Insulin-like growth factor I enhances the formation of type I collagen in hydrocortisone-treated human osteoblasts

We have studied the effect of insulin-like growth factor I (IGF-I) on the formation of osteocalcin and type I collagen in isolated human osteoblasts. IGF-I at and above 0.1 nM stimulated the formation of type I collagen as measured by the type I procollagen carboxyterminal peptide (PICP), in human osteoblasts, incubated for 72 hrs in serumfree conditions. The secretion of osteocalcin was not affected by IGF-I while 1,25(OH)₂ vitamin D₃ significantly enhanced the formation of osteocalcin. When human osteoblast-like cells were incubated with hydrocortisone (1 M), a significant decrease in the release of both PICP and osteocalcin was seen. Addition of IGF-I to human osteoblasts also treated with hydrocortisone normalized the PICP-formation but did not affect the suppressed osteocalcin-formation. These data indicate that IGF-I reverses selective effects of hydrocortisone on bone.     

Latitudinal clines in life-history variables of anadromous brown trout in Europe

Based on published data, we reviewed clinal variations in life-history characteristics of anadromous brown trout Salmo trutta from 102 European rivers at latitudes between 54 and 70° N. Growth rate in fresh water, mean smolt age, mean sea age at first sexual maturity, proportion of repeal spawners among adults, longevity, and length of adult life span exhibited latitudinal clines. Brown trout grew faster in fresh water, smolted and matured younger, lived fewer years but spawned more times in the south than in the north. The life-history traits studied were often correlated. Longevity, smolt age and sea age at maturity were negatively and smolt length and proportion of repeat spawners among adults were positively correlated with growth rate in fresh water. Longevity was positively correlated with smolt age and sea age at maturity. The latter also increased with increasing smolt age. None of these significant correlations among life history variables, except for those between smolt age and parr growth and proportion of repeat spawners and parr growth, are latitudinal effects. We do not know to what extent the latitudinal variation in life–history traits reflects phenotypic plasticity and to what extent it is caused by inherited differences among populations.     

Migratory behaviour and growth of hatchery-reared post-smolt Atlantic salmon Salmo salar

Individually lagged, 1+ and 2+ hatchery-reared smolts of Atlantic salmon were released in spring and early summer at the mouth of the R. Imsa, south-western Norway. The post-smolts moved mainly northwards in the sea with the coastal current. The estimated mean migratory speed (± s.d. ) of those captured in the sea along the Norwegian coast was 7.45 (± 6.26) km day ⁻¹; in the fjords it was 1.63 (± 2.33) km day⁻². Many of the post-smohs ascended rivers the same year as released; 37.3% of the total number recaptured were caught in R. Imsa, upstream from the site of release, and 5.8% were caught in other rivers throughout middle and southern parts of Norway. The fish recaptured in rivers was probably sexually mature and entered rivers to spawn. Mean specific growth rate for post-smolts caught in the sea was higher than for those caught in R. Imsa (P <0.001) but not for those caught in other rivers (P> 0.05). Post-smolts ascending R. Imsa were smaller at release than those ascending other rivers. However, there was no size difference at release between post-smolts captured in the sea and those recaptured in rivers other than the R. Imsa.     

Is there a threshold size regulating seaward migration of brown trout and Atlantic salmon?

We investigated the influence of variation in body size and growth rate on age of smolting in Atlantic salmon and brown trout in four different Norwegian rivers. In Atlantic salmon smolt ages varied between 2 and 6 years, and in brown trout between 2 and 7 years. Smolt age was negatively correlated with parr growth, and positively correlated with smolt size. Age at smolting was more variable in the two northern than the two southern rivers. Smolt sizes and ages were also more variable in brown trout than in Atlantic salmon. Based on the observed variation in smolt size and age, we reject the hypothesis that a threshold size alone regulates age at smolting. Within populations smolt age depends on growth rate so that fast-growing parr smolted younger and smaller than slow-growing parr. We hypothesize that smolt size and age is a trade-off between expected benefits and costs imposed by differences in individual growth rate.     

