Choosing adolescent smokers as friends: the role of parenting and parental smoking.

The present study examined whether parenting and parental smoking can prevent children from selecting smoking friends during adolescence. 254 Adolescents of one Belgian secondary school participated. Self-administered questionnaires were distributed among 2nd-4th graders (mean ages = 14.2-16.2 years) during spring 2006. Follow-up was conducted 12 months later. Data was analyzed conducting longitudinal social network analyses. Results showed adolescents perceiving high parental psychological control had a significant higher tendency to select smoking friends. Perceived behavioral control and perceived parental support did not affect the selection of smoking friends. Furthermore, maternal smoking behavior affected the selection of smoking friends, although no effect of paternal smoking behavior on the selection of smoking friends was found. Adolescent smoking prevention efforts should focus on the influence of parents through their smoking behavior and their psychological control to decrease adolescents' tendency to select smoking friends resulting in fewer opportunities for negative peer influences to occur.

Nitrogen deprivation strongly affects photosystem II but not phycoerythrin level in the divinyl-chlorophyll b-containing cyanobacterium Prochlorococcus marinus.

Effects of nitrogen limitation on Photosystem II (PSII) activities and on phycoerythrin were studied in batch cultures of the marine oxyphotobacterium Prochlorococcus marinus. Dramatic decreases in photochemical quantum yields (F(V)/F(M)), the amplitude of thermoluminescence (TL) B-band, and the rate of Q(A) reoxidation were observed within 12 h of growth in nitrogen-limited conditions. The decline in F(V)/F(M) paralleled changes in the TL B-band amplitude, indicative of losses in PSII activities and formation of non-functional PSII centers. These changes were accompanied by a continuous reduction in D1 protein content. In contrast, nitrogen deprivation did not cause any significant reduction in phycoerythrin content. Our results refute phycoerythrin as a nitrogen storage complex in Prochlorococcus. Regulation of phycoerythrin gene expression in Prochlorococcus is different from that in typical phycobilisome-containing cyanobacteria and eukaryotic algae investigated so far.

Specification of movement amplitudes for the left and right hands: evidence for transient parametric coupling from overlapping-task performance.

Bimanual coordination tasks suggest transient cross-talk between concurrent specification processes for movements of the left and right hand that vanishes as the time for specification increases. In 2 experiments with overlapping and successive unimanual tasks, the hypothesis of transient coupling was examined for a psychological-refractory-period paradigm. Time for specification was manipulated by varying the delay between first and second signal (Experiment 1) and by precuing the first response (Experiment 2). Participants performed rapid reversal movements of same or different amplitudes with the left and right hands. With different amplitudes, reaction times (RTs) of the second responses were longer than with same amplitudes at short delays, and this disappeared at longer delays in Experiment 1. In Experiment 2, precuing also reduced the difference between RTs of second responses in same-amplitude and different-amplitude trials. These findings are consistent with the hypothesis of transient coupling during amplitude specification obtained with bimanual tasks.

Temporal, but not spatial, context modulates a masked prime's effect on temporal order judgment, but not on response latency.

Three experiments investigated a dissociation originally described by Neumann, Esselmann, and Klotz. Stimuli were geometric shapes, preceded by similar shapes that were masked by metacontrast. Each experiment consisted of three parts. In the reaction time (RT) part, participants saw an array of geometric shapes, one of which was marked by bars, and had to respond to the marked shape's position by pressing an appropriate button. A prime (a similar, but smaller stimulus) preceded either the marked or an unmarked stimulus. In the temporal order judgment (TOJ) part, the task was to judge the temporal order of the marked and the unmarked stimulus. In the detection part, detectability of the prime was tested. Although its detectability was zero or close to zero, the prime affected both RT and the apparent onset as measured by TOJ. The effect on RT was significantly larger than the effect on TOJ (Exp. 1). Increasing the spatial context (number of non-target stimuli in the display) did not affect this pattern (Exp. 2). By contrast, reducing the temporal context (range of stimulus onset asynchronies) abolished the prime's effect in the TOJ task, although the prime affected RT under identical conditions. It is concluded that partially different mechanisms mediate the prime's effect in the two tasks and that the effect of stimulus context on TOJ found in the Neumann et al. study was due to temporal, not spatial context.

[Parametric coupling in sequences of bimanual reversal movements with identical and different amplitudes]. / Parametrische Kopplung bei Folgen beidhändiger Umkehrbewegungen mit gleichen und unterschiedlichen Weiten.

