Language impairment in Swedish bilingual children: a comparison between bilingual and monolingual children in Malmö.

UNLABELLED: In this study two groups of children were compared, 192 bilingual and 246 monolingual, referred over a 12-mo period to University Hospital in Malmö for suspected language impairment. Compared with monolingual children, bilingual children ran a significantly lower risk (RR = 0.76, p < 0.0001) of being referred by a child health centre, and a significantly higher risk (RR= 1.54, p < 0.0103) of being referred after 5 y of age. In the bilingual group there was also a significantly higher risk of parental refusal of assessment (RR = 2.35, p < 0.0016) and of the children being diagnosed with a severe language impairment (RR = 1.87, p < 0.0009). The risk for bilingual children with severe language impairment being discharged owing to non-attendance was high (RR = 6.20, p < 0.0002) compared to monolingual children. The risk increased with severity of language impairment. CONCLUSION: Bilingual children displayed a higher risk of a diagnosis of severe language impairment and of being discharged for non-attendance. The problem of low compliance among bilingual parents, despite strong indications of parental distress, must be addressed.

Heat stress response in pea involves interaction of mitochondrial nucleoside diphosphate kinase with a novel 86-kilodalton protein.

In this work we have further characterized the first mitochondrial nucleoside diphosphate kinase (mtNDPK) isolated from plants. The mitochondrial isoform was found to be especially abundant in reproductive and young tissues. Expression of the pea (Pisum sativum L. cv Oregon sugarpod) mtNDPK was not affected by different stress conditions. However, the pea mtNDPK was found to interact with a novel 86-kD protein, which is de novo synthesized in pea leaves upon exposure to heat. Thus, we have evidence for the involvement of mtNDPK in mitochondrial heat response in pea in vivo. Studies on oligomerization revealed that mtNDPK was found in complexes of various sizes, corresponding to the sizes of e.g. hexamers, tetramers, and dimers, indicating flexibility in oligomerization. This flexibility, also found for other NDPK isoforms, has been correlated with the ability of this enzyme to interact with other proteins. We believe that the mtNDPK is involved in heat stress response in pea, possibly as a modulator of the 86-kD protein.

Comprehension and production of relative clauses: a comparison between Swedish impaired and unimpaired children.

The aim of the present study is to investigate the relationship between language comprehension and language production in Swedish children. This was done longitudinally with 10 children with specific language impairment (SLI), aged 4;0 to 6;3 at Time I, and 10 children with unimpaired language development, aged 3;1 to 3;7 at Time I. The target structure was subordination, more precisely relative clauses. The children's comprehension was tested with picture pointing, act-out and oral response tests. Their production was tested with elicited imitation and sentence completion tests. Data were collected twice, with an interval of six months. The results from the unimpaired children at Time I showed a difference between comprehension and production. At Time II these children scored higher on production than on comprehension. The children with SLI scored significantly higher on comprehension than on production at Time I. In half of the SLI group there was a clear development between the two data collection sessions, diminishing the dissociation. On neither testing did the children with SLI differ significantly from the unimpaired children in comprehension. At both testings, however, the children with SLI had significantly more responses where they did not insert the complementizer in relative clauses. The results indicate that the relationship between comprehension and production is different at different stages in development. They also show that structures involving dependency relations are particularly difficult to produce for children with SLI.

Cloning and characterisation of a pea mitochondrial NDPK.

Here we report the cloning of a cDNA encoding the first nucleoside diphosphate kinase (NDPK) isolated from plant mitochondria. Amplification of a 317 nt product was performed by PCR, using oligonucleotide primers based on partial amino acid sequences of the pea mitochondria NDPK and other NDPK isoforms. By screening of a pea cDNA library with this PCR product, a full length clone was obtained. Northern analysis revealed the presence of a 1.1 kb single transcript, with high expression in young leaves and reproductive tissues. The clone encodes a precursor protein of 232 amino acids (26 kDa), including an N-terminal extension of 80 amino acids (9 kDa). Analysis of the deduced amino acid sequence confirmed its identity with the sequences obtained from the purified mature pea mitochondrial NDPK. In vitro import experiments carried out in isolated pea mitochondria showed targeting and processing of the 27 kDa precursor into a 16.5 kDa mature form. Phylogenetic analysis of some vertebrate and plant isoforms of NDPK showed that the pea mtNDPK groups together with the NDPK3 isoform from A. thaliana and the chloroplastic NDPK III from spinach. We suggest that it is possible to design a novel classification of the different NDPK isoforms according to their subcellular localisation and origin.