Influence of substrate structure on disintegration activity of Moloney murine leukemia virus integrase.

The disintegration activity of Moloney murine leukemia virus (M-MuLV) integrase (IN) was investigated through structural and sequence modifications of a Y substrate that resembles an integration intermediate. The Y substrates, constructed from individual oligonucleotides, contain a single viral long terminal repeat (LTR) joined to a nicked target DNA. Truncation of the double-stranded LTR sequences distal to the conserved 5'-CA-3' dinucleotide progressively diminished disintegration activity. M-MuLV IN was also able to catalyze disintegration of a heterologous double-stranded LTR sequence. Significantly, the activity of M-MuLV IN on single-stranded LTR Y substrates was more dependent on the sequence and length of the LTR strand than that reported for human immunodeficiency virus type 1 (HIV-1) IN. Modifications introduced at the Y-substrate junction demonstrated that the 3'-hydroxyl group at the terminus of the target strand was necessary for efficient joining of the target DNA strands. The presence of a 2'-hydroxyl group at the 3' end of the target strand, as well as a single-nucleotide gap at the LTR-target junction, reduced disintegration activity. The absence of hydroxyl groups on the terminal nucleotide abolished joining of the target strands. The results presented here suggest that M-MuLV IN disintegration activity is dependent on substantially different LTR sequence requirements than those reported for HIV-1 IN and may be mediated primarily through a structural recognition event.     

Partial migration: niche shift versus sexual maturation in fishes

Summary Many fish populations have both resident and migratory individuals. Migrants usually grow larger and have higher reproductive potential but lower survival than resident conspecifics. The decision about migration versus residence probably depends on the individual growth rate, or a physiological process like metabolic rate which is correlated with growth rate. Fish usually mature as their somatic growth levels off, where energetic costs of maintenance approach energetic intake. After maturation, growth also stagnates because of resource allocation to reproduction. Instead of maturation, however, fish may move to an alternative feeding habitat and their fitness may thereby be increased. When doing so, maturity is usually delayed, either to the new asymptotic length, or sooner, if that gives higher expected fitness. Females often dominate among migrants and males among residents. The reason is probably that females maximize their fitness by growing larger, because their reproductive success generally increases exponentially with body size. Males, on the other hand, may maximize fitness by alternative life histories, e.g. fighting versus sneaking, as in many salmonid species where small residents are the sneakers and large migrants the fighters. Partial migration appears to be partly developmental, depending on environmental conditions, and partly genetic, inherited as a quantitative trait influenced by a number of genes.     

ASCOPHYLLUM NODOSUM (PHAEOPHYTA) IN AXENIC CULTURE AND ITS RESPONSE TO THE ENDOPHYTIC FUNGUS MYCOSPHAERELLA ASCOPHYLLI AND EPIPHYTIC BACTERIA1

Ascophyllum nodosum (L.) Le Jol. was freed from bacteria and the endophytic fungus Mycosphaerella ascophylli Cotton by repeated treatment with chlorine solutions and grown in artificial seawater. Two types of axenic culture of different origin were obtained. Type 1 was developed from apices of A. nodosum collected in the sea. Type 2 was from plants which developed from adventitious embryos on rhizoids formed by type 1. This is the first time A. nodosum has been cultivated axenically. Growth of the axenic alga was increased by IAA, 21P and zeatin. Without external growth regulators some strains of the axenic alga deteriorated within a year; others developed a filamentous habit. Sulfur in a reduced state also stimulated growth. Addition of either glucose, mannose or mannitol to the medium caused the formation of calluslike layers of loosely packed colorless cells under the epidermis of the thalli and the epidermis was sloughed off. No increase in thallus length was noticed. Mycosphaerella ascophylli in axenic culture did not excude any substances stimulating growth of the alga, but that does not exclude an influence of the fungus on the alga in vivo. The fungus, when growing within the alga, seemed to have little influence on algal morphology. A bacterized but fungus-free A. nodosum was cultivated in an artificial seawater for 8 years. In the bacteria-free alga, the fungus protruded from the epidermis and evidently utilized the alga as a carbon source. The bacteria thus seem much more important than the fungus for normal growth of the Ascophyllum plant.     