In sequences of bimanual movements, the voluntary modulation of the amplitude of the one hand (inducing hand) induces an involuntary modulation of the amplitude of the other hand (dependent hand), the strength of which increases with increasing tempo. By means of a task in which subjects perform sequences of two short and two long reversal movements in alternation with the inducing hand, but constant short or long reversal movements with the dependent hand, we addressed two questions. The first question was concerned with differences in the effects of tempo on the involuntary amplitude modulation of short and long movements; the second question was whether the involuntary amplitude change fades away or is propagated when bimanual movements with certain target amplitudes are repeated. At low tempo the contralateral effect of voluntary amplitude changes on short-amplitude movements was stronger than the effect on long-amplitude movements, but at high tempo this difference was reversed. This result is not consistent with the assumption that contralateral amplitude modulation results from an overflow of efferent commands, which increases with the force of the movement; however, it is consistent with other findings on a transient coupling during amplitude specification (parametric coupling). The involuntary amplitude change was essentially propagated to the next movement in the sequence and did not fade away. This finding suggests that the assimilation of amplitudes that can be observed in bimanual sequences of movements with different, but for each hand constant, amplitudes could result from an effect of transient parametric coupling during the initial specification of amplitudes and need not necessarily be attributed to cross-talk at the level of motor commands or efferent innervation.

Bimanual coupling during the specification of isometric forces.

The present study investigated the generalizability of the hypothesis of transient coupling during the preparation of bimanual movements (Spijkers and Heuer 1995) to the specification of isometric forces. In the first experiment we used the timed response paradigm (TRP) to examine the time course of the specification process. Subjects had to generate bimanual isometric force pulses while preparation time was controlled by the TRP. Target forces were weak (20% of maximal voluntary force, MVF) or strong (40% MVF) and assigned randomly to each hand. The first experiment revealed the predicted pattern of correlations between the peak forces but, because the subjects tended to delay responding when time for preparation was very brief, the time course of the specification process did not fully match expectations. In the second experiment we improved force-trajectory feedback and presented two initial cues that were expected to induce better preparation of the default force (30% MVF). Both changes were successful and the results further corroborate the transient-coupling hypothesis.

Phycoerythrins of the oxyphotobacterium Prochlorococcus marinus are associated to the thylakoid membrane and are encoded by a single large gene cluster.

An intrinsic divinyl-chlorophyll a/b antenna and a particular form of phycobiliprotein, phycoerythrin (PE) III, coexist in the marine oxyphotobacterium Prochlorococcus marinus CCMP 1375. The genomic region including the cpeB/A operon of P. marinus was analysed. It encompasses 10,153 nucleotides that encode three structural phycobiliproteins and at least three (possibly five) different polypeptides analogous to cyanobacterial or red algal proteins involved either in the linkage of subunits or the synthesis and attachment of chromophoric groups. This gene cluster is part of the chromosome and is located within a distance of less than 110 kb from a previously characterized region containing the genes aspA-psbA-aroC. Whereas the Prochlorococcus phycobiliproteins are characterized by distinct deletions and amino acid replacements with regard to analogous proteins from other organisms, the gene arrangement resembles the organization of phycobiliprotein genes in some other cyanobacteria, in particular marine Synechococcus strains. The expression of two of the Prochlorococcus polypeptides as recombinant proteins in Escherichia coli allowed the production of individual homologous antisera to the Prochlorococcus alpha and beta PE subunits. Experiments using these sera show that the Prochlorococcus PEs are specifically associated to the thylakoid membrane and that the protein level does not significantly vary as a function of light irradiance or growth phase.

Light-harvesting antenna function of phycoerythrin in prochlorococcus marinus

Prochlorococcus marinus strain CCMP 1375 is the sole prokaryote to possess phycoerythrin in addition to (divinyl-)chlorophyll a/b binding antenna complexes. Here we demonstrate, employing a spectrofluorimetric assay, that phycoerythrin serves a light-harvesting antenna function (transfers energy to chlorophylls).

Mucopolysaccharidosis type IIIB (Sanfilippo B): identification of 18 novel alpha-N-acetylglucosaminidase gene mutations.

Mucopolysaccharidosis type IIIB (MPS IIIB or Sanfilippo B disease) is an autosomal recessive storage disorder caused by deficiency of the lysosomal enzyme a-N-acetylglucosaminidase. Mutation screening was performed on a group of 22 patients using a combination of SSCP/heteroduplex analysis of amplified genomic fragments and direct sequencing of cDNA fragments. Twenty-one different mutations were identified, 18 of them novel. Together they account for 82% of the disease alleles. The mutation spectrum consists of two small insertions, two small deletions, three nonsense mutations, and 14 different missense mutations, one of them (M1L) affecting the initiation codon. The vast genetic heterogeneity seen in this disorder is reflected by the fact that only three of the mutations were identified in more than one patient.

