Uterine and lung uteroglobins in the rabbit: Two similar proteins with differential hormonal regulation

Previous studies have shown that several rabbit tissues contain proteins which cross-react in the radioimmunoassay for uteroglobin, a progestin-regulated protein in rabbit uterus (Torkkeli et al. (1977) Mol. Cell. Endocrinol. 9, 101–118). In the present study, a uteroglobin-like protein was purified to an apparent homogeneity from an extra-uterine tissue, rabbit lung, by successive chromatographies on hydroxyapatite, Sephadex G-75, SP-Sephadex, DEAE-cellulose and CM-cellulose. The final preparation behaved homogeneously in various polyacrylamide gel electrophoretic systems and in isoelectric focusing. The uteroglobin-like protein isolated from the lung had very similar physico-chemical and immunological properties to those of uteroglobin present in the rabbit uterine fluid. The two proteins had: (i) the same molecular weight, of approx. 13 000, with a two subunit structure (each approx. M_r 7000); (ii) identical behavior in polyacrylamide gel electrophoresis under non-denaturing and denaturing conditions; (iii) the same isoelectric point at pH 5.4; (iv) absence of carbohydrate in the molecule; (v) very similar amino acid compositions; (vi) lack of tryptophan among the amino acids; (vii) the same N-terminal amino acid (glycine), and (viii) indistinguishable immunological characteristics. Collectively, these data strongly suggest that uterine and lung uteroglobins are identical proteins.In contrast to the induction of the uterine uteroglobin by steroids with progestational activity, the synthesis of extra-uterine uteroglobins was not affected by these steroid hormones to any major extent. In keeping with the concept that lung is a target tissue for glucocorticoid action, cortisol and dexamethasone were capable of increasing the concentration of lung uteroglobin 3-fold (from 3 to 9 μg/mg soluble protein). These compounds did not, however, alter the secretion of the uterine protein. Administration of high doses of testosterone and 5α-dihydrotestosterone elevated significantly the content of both uterine and lung uteroglobin. Only approx. one-fifth of the adult pulmonary uteroglobin levels were present in lungs of newborn rabbits indicating that developmental changes occur in the lung uteroglobin content.     

How Close Do We Live to Water? A Global Analysis of Population Distance to Freshwater Bodies

Traditionally, people have inhabited places with ready access to fresh water. Today, over 50% of the global population lives in urban areas, and water can be directed via tens of kilometres of pipelines. Still, however, a large part of the world''s population is directly dependent on access to natural freshwater sources. So how are inhabited places related to the location of freshwater bodies today? We present a high-resolution global analysis of how close present-day populations live to surface freshwater. We aim to increase the understanding of the relationship between inhabited places, distance to surface freshwater bodies, and climatic characteristics in different climate zones and administrative regions. Our results show that over 50% of the world''s population lives closer than 3 km to a surface freshwater body, and only 10% of the population lives further than 10 km away. There are, however, remarkable differences between administrative regions and climatic zones. Populations in Australia, Asia, and Europe live closest to water. Although populations in arid zones live furthest away from freshwater bodies in absolute terms, relatively speaking they live closest to water considering the limited number of freshwater bodies in those areas. Population distributions in arid zones show statistically significant relationships with a combination of climatic factors and distance to water, whilst in other zones there is no statistically significant relationship with distance to water. Global studies on development and climate adaptation can benefit from an improved understanding of these relationships between human populations and the distance to fresh water.     

An Integrated Understanding of the Rapid Metabolic Benefits of a Carbohydrate-Restricted Diet on Hepatic Steatosis in Humans

1. Download high-res image (291KB)
2. Download full-size image

     

Seasonal and regional variations in the feeding habits of the harbour seal, Phoca vitulina, in the Skagerrak and the Kattegat

Studies of the feeding of harbour seals have been carried out at the Tjärnö Marine Biological Laboratory since 1977. The studies are based on fish otoliths found in faeces at seal haulouts. The present paper compares feeding habitats at two different localities. Three families of fish, gadoids, pleuronectids and clupeoids were predominant in the seals' diet at a rocky shore habitat. Pleuronectids made up 75% of the diet at a sandy shore habitat. Temporal variations in feeding habits are also examined. The results indicate that harbour seals are opportunists in their choice of prey species, but some locally abundant species do not appear in their diet.     