Purification of a serine and histidine phosphorylated mitochondrial nucleoside diphosphate kinase from Pisum sativum.

For the first time, to our knowledge, a nucleoside diphosphate kinase (NDPK) has been purified from plant mitochondria (Pisum sativum L.). In intact pea leaf mitochondria, a 17.4-kDa soluble protein was phosphorylated in the presence of EDTA when [gamma-32P]ATP was used as the phosphate donor. Cell fractionation demonstrated that the 17.4-kDa protein is a true mitochondrial protein, and the lack of accessibility to EDTA of the matrix compartment in intact mitochondria suggested it may have an intermembrane space localization. The 17.4-kDa protein was purified from mitochondrial soluble proteins using ATP-agarose and anion exchange chromatography. Amino-acid sequencing of two peptides, resulting from a trypsin digestion, revealed high similarity with the conserved catalytic phosphohistidine site and with the C-terminal of NDPKs. Acid and alkali treatments of [32P]-labelled pea mitochondrial NDPK indicated the presence of acid-stable as well as alkali-stable phosphogroups. Thin-layer chromatography experiments revealed serine as the acid-stable phosphogroup. The alkali-stable labelling probably reflects phosphorylation of the conserved catalytic histidine residue. In phosphorylation experiments, the purified pea mitochondrial NDPK was labelled more heavily on serine than histidine residues. Furthermore, kinetic studies showed a faster phosphorylation rate for serine compared to histidine. Both ATP and GTP could be used as phosphate donor for histidine as well as serine labelling of the pea mitochondrial NDPK.

A protein tyrosine kinase of chloroplast thylakoid membranes phosphorylates light harvesting complex II proteins.

Phosphorylation of chloroplast thylakoid proteins, in particular light harvesting complex II (LHC II), is believed to play an important role in regulating photosynthetic electron transfer. Evidence supporting the involvement of multiple protein kinases in this system is mounting. We have re-examined pea thylakoid membranes and found evidence for a membrane-associated protein tyrosine kinase (PTK). Phosphorylation of many thylakoid proteins, including LHC II, is sensitive to treatment with the tyrosine kinase inhibitor genistein. Anti-phosphotyrosine antibodies react specifically with nine thylakoid proteins, two of which have been identified as components of LHC II. The phosphate associated with these two proteins is also resistant to strong base and acid treatment, further substantiating the assignment of phosphotyrosine. Potential interactions between this novel chloroplast PTK activity and the well-documented threonine kinase activities are discussed and the presence of a cascade of thylakoid protein kinases is proposed.

Protein synthesis by isolated pea mitochondria is dependent on the activity of respiratory complex II.

In isolated pea (Pisum sativum L.) mitochondria incorporation of 35S-methionine into newly synthesised proteins was influenced by the presence of site-specific inhibitors of the respiratory electron-transport chain. These effects were not produced by changes in the rate of respiratory electron transport itself nor by changes in ATP concentration. Protein synthesis was inhibited by inhibitors of ubiquinone reduction but not by inhibitors of ubiquinol oxidation. By the use of additional inhibitors at specific sites of the respiratory chain, different oxidation-reduction states were obtained for the different complexes in the electron-transport chain. It was found that electron transport through succinate:ubiquinone oxidoreductase (respiratory complex II) was specifically required for protein synthesis, even when all the other conditions for protein synthesis were satisfied. We suggest that a subunit of complex II, or a component closely associated with complex II, is involved in a regulatory system that couples electron transport to protein synthesis.

The acquisition of Swedish as second language in a group of Arabic-speaking pre-school children: word order patterns and phrasal morphology.

Children with Swedish as a second language (L2) and Swedish children with specific language impairment (SLI) have displayed interesting similarities in their linguistic development. A group of 18 normally developed Arabic-speaking children, five and six years old, were tested with respect to their development of word order patterns and phrasal morphology in the noun phrase. The results were in accordance with Pienemann's processability theory, that predicts the order of acquisition of both morphological and syntactical structures. The results on word order patterns showed similarities between L2 and SLI children. Processability theory could be a powerful tool in analyzing the grammar in children with SLI.

Histidine and tyrosine phosphorylation in pea mitochondria: evidence for protein phosphorylation in respiratory redox signalling.

