The dynamics of the N/P ratio and stratification in a large nitrogen-limited estuary as a result of upwelling: a tendency for offshore Nodularia blooms

The effect of upwelling on the preconditions for noxious cyanobacterial blooms in a nitrogen-limited estuary is studied with Nodularia blooms in the Gulf of Finland especially in mind. An idealised physical–chemical model is derived and integrated. The physical development in the model agrees with a classical picture of upwelling for the scales of interest. The chemical component indicates a transient minimum of dissolved inorganic nitrogen to phosphorus ratio in the middle of the gulf, coinciding with the stratification maximum resulting from physical dynamics. A general tendency for offshore cyanobacterial blooms in similar physical and biological conditions is deduced from these results.     

Identification of keto acids in arctic bramble,Rubus arcticus L. as methyl esters of their 2,4-dinitrophenylhydrazones

The major keto acids in arctic bramble,Rubus arcticus L. were investigated. The acids were isolated with anionic and cationic ion-exchange resins, converted to 2,4-dinitrophenylhydrazones, and purified with an Al₂O₃ column. The derivatives were separated on a silica gel G thin-layer plate and esterified with methanol-HCl and the methyl esters of the keto acid 2,4-dinitrophenylhydrazones formed were analyzed on an OV-1-glass capillary gas-liquid chromatography column and with mass spectrometry. 2-Oxoglutaric, pyruvic, oxaloacetic, and glyoxylic acids were identified. The mass spectra of the derivatives are presented.     

Relationship between local perfusion and FFA uptake in human skeletal muscle-no effect of increased physical activity and aerobic fitness.

We investigated heredity-independent effects of increased physical activity and aerobic fitness on skeletal muscle free fatty acid (FFA) uptake, perfusion, and their heterogeneity at rest and during exercise. Also, the relationship between local skeletal muscle FFA uptake and perfusion was studied. Nine young adult male monozygotic twin pairs with significant difference in physical activity [229 min (SD 156) average time spent for conditioning exercise per week in more and 98 min (SD 71) in less active twins, P = 0.013] and aerobic fitness [18% (SD 10) difference in maximum O2 uptake] between brothers were studied using positron emission tomography. Submaximal knee-extension exercise increased perfusion, FFA uptake, and oxygen uptake in quadriceps femoris muscles 6-10 times compared with resting values (P < 0.001). More active twins tended to utilize more oxygen, while no differences were found in muscle perfusion or FFA uptake between groups. Mean perfusion and FFA uptake correlated strongly at a whole muscle level, both at rest (r = 0.97, P = 0.03 in more and r = 0.98, P = 0.02 in less active twins) and during exercise (r = 0.99, P = 0.01 and r = 0.94, P = 0.06), but at the voxel level (87 mm3) correlation was only moderate during exercise [r = 0.73 (SD 0.08) vs. r = 0.74 (SD 0.10), P = 0.92] and weak at rest [r = 0.28 (SD 0.13) vs. r = 0.33 (SD 0.21), P = 0.58]. Exercise decreased both perfusion and FFA uptake heterogeneity within the muscles (P < 0.001) similarly in both groups. In conclusion, long-term history of moderately increased physical activity tends to enhance muscle oxidative metabolism, but it does not have any significant influence on the FFA uptake or perfusion rates or their heterogeneity in skeletal muscle. Submaximal knee-extension exercise decreases heterogeneity of muscle FFA uptake and perfusion and improves matching between local muscle perfusion and FFA uptake. Thus it seems that the genetic influence is more important to determine the heterogeneity of perfusion and FFA uptake in skeletal muscle than exercise training.     

Properties of food loads delivered to nestlings in the pied flycatcher: effects of clutch size manipulation, year, and sex

Experimental manipulation of the number of altricial offspring is supposed to modify parental expenditure in birds. In addition to the observed increase in parental feeding rate, it is also possible that the choice of prey or the size of load may change with the changing demand for food. Sexual differences in the provisioning response are also expected, on the basis of earlier studies. We examined the effect of brood size manipulation on choice of prey brought to nestlings and load size in the pied flycatcher. The composition and size of loads differed between years, possibly depending on varying availability of different prey types. Males responded to brood size enlargement by gathering heavier loads, whereas females showed no response. The alteration of load size in males was not explained by a larger number of prey items or mean prey size, but was a combination of these components. It is likely that males also increased their work rate in response to increased food demand at the nest. The absence of response in females might be because they are unable to increase work rate any further, or because food delivery rate in females can not be optimized by changing load properties. Received: 18 December 1997 / Accepted: 1 March 1998     

Modified base compositions at degenerate positions of a mutagenic oligonucleotide enhance randomness in site-saturation mutagenesis.

Site-saturation mutagenesis, using degenerate oligonucleotide primers, is a frequently used method in introducing various mutations in a selected target codon. Oligonucleotides that are synthesized using equimolar concentrations of nucleoside phosphoramidites (dA, dC, dG, dT) in the positions to be saturated, result in a mutant population that is biased towards the original nucleotides. We found that this bias could be eliminated by modifying the concentrations of nucleoside phosphoramidites during the oligonucleotide synthesis. We synthesized eight degenerate oligonucleotides to saturate eight different codons, and sequenced a total of 344 mutagenized codons. In six of these eight oligonucleotides, we reduced to varying extents the concentrations of those nucleotides in the target positions that would form base pairs with the template. From the data, we analyzed the effects of different base compositions in the oligonucleotides when mutagenizing different codons, the influence of the positions of mismatches, and the significance of different non-Watson-Crick base pairs. Based on these results, we suggest levels to which different phosphoramidites should be reduced when synthesizing oligonucleotides for site-saturation mutagenesis.     