Biology of human papillomavirus (HPV) infections and their role in squamous cell carcinogenesis

Current data implicating the role of human papillomavirus (HPV) infections in squamous cell carcinogenesis may be summarised as follows: animal models have shown that PVs can induce malignant transformation; HPV involvement in both benign and malignant human squamous cell tumours has been demonstrated by morphological, immunohistochemical and DNA hybridisation techniques; HPV infections in the genital tract are venereally transmitted and are associated with the same risk factors as cervical carcinoma; the natural history of cervical HPV lesions is similar to that of CIN, namely, they have the potential to develop into carcinoma in situ; malignant transformation of PV-induced lesions seems to depend on virus type and the physical state of its DNA, e.g., whether or not it is integrated in the host cell DNA; malignant transformation most probably requires synergistic actions between the PVs and chemical or physical carcinogens, or other infectious agents; genetic disposition (at least in animals) significantly contributes to malignant transformation; immunological defence mechanisms of the host are probably capable of modifying the course of PV infections (efficacy in man remains to be elucidated). Many details of the molecular mechanisms, however, still remain to be clarified. Although BPV1 is capable of transforming fibroblasts, the way that papillomaviruses transform epithelial cells is unclear. Which gene is capable of inducing the limited cell proliferation in benign lesions? No model systems exist to provide the answer nor to elucidate the progression to malignant cells and then to invasive cancer. Improved tissue culture systems for in vitro differentiation of keratinocytes should help in elucidating the biology of papillomaviruses and their interaction with cell division and differentiation.     

Isolation and Characterization of a Hantavirus from Lemmus sibiricus: Evidence for Host Switch during Hantavirus Evolution

A novel hantavirus, first detected in Siberian lemmings (Lemmus sibiricus) collected near the Topografov River in the Taymyr Peninsula, Siberia (A. Plyusnin et al., Lancet 347:1835-1836, 1996), was isolated in Vero E6 cells and in laboratory-bred Norwegian lemmings (Lemmus lemmus). The virus, named Topografov virus (TOP), was most closely related to Khabarovsk virus (KBR) and Puumala viruses (PUU). In a cross focus reduction neutralization test, anti-TOP Lemmus antisera showed titers at least fourfold higher with TOP than with other hantaviruses; however, a rabbit anti-KBR antiserum neutralized TOP and KBR at the same titer. The TOP M segment showed 77% nucleotide and 88% amino acid identity with KBR and 76% nucleotide and 82% amino acid identity with PUU. However, the homology between TOP and the KBR S segment was disproportionately higher: 88% at the nucleotide level and 96% at the amino acid level. The 3' noncoding regions of KBR and the TOP S and M segments were alignable except for 113- and 58-nucleotide deletions in KBR. The phylogenetic relationships of TOP, KBR, and PUU and their respective rodent carriers suggest that an exceptional host switch took place during the evolution of these viruses; while TOP and KBR are monophyletic, the respective rodent host species are only distantly related.     

Experimental revegetation of the regulated lake Ontojärvi in northern Finland

Water level regulation causes large-scale ecological changes in the littoral areas of lakes in northern Finland. If the summertime water level is raised, intensive erosion processes begin, causing a sudden decline in shore vegetation. The need for shore protection is obvious in areas of high recreational value. At lake Ontojärvi, planting experiments with littoral helophytes and bushes were carried out during the years 1990–92. All the experiments were carried out in the eroded sandy areas, which were partly protected by mechanical barriers. Several plant species were planted on the shore which had been treated with different peat mixtures, etc. The frequencies of the different species were followed monthly. After the first summer, the average survival rates were about 45 % due to the drying of seedlings. A rapid decrease in the survival rates took place during the high water level period in 1991 at which point only 20% of the planted individuals were alive. The best results were obtained for the helophyte Carex rostrata Stokes, of which 30% had survived erosion. Tall willows (Salix phylicifolia L.) were also erosion-resistant with a survival rate of 80%.     

Modelling species distribution in complex environments: an evaluation of predictive ability and reliability in five shorebird species

Aim  Many wader populations around the world are declining as a consequence of habitat degradation or loss. It is therefore important to identify species-specific habitat demands accurately and to define the important factors explaining species distribution, in order to develop tools that can be used in conservation planning. The aim of this study is to create reliable, functional and ecologically interpretable predictive distribution models for five breeding wader species.
Location  The archipelago of SW Finland in the Baltic Sea.
Methods  We used multivariate adaptive regression splines (MARS) to create single-species and multiresponse distribution models based on 525 study islands and 12 abiotic and biotic environmental variables. Model evaluation was carried out on independent data not used in model building (100 + 116 islands). The models were tested for discrimination with receiver-operating characteristic statistics and for calibration with Millers calibration statistics (MCS).
Results  The single-species models for the turnstone ( Arenaria interpres ), redshank ( Tringa totanus ) and oystercatcher ( Haematopus ostralegus ) showed good predictive abilities, regarding both discrimination and calibration, when evaluated on independent data. The multiresponse models for the less prevalent species, common sandpiper ( Actitis hypoleucos ) and the common ringed plover ( Charadrius hiaticula ) had better discriminative abilities than the single-species models. The most influential predictor overall was occurrence of small larids. Exposure, area of forest and low and flat areas were also important, as well as shore habitats.
Main conclusions  We found that the ability of MARS to fit non-linear and multiresponse models makes it a useful method to quantitatively relate species occurrence to environmental characteristics of a complex environment.