A 37 kDa protein in pea mitochondria was found to contain phosphorylated residues. Phosphorylation was acid-labile but stable in alkali solution, a unique property of phosphorylation on histidine, indicating that a signal transduction pathway with homology to bacterial two-component systems might exist in plant mitochondria. We also describe the first example of tyrosine phosphorylation in plant organelles and the first indication of protein phosphorylation as part of a redox signalling mechanism in mitochondria. Labelling of three proteins (28, 27 and 12 kDa) was found to be dependent on the redox state of the reaction medium. Their phospho-groups were resistant to alkali as well as acid treatment and labelling was inhibited by the tyrosine kinase inhibitor genistein.

Photosynthesis. Regulation by redox signalling.

Photosynthesis is light-driven redox chemistry. Molecular redox signalling, the coupling of gene expression to electron transfer, is now implicated in the adaptation of photosynthesis to variation in light quality and quantity.

A chimeric and truncated mitochondrial atpA gene is transcribed in alloplasmic cytoplasmic male-sterile tobacco with Nicotiana bigelovii mitochondria.

Protoplast fusions were performed between two sexually produced alloplasmic male-sterile tobacco cultivars, with cytoplasms from Nicotiana bigelovii [Nta (big)S] and N. undulata[Nta(und)S], both of which exhibit homeotic-like phenotypes affecting the petal and stamen whorls. Among the fusion products obtained, both novel male-sterile and pollen-producing cybrid plants were identified. Of the pollen-producing cybrid plants, all of which were indehiscent, some had flowers with stamens that appeared normal when compared to male-fertile tobacco plants. Other hybrid plants were incompletely restored as they exhibited petaloid structures on the anther-bearing pollen-producing stamens. In this study, gel-blot analyses with mitochondrial geneprobes were conducted comparing the mitochondrial DNA of cybrids and male-sterile parents. It was found that the flower morphology typical of the Nta(big)S parental plants, as well as of the novel male-sterile cybrids, coincided with the presence of a chimeric atpA gene copy where an open reading frame of unknown origin was found to be linked in-frame to the 3'-end of a truncated atpA gene. RNA gel-blot hybridizations revealed the presence of atpA transcripts in the malesterile parent Nta(big)S and novel male-sterile cybrids, but which were absent in cybrids capable of pollen production.

Redox conditions specify the proteins synthesised by isolated chloroplasts and mitochondria.

In chloroplasts and mitochondria isolated from pea leaves, (35)S-methionine incorporation reveals that different subsets of proteins are selected for synthesis in the presence of the external redox reagents ferricyanide, ascorbate, duroquinol, dithiothreitol and dithionite, and in the presence of different electron transport inhibitors in the light (in chloroplasts) or with respiratory substrates (in mitochondria). Redox state of specific electron carriers may therefore regulate expression of specific genes in chloroplasts and mitochondria. The results are consistent with the hypothesis that chloroplast and mitochondrial genomes encode proteins whose synthesis must be regulated by electron transport in photosynthesis and respiration.

Extensive nuclear influence on mitochondrial transcription and genome structure in male-fertile and male-sterile alloplasmic Nicotiana materials.

Nuclear influences on mitochondrial transcription and genome organization were analysed in six different male-fertile and male-sterile alloplasmic Nicotiana cultivars. The alloplasmic materials were compared with the corresponding nuclear species (N. tabacum) and cytoplasmic donor species (N. debneyi, N. rapanda or N. suaveolens) in Northern and Southern analyses using twelve different mitochondrial genes as probes. The investigation revealed that the nucleus exerts extensive influence on the expression and structure of the mitochondrial genome. For the majority of the probes, changes in both mitochondrial transcription and DNA patterns in alloplasmic cultivars were detected. Even though changes in transcription patterns, which correlated with male sterility, were detected for three of the probes (atpA, orf25 and coxII), the changes were not consistent for all the male-sterile materials. Likewise, no consistent association between mtDNA restriction patterns and cytoplasmic male sterility (CMS) was detected.

Respiration in Cells and Mitochondria of Male-Fertile and Male-Fertile and Male-Sterile Nicotiana spp.