Homologous nonallelic recombinations between the iduronate-sulfatase gene and pseudogene cause various intragenic deletions and inversions in patients with mucopolysaccharidosis type II.

About 20% of patients with mucopolysaccharidosis type II (MPS II) have gross structural rearrangements involving the iduronate-sulfatase (IDS) gene in Xq27.3-q28. A nearby IDS pseudogene (IDS-2) promotes nonallelic recombination between highly homologous sequences. Here we describe major rearrangements due to gene/pseudogene recombination. In two unrelated patients, partial IDS gene deletions were found joining introns 3 and 7 of the IDS gene together with gene to pseudogene conversion in the area of breakpoints. In a third patient, a junction between intron 3 of IDS-2 and intron 7 of IDS was seen that was due to a deletion and inversion of the 5' part of the gene. Characterisation of breakpoints in six patients with large inversions revealed that all recombinations of this type occurred in the same area of homology between IDS and IDS-2; they were molecularly balanced, and accompanied by gene conversions in most cases. Apart from diagnostic implications, such naturally occurring recombination 'hot spots' may allow some insight into general features of crossover events in mammals.

The time course of cross-talk during the simultaneous specification of bimanual movement amplitudes.

We investigated the time course of the amplitude specification of rapid bimanual reversal movements (lateral displacements on two digitizers). To this end we used the timed-response paradigm in which the response has to be initiated synchronously with an auditory signal. Information about the required amplitudes was presented at various times before the synchronization signal. Consistent with previous results, the progression of amplitude specification was reflected in the dependence of the amplitudes of the reversal movements on the time interval between amplitude information and synchronization signal. Same or different amplitudes for the hands were used to examine cross-talk at the programming level of the two-level model of intermanual interference. The results indicate the existence of cross-talk in particular at short intervals between information about amplitude and movement initiation. This is consistent with the notion that cross-talk between concurrent processes of amplitude specification is transient and vanishes as the time available for motor programming increases.

Identification of 16 sulfamidase gene mutations including the common R74C in patients with mucopolysaccharidosis type IIIA (Sanfilippo A).

Mucopolysaccharidosis type IIIA (MPS IIIA or Sanfilippo A disease) is a storage disorder caused by deficiency of the lysosomal enzyme sulfamidase. Mutation screening, using SSCP/heteroduplex analyses on cDNA and genomic DNA fragments, was performed in a group of 42 European patients. Sixteen of the 17 different gene mutations characterized have not been previously described. The spectrum of gene lesions consists of two 1-bp deletions (1091delC, 1093delG), an 18-bp duplication (421ins18), a splice site mutation (IVS2-2A-->G), and 13 different missense point mutations. As in other lysosomal storage disorders, the phenotypic heterogeneity is associated with a considerable genetic heterogeneity. The missense mutation R74C, which alters an evolutionary conserved amino acid in the active site of the enzyme, was found on 56% of alleles of 16 Polish patients, whereas it was less frequent among German patients (21% of disease alleles). R245H, a previously reported common mutation, represents 35% of disease alleles in German patients, but only 3% in Polish patients. As the combined frequency of the common mutations (R74C and R245H) in German and Polish populations exceeds 55%, screening for these two mutations will assist molecular genetic diagnosis of MPS IIIA and allow heterozygote testing in these populations.

Identification of 31 novel mutations in the N-acetylgalactosamine-6-sulfatase gene reveals excessive allelic heterogeneity among patients with Morquio A syndrome.

Mutation analysis of the N-acetylgalactosamine-6-sulfate sulfatase gene was performed in a group of 35 patients with mucopolysaccharidosis type IVA from 33 families, mainly of European origin. By nonradioactive SSCP screening, 35 different gene mutations were identified, 31 of them novel. Together they account for 88.6% of the disease alleles of the patients investigated. The vast majority of the gene alterations proved to be point mutations, 23 missense, 2 nonsense, and 3 affecting splicing. Six small deletions (1-27 bp) and one insertion were also characterized. In a Polish family, two mildly affected siblings were compound heterozygotes for R94G and R259Q. Their mother was homozygous for the latter point mutation, leading to enzyme deficiency and a borderline disease phenotype.

