amplifications of microsatellite polymorphic loci (SAMPL) markers, which showed 1:1 segregation in the F(1) mapping populations, were used in linkage analysis. In S. alba, 73 maternal and 48 paternal SDMs were mapped to 19 and 16 linkage groups covering 708 and 339 cM, respectively. In S. fragilis, 13 maternal and 33 paternal SDMs were mapped in six and 14 linkage groups covering 98 and 321 cM, respectively. For most cosegregation groups, a comparable number of markers linked in coupling and repulsion was identified. This finding suggests that most of chromosomes pair preferentially as occurs in allotetraploid species exhibiting disomic inheritance. The detection of 10 pairs of marker alleles from single parents showing codominant inheritance strengthens this hypothesis. The fact that, of the 1122 marker loci identified in the two male and female parents, the vast majority (77.5%) were polymorphic and as few as 22.5% were shared between parental species highlight that S. alba and S. fragilis genotypes are differentiated. The highly difference between S. alba- and S. fragilis-specific markers found in both parental combinations (on average, 65.3 vs 34.7%, respectively) supports the (phylogenetic) hypothesis that S. fragilis is derived from S. alba-like progenitors.

[Pica and iron-deficiency anemia in a 2-year old Indian child]

Pica is the compulsive ingestion of nonnutritive substances. The causes are not known, but the symptom is often associated either with iron-deficiency or with pregnancy. The authors report on a case of pica in a 2-year old Indian child, affected by a serious ferropenic anaemia.

Analysis of gene expression during flowering in apomeiotic mutants of Medicago spp.: cloning of ESTs and candidate genes for 2n eggs

Mutants showing features of apomixis have been documented in alfalfa (Medicago sativa L.), a natural outcrossing sexual species. A differential display of mRNAs that combines cDNA-AFLP markers and bulked segregant analysis was carried out with the aim of selecting expressed sequence tags (ESTs) and cloning candidate genes for apomeiosis in mutants of alfalfa characterized by 2n egg formation at high frequencies. The approach enabled us to select either mutant- or wild type-specific transcript derived-fragments and to detect transcriptional changes potentially related to 2n eggs. Sequence alignments of a subset of 40 polymorphic clones showed significant homologies to genes of known function. An EST with identity to a β-tubulin gene, highly expressed in the wild type and poorly expressed in the apomeiotic mutants, and an EST with identity to a Mob1-like gene, qualitatively polymorphic between pre- and post-meiotic stages, were selected as candidate genes for apomeiosis because of their putative roles in the cell cycle. A number of clone-specific primers were designed for performing both 5' and 3' rapid amplification of cDNA ends to obtain the full-length clones. Southern blot hybridization revealed that both clones belong to a multi-gene family with a minimum of three genomic DNA members each. Northern blot hybridization of total RNA samples and in situ hybridization of whole buds enabled the definition of their temporal and spatial expression patterns in reproductive organs. Experimental achievements towards the elucidation of apomeiotic megasporogenesis in alfalfa are presented and discussed.

[Experience in the treatment of neonatal respiratory distress with nasal CPAP]

Since the early 1970s, when continuous positive airways pressure (CPAP) was introduced as a method of treatment of neonatal respiratory distress, many technical approaches have been suggested. The Authors report their experience with a new technique for nasal CPAP which has been developed to minimize impedance to breathing and offering maximum airway pressure stability and tolerance to leakage. Thirty-two newborns with symptoms of RDS were treated with Infant Flow System, a new device for nasal CPAP with nasal prongs which resulted inexpensive, simple to use and with lower risk for serious complications. Furthermore, the results suggest that treatment by early CPAP with nasal prongs in newborns presenting symptoms of RDS can be effective in reducing the number of newborns transferred to the third level Unit.

Non-furosemide-related renal calcifications in premature infants with bronchopulmonary dysplasia

Renal calcification is a known complication of long-term furosemide therapy in infants with bronchopulmonary dysplasia (BPD). In a prospective study the clinical course and long-term renal sequelae of renal calcifications of 19 consecutive premature neonates (birthweight < 1250 g) with bronchopulmonary dysplasia who did not receive furosemide were examined. Infants were divided into two different groups on the basis of ultrasound evidence of renal calcifications (RC group) or absence of renal calcifications (NRC group). Serial examinations, performed at the age of 1, 2, 3, 6, 9 and 12 months, showed that 12 infants at the mean age of 68.5 +/- 12.8 days of life had renal calcifications (63%), and 3 of them had nephrolithiasis; 8 had bilateral renal calcifications. Among the 9 survivors, 2 had chronic renal calcifications at the age of 9 months; however, all normalized at the age of 12 months. Twelve infants received hydrochlorothiazide and spironolactone (63%), 17 had prolonged courses of xanthines and dexamethasone (89.5%), while furosemide was not part of the routine pharmacological administration. Statistical analysis showed that birthweight, gestational age, Apgar score and length of parenteral nutrition were comparable in the RC and NRC group infants. Mean serum creatinine, creatinine clearance, fractional sodium excretion and urinary calcium excretion values during the 12-month study period were comparable in the RC and NRC groups. Mechanical ventilation and hospital stay length were instead associated with renal calcification occurrence. The strongest indicator of renal calcification risk for this high-risk population is the severity of the unresolved acute lung disease, where different facets of respiratory management, other than the addition of furosemide, represent sufficient stimuli and renal injury to potentiate stone formation.

[Clinical aspects and diagnosis of neonatal infections caused by group B beta-hemolytic Streptococcus]

Early-onset infection findings caused by Group B Streptococcus occur within 24 hours of birth (60 per cent of cases) but they may appear anytime during the first 5 days of life. In our experience early-onset infection affects both preterm and term neonates. The Authors report the usual clinical signs described for bacterial infections. Unusual findings are also reported: among 34 infants with early-onset infection, the congenital diaphragmatic hernia was associated with GBS septicemia in two neonates; beads of perspiration were the first only clinical finding in one neonate too. Two cases of late-onset infection are also reported.

Methylxanthines increase renal calcium excretion in preterm infants

To determine the effect of a short course of methylxanthines on renal function and on urinary calcium excretion, 20 premature neonates affected by apnea or moderate respiratory distress syndrome were randomly assigned to either a theophylline treatment or to a caffeine treatment group. The protocol included a 24-hour pretreatment study period (I) and a subsequent 24-hour period (II) following 5 days of theophylline (loading dose 5 mg/kg i.v., maintenance dose 2.5 mg/kg/12 h) or caffeine (loading dose 10 mg/kg i.v., maintenance dose 2.5 mg/kg/12 h) administration. Pre- and postxanthine treatment serum sodium, potassium, calcium and phosphorus remained stable, while serum creatinine decreased significantly (p < 0.05). Furthermore, from period I to period II, sodium urine excretion, fractional Na excretion and creatinine clearance remained statistically comparable in both study groups, along with a significant increase (p < 0.05) in calciuria, urinary Ca/creatinine and urinary Ca/Na. Predose caffeine and theophylline serum levels, assessed on the 5th day of treatment, were 12.8 +/- 1.8 and 7.9 +/- 1.7 micrograms/ml, respectively. Compared to control healthy untreated prematures, the studied premature infants showed a statistically significant increase in urine calcium excretion (10- to 15-fold), which was more evident in the theophylline group. Our data suggest further investigation to determine the long-term renal effects of methylxanthines in premature neonates, to improve assessment of the risk of nephrocalcinosis and osteopenia, in particular in association with various diuretic therapies.