Three cytoplasmic male-sterile Nicotiana cultivars together with corresponding male-fertile progenitors and restored lines were investigated in order to find possible correlations between respiratory characteristics and male sterility. Oxygen consumption measurements were performed on cells from suspension cultures as well as on mitochondria isolated from green leaves. Inhibitors, which have been reported to specifically block either the cytochrome (KCN) or the alternative (propyl gallate and sali-cylhydroxamic acid [SHAM] respiratory pathways, were used in order to measure the capacity and activity of the two pathways. One of the inhibitors, SHAM, was found unsuitable to measure the activity of the alternative pathway due to the lack of specificity of SHAM for this pathway. A great difference in the capacity of the alternative pathway was detected between the two types of cell materials tested. Mitochondria isolated from green leaves showed a capacity of the alternative pathway of 5 to 20% of total mitochondrial repiration, while the capacity of cells from suspension cultures generally ranged from 50 to 80%. In addition to this, in organello synthesis of mitochondrial proteins revealed differences between mitochondria isolated from green leaves and from cell suspensions. No correlation, however, could be found between respiratory characteristics and male sterility.

Variant mitochondrial protein and DNA patterns associated with cytoplasmic male-sterile lines of Nicotiana.

Variation in mitochondrial protein synthesis and genome organization was investigated. Three different alloplasmic cytoplasmic male-sterile Nicotiana tabacum cultivars, carrying N. repanda, N. suaveolens or N. debneyi cytoplasm, were analysed together with corresponding male-fertile parental and restored material. Although several differences were detected in the proteins synthesized by isolated mitochondria from the male-sterile and male-fertile plants, most of these were related to the origin of the mitochondria. However, a 23 kD protein was synthesized in the male-sterile cultivar carrying N. debneyi mitochondria, but not in other lines containing this cytoplasm. This protein was also present in the male-fertile parent containing N. tabacum mitochondria. Only the enhanced production of a 30 kD protein in the lines carrying mitochondria from N. repanda or N. debneyi was exclusively correlated with CMS. This protein was not present in any of the corresponding male-fertile parental and restored lines. Restriction enzyme analysis of mitochondrial DNA revealed a difference in abundance of a 5.6 kb XhoI fragment between lines containing N. debneyi mitochondria. No rearrangements of mitochondrial DNA was found between male-fertile and male-sterile lines carrying N. repanda or N. suaveolens cytoplasm. These results might indicate that CMS in alloplasmic Nicotiana cultivars is caused by alterations in the expression of mitochondrial genes, rather than by induced changes in the genome.

The Phenotype of a Virescent Chloroplast Mutation in Tobacco Is Associated with the Absence of a 37.5 kD Thylakoid Polypeptide.

The Vir-c mutation is a virescent chloroplast mutation found in a line of plants derived from protoplast fusions between a Nicotina tabacum line and a line containing N. tabacum nuclei with Nicotiana suaveolens cytoplasm. Vir-c displays a lag period in chlorophyll accumulation and granal stack formation in young leaves. We examined total chloroplast protein in young leaves and showed the mutant contains 1.3 to 2.1 times less stromal protein, and 2.9 to 4.3 times less thylakoid protein when compared to the N. tabacum var "Turkish Samsun" control. Electrophoretic patterns of total thylakoid proteins indicated three polypeptides were specifically decreased in amount within the context of the overall reduction in thylakoid protein. Electrophoresis of thylakoid proteins synthesized by chloroplasts isolated from half-expanded leaves demonstrated that mutant chloroplasts did not synthesize a 37.5 kilodalton polypeptide which was synthesized by "Samsun" chloroplasts. A polypeptide of this molecular weight was synthesized by Vir-c chloroplasts isolated from mature leaves which had recovered the normal phenotype. Restriction digestion and electrophoresis of the mutant's chloroplast DNA produced a pattern of restriction fragments different from either N. tabacum or N. suaveolens chloroplast DNA.

Hematological findings in the Norrbottnian type of Gaucher disease.

A controlled study of hematological changes was performed on 14 patients with the Norrbottnian type of Gaucher disease, seven of whom had been splenectomized at least one year before the study. Each patient had two controls matched to age, sex and habitation. Before splenectomy the patients had slight to moderate microcytic, hypochromic anemia which changed after splenectomy to macrocytic, hypochromic anemia. The splenectomized patients had a high percentage of target cells (mean frequency 33%) and a significantly increased hypo-osmotic resistance of the erythrocytes which showed a positive correlation with the number of target cells. Before removal of the spleen the patients had slight leukopenia with a relative increase of mononuclear cells and moderate thrombocytopenia. In the splenectomized patients the thrombocyte count was normal and there was moderate leukocytosis with a persistent relative increase of lymphocytes.