Release of Rubella Virus Ribonucleic Acid from Ribonucleoprotein by Polyanions

Rubella virus ribonucleoprotein was accessible to pancreatic ribonuclease, Pronase, and certain polyanions. Most of the ribonucleic acid (RNA) label was made acid-soluble by ribonuclease, whereas Pronase and the polyanions liberated 40S RNA from the ribonucleoprotein.     

Investigations of dye binding in the sequential staining of mucosaccharides by Alcian Yellow-Alcian Blue. 1. Histochemical experiments on different animal and human mucosaccharides

Synopsis It may be assumed that, histochemically, carboxyl groups and sulphate half-ester groups of muco electrolyte concentration of the dye baths in the two steps of a sequential Alcian Yellow-Alcian Blue method. In the present study the specificity and reliability of this method has been investigated.When the staining conditions were the same in both steps, the second dye (Alcian Blue) was found to stain mucosubstances in spite of the prior staining with Alcian Yellow. Binding of Alcian Blue was observed in all but very dilute Alcian Blue solutions. The degree of Alcian Blue binding depended on the dye concentration and staining time of the second step (Alcian Blue), and it varied widely for different mucosubstances. Although an incomplete saturation of anionic groups with dye molecules in the first step cannot be completely excluded, it is thought that Alcian Blue displaces Alcian Yellow from the carboxyl and sulphate groups of mucosubstances in tissue sections.It seems that the sequential Alcian Yellow-Alcian Blue method, under the conditions investigated, does not provide a reliable means for differentiating carboxyl and sulphate groups of mucosbstances in tissue sections simultaneously, because the second dye obviously is capable of displacing the first dye from sulphate groups. However, it is possible to distinguish non-sulphated acid mucosaccharides from sulphated mucosaccharides.     

Comparative proteome cataloging of Lactobacillus rhamnosus strains GG and Lc705

The present study reports an in-depth proteome analysis of two Lactobacillus rhamnosus strains, the well-known probiotic strain GG and the dairy strain Lc705. We used GeLC-MS/MS, in which proteins are separated using 1-DE and identified using nanoLC-MS/MS, to generate high-quality protein catalogs. To maximize the number of identifications, all data sets were searched against the target databases using two search engines, Mascot and Paragon. As a result, over 1600 high-confidence protein identifications, covering nearly 60% of the predicted proteomes, were obtained from each strain. This approach enabled identification of more than 40% of all predicted surfome proteins, including a high number of lipoproteins, integral membrane proteins, peptidoglycan associated proteins, and proteins predicted to be released into the extracellular environment. A comparison of both data sets revealed the expression of more than 90 proteins in GG and 150 in Lc705, which lack evolutionary counterparts in the other strain. Differences were noted in proteins with a likely role in biofilm formation, phage-related functions, reshaping the bacterial cell wall, and immunomodulation. The present study provides the most comprehensive catalog of the Lactobacillus proteins to date and holds great promise for the discovery of novel probiotic effector molecules.     

Infant Growth after Preterm Birth and Mental Health in Young Adulthood

Objectives

Faster growth after preterm birth benefits long-term cognitive functioning. Whether these benefits extend to mental health remains largely unknown. We examined if faster growth in infancy is associated with better self-reported mental health in young adults born preterm at very low birth weight (VLBW) (<1500g).

Study Design

As young adults, participants of the Helsinki Study of Very Low Birth Weight Adults self-reported symptoms of depression and attention deficit/hyperactivity disorder (ADHD) (n = 157) and other psychiatric problems (n = 104). As main predictors of mental health outcomes in linear regression models, we used infant weight, length, and head circumference at birth, term, and 12 months of corrected age, and growth between these time points. Growth data were collected from records and measures at term and at 12 months of corrected age were interpolated. Additionally, we examined the moderating effects of intrauterine growth restriction.

Results

Size at birth, term, or 12 months of corrected age, or growth between these time points were not associated with mental health outcomes (p-values >0.05). Intrauterine growth restriction did not systematically moderate any associations.

Conclusions

Despite the high variability in early growth of VLBW infants, the previously described association between slow growth in infancy and poorer cognitive functioning in later life is not reflected in symptoms of depression, ADHD, and other psychiatric problems. This suggests that the development of cognitive and psychiatric problems may have dissimilar critical periods in VLBW infants.     

Interferon affects the formation of adhesion plaques in human monocyte cultures

When monocytes isolated from human blood adhere to glass substratum, actin- and vinculin-containing punctate plaques rapidly appear at the ventral surface of the cells. We show here that highly purified human leukocyte interferon (IFN) can inhibit formation of these adhesion plaques in a dose-dependent manner. Complete inhibition was obtained when 300 IU/ml IFN were added into the cell-seeding medium. Plaques already formed in the absence of IFN were only partially affected by subsequent addition of IFN into the culture medium. Prevention by IFN of the formation of the adhesion plaques was associated with loosened attachment of the cells to the substratum. Effect of IFN on cellular morphology was complex. At higher doses, IFN added to the cultures within 24 h of seeding almost completely inhibited the differentiation of monocytes to macrophages and most of the cells remained rounded. At lower doses, however, an enhancement of the bipolar spreading was seen and the end result was a culture with predominantly elongated fibroblastoid cells. The latter cells, unlike the fibroblastoid cells in untreated monocyte-macrophage cultures, were completely devoid of the actin plaques, while the reorganization of vimentin-type intermediate filaments took place in a normal manner. These results further support the view that the actin- and vinculin-containing plaques have a role in mediating firm adherence of human monocytes to growth substratum.