Identification of five hemoglobins in B6C3F1 mice by mass spectrometry and sequence analysis

The aim of the work is to identify and characterize the hemoglobins found in B6C3F1 mice using mass spectrometry. The primary structures are compared to those reported for BALB/c mice. Individual hemoglobin chains were isolated by reversed-phase high performance liquid chromatography (RP-HPLC). The molecular masses of the globins were determined using electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI). The purified globin chains were enzymatically cleaved and the resulting peptides were separated by RP-HPLC. The chains were identified by N-terminal sequencing and mass spectrometry (MALDI). Selected peptides were analysed by Edman degradation. ESI analysis indicates that B6C3F1 mice have two -globin chains (-1 and -2) and at least three β-globin chains, β-1, β-2 and β-3. This is one additional - and one additional β-globin chain than reported in the literature for BALB/c mice. Mass and sequence analysis of enzymatically generated peptides showed variations in the amino acid sequence in the -1, -2, β-2 and β-3 chains compared to the BALB/c mouse hemoglobins (, β^minor and β^major). The study showed that mass spectrometry in combination with traditional protein chemistry is able to identify and locate minor protein sequence variations.     

Neglected aspects of false positive findings of mammography in breast cancer screening: analysis of false positive cases from the Stockholm trial.

OBJECTIVES: To examine the implications of false positive results of mammography in terms of the time lag from screening and complete mammography to the point when women with false positive results are declared free of cancer; the extra examinations, biopsies, and check ups required; and the cost of these extra procedures. DESIGN: Review of women with false positive results from the Stockholm mammography screening trial. SETTING: Department of Oncology, South Hospital, Stockholm. SUBJECTS: 352 and 150 women with false positive results of mammography from the first and second screening rounds of the Stockholm trial. MAIN OUTCOME MEASURES: Extra examinations and investigations required and the cost of these procedures. RESULTS: The 352 women from the first screening round made 1112 visits to the physician and had 397 fine needle aspiration biopsies, 187 mammograms, and 90 surgical biopsies before being declared free of cancer. After six months 64% of the women (219/342) were declared cancer free. The 150 women in the second round made 427 visits to the physician and had 145 fine needle aspiration biopsies, 70 mammograms, and 28 surgical biopsies, and after six months 73% (107/147) were declared cancer free. The follow up costs of the false positive screening results were Kr2.54m (250,000 pounds) in the first round and Kr0.85m (84,000 pounds) in the second round. Women under 50 accounted for about 41% of these costs. CONCLUSIONS: The examinations and investigation carried out after false positive mammography --especially in women under 50--and the cost of these procedures are a neglected but substantial problem.     

Sequential assignment of 1H, 13C and 15N resonances of human carbonic anhydrase I by triple-resonance NMR techniques and extensive amino acid-specific 15N-labeling

Summary The backbone NMR resonances of human carbonic anhydase I (HCA I) have been assigned. This protein is one of the largest monomeric proteins assigned so far. The assignment was enabled by a combination of 3D triple-resonance experiments and extensive use of amino acid-specific ¹⁵N-labeling. The obtained resonance assignment has been used to evaluate the secondary structure elements present in solution. The solution structure appears to be very similar to the crystal structure, although some differences can be observed. Proton-deuteron exchange experiments have shown that the assignments provide probes that can be used in future folding studies of HCA I.The chemical shift data have been deposited in the BioMagResBank in Madison, WI, U.S.A.