Evidence for an iduronate-sulfatase pseudogene near the functional Hunter syndrome gene in Xq27.3-q28.

We are currently characterizing mutations of the iduronate-2-sulfatase (IDS) gene in patients with Hunter syndrome (mucopolysaccharidosis type II). Surprisingly, all 17 patients with a mutation in exon III of the IDS gene identified by us were found to carry both the mutant and wild-type sequences in polymerase chain reaction (PCR) products amplified from genomic DNA. Similarly, two unaffected male controls showed a heterozygous pattern for two different point mutations in exon III. Collectively, the data suggest that at least intron 2, exon III, and the 3'-half of exon II of the functional IDS gene are present in the human genome as (part of) a non-expressed IDS gene. Deletion mapping further suggests that the pseudogene is in distal Xq in physical proximity to the functional IDS gene. The high degree of sequence homology observed between the functional IDS gene and pseudogene results in permanent co-amplification in PCR-based screening methods and makes mutation analysis at the genomic DNA level difficult.

Prenatal diagnosis and carrier detection in mucopolysaccharidosis type II by mutation analysis. A 47,XXY male heterozygous for a missense point mutation.

Identification of iduronate-2-sulphatase (IDS) gene mutations in patients with mucopolysaccharidosis type II (MPS II, Hunter syndrome) allows fast and reliable carrier detection and prenatal diagnosis. We describe here three cases of prenatal diagnosis by direct detection of the gene mutation. In addition to two affected male fetuses from two different families, a 47,XXY fetus carrying both the normal and the mutant allele was diagnosed in a third family. The latter pregnancy was carried to term and the child is obviously not affected by MPS II.

Mucopolysaccharidosis type I: identification of 8 novel mutations and determination of the frequency of the two common alpha-L-iduronidase mutations (W402X and Q70X) among European patients.

A group of 46 European patients with mucopolysaccharidosis type I (MPS I) was screened for mutations of the alpha-L-iduronidase gene. The 2 common nonsense mutations, W402X and Q70X, were identified in, respectively, 37% and 35% of mutant alleles. Considerable differences were seen in the frequency of these 2 mutations in patients from North Europe (Norway and Finland) and other European countries (mainly The Netherlands and Germany). In Scandinavia, W402X and Q70X account for 17% and 62% of the MPS I alleles, respectively, while in other European countries W402X is about 2.5 times more frequent (48%) than Q70X (19%). Eight novel mutations are described including 4 missense mutations, 1 nonsense mutation, 1 insertion of 2 base pairs, and 2 deletions of 1 and 12 base pairs.

Iduronate-2-sulfatase gene mutations in 16 patients with mucopolysaccharidosis type II (Hunter syndrome).

Mutations of the iduronate-2-sulfatase gene were identified in 16 patients with mucopolysaccharidosis type II (Hunter syndrome). Together with another 10 cases reported by us earlier it emerges that about 20% of the patients have deletions of the whole gene or other major structural alterations. One, two or three base pair deletions are found in about 23% of the cases while the remaining about 57% carry point mutations predicting amino acid replacement, premature termination of translation, or aberrant splicing. Molecular analysis of mRNA in splice site mutants showed that these latter defects frequently resulted in use of cryptic splice sites in exons or introns. 62% of the small deletions and point mutations have occurred in 3 of the 9 iduronate-2-sulfatase gene exons. Knowledge of the primary genetic defect allows fast and reliable carrier detection and prenatal diagnosis as well as insight into the relationship between genotype and phenotype.

Molecular analysis in patients with mucopolysaccharidosis type II suggests that DXS466 maps within the Hunter gene.

Hunter disease is an X-linked mucopolysaccharidosis caused by deficiency of the lysosomal enzyme iduronate-2-sulfatase (IDS). Using the IDS cDNA and DNA probes corresponding to loci flanking the IDS locus, we performed molecular genetic studies in two patients with Hunter syndrome. An interstitial deletion spanning the middle part of the IDS gene was found in the first patient. The second patient carries a gross gene rearrangement that can be detected after HindIII or EcoRI digestion of genomic DNA, and is similar to that found recently in seven unrelated Hunter patients. Our data suggest that the structural aberration observed is a partial intragenic inversion. As the same altered hybridization pattern is also revealed by the recently described anonymous DNA probe II-10, which recognizes a frequent TaqI restriction fragment length polymorphism at the DXS466 locus, we conclude that DXS466 maps within the IDS gene, probably in an intron.