DNA methylation is not involved in the structural alterations of Ornithine Decarboxylase or Total Chromatin of c-Ha-rasVal 12 Oncogene-Transformed NIH-3T3 Fibroblasts

The ornithine decarboxylase (odc) gene is an early response gene, whose increased expression and relaxed chromatin structure is closely coupled to neoplastic growth. In various tumour cells, the odc gene displays hypomethylation at the sequences CCGG. Hypomethylation of genes is believed to correlate with chromatin decondensation and gene expression. Since a given pattern of DNA methylation may not be preserved in neoplastic cells, we studied the methylation status of odc gene at the CCGG sequences in c-Ha-ras^{Val 12} oncogene-transformed NIH-3T3 fibroblasts during the growth cycle and relative to their normal counterparts. We found that the methylation state of the odc gene and its promoter and mid-coding and 3' regions remain unaltered during the cell cycle. We also found that in ras oncogene-transformed cells, which display a more decondensed nucleosomal organization of chromatin than the normal cells, the CCGG sequences in bulk DNA and at the odc gene were methylated to the same extent as in the nontransformed cells. These data suggest that DNA hypomethylation at the CCGG sequences is not a prerequisite for chromatin decondensation and cell transformation by the c-Ha-ras^{Val 12} oncogene.     

Microhabitat use and behavior of voles under weasel and raptor predation risk: predator facilitation?

An example of predator facilitation is that a microhabitat shiftin a prey species induced by one predator increases the probabilityof the prey falling victim to other predators. Least weasels(Mustela nivalis) hunt in dense plant cover, whereas kestrels(Falco tinnunculus) hunt in habitats with sparse plant cover.Field voles (Microtus agrestis), the main food of weasels andkestrels, prefer open country with a high grass layer. We simulateda multipredator environment in an aviary (3.0 x 4.8 x 2.2 m)to find out whether predator facilitation plays a role in theinteractions between voles, small mustelids, and raptors. Ineach replicate, we placed a field vole in a pen including sidesof high and low grass layers (cover and open). In a predator-freesituation, voles preferred cover but shifted to open when aweasel was introduced to cover. In the presence of a kestrel,voles occupied cover and decreased their mobility. In the presenceof a weasel plus a kestrel, voles behaved as under the kestrelrisk alone. Therefore, in these aviary circumstances, volesperceived the kestrel risk as greater than the weasel risk.Predator facilitation in the assemblage of predators subsistingon rodent prey may contribute to the crash of the four-yearvole cycle: microhabitat shift due to an avoidance of weaseljaws may drive voles to raptor talons.     

Low heritability in morphological characters of Tengmalm's owls: The role of cyclic food and laying date?

Summary In parent—offspring regressions, high heritability estimates of characters may simply be due to common environment: the resemblance between the living conditions of parents and their offspring in species showing restricted natal dispersal. In vole-eating Tengmalm's owls (Aegolius funereus), the natal dispersal and breeding dispersal of adult females are wide (up to > 1000 km and > 500 km, respectively), whereas adult males are resident. We found that body measurements of 183 recruits born in western Finland were independent of parental age and vole abundance in the birth year. Early-laid eggs produced longer winged recruits than late-laid eggs. The wing lengths of the daughters showed a significant positive regression on the wing length of their mothers, but the removal of the maternal effect via laying date lowered this relationship. The development time of offspring to the first autumn might also be crucial for morphological characters of females in their later life. Significant regressions were not found between the wing length of the son and his father. The mother—daughter regression was small for laying date, but positive (p = 0.08) for clutch size. These results suggest low heritability in breeding and morphological characters of owls and this low heritability may enable plastic adjustment to optimize fitness at any stage in a fluctuating environment. Nonadditive genetic variance also creates variation between offspring characters that are not genetically correlated with the parents and may explain these low heritability estimates.     

Spatial synchrony in vole population fluctuations – a field experiment

Three mechanisms have been proposed to induce spatial synchrony in fluctuations of small mammal populations: climate‐related environmental effects, predation and dispersal. We conducted a field experiment in western Finland to evaluate the relative roles of these mechanisms in inducing spatial synchrony among cyclic populations of field voles Microtus agrestis. The study was conducted during the increase and peak phases of a vole population cycle on four agricultural field sites situated 1.5–7.0 km apart. Each field contained two 0.5‐ha fenced enclosures and one 1‐ha unfenced control area. One enclosure per field allowed access by small mustelid predators and the other by avian predators; all enclosures prevented the dispersal of voles. The unfenced control areas allowed access by all predators as well as dispersal by voles. Enclosed vole populations were in a treatment‐wise asynchronous phase before the predator access treatments were applied. The growth rates of all enclosed populations were tightly synchronized during the course of the experiment. Conversely, synchrony both among the unfenced populations and between the fenced and unfenced populations was practically non‐existent. During winter, in the increase phase of the cycle, vole populations in all treatments declined to low densities due to a seasonal effect of winter food depletion. During summer, in the peak year of the vole cycle, all populations fluctuated in synchrony. At this time, both small mustelids and birds of prey appeared to be abundant enough to induce synchrony. Dispersal was identified as a potential contributor to synchronization, but the magnitude of its effects could not be reliably discerned. Our results indicate that no single mechanism can account for the observed patterns of spatial synchrony among cyclic northern vole populations. Rather, spatial synchronization is induced by different mechanisms, namely seasonality and predation, acting successively during different seasons and phases of the vole cycle.     

Maternal transfer of androgens in eggs is affected by food supplementation but not by predation risk

Mothers may affect the future success of their offspring by varying allocation to eggs and embryos. Allocation may be adaptive based on the environmental conditions perceived during early breeding. We investigated the effects of food supplementation and predation risk on yolk hormone transfer in the pied flycatcher Ficedula hypoleuca. In a food supplementation experiment, females were food‐supplemented prior to and during egg‐laying and androgen concentrations were measured throughout the laying order. Predation risk was investigated in three different studies combining both correlative data, where flycatchers bred in close proximity to two different predator species that prey upon adult flycatchers (either Tengmalm's owl Aegolius funereus or pygmy owl Glaucidium passerinum), and an experimental manipulation, where flycatchers were exposed to cues of a nest predator (least weasel Mustela nivalis). Females receiving food supplementation laid eggs with lower concentrations of androstenedione (A4) than females not receiving food supplements. Yolk testosterone (T) concentration showed the same pattern but the difference was not statically significant. Testosterone (but not A4) concentration increased within clutches, from the first to the last egg, independently of the food supplementation. Females breeding under high predation risk did not differ from control females in their yolk androgen levels (A4, T or progesterone). However, concentrations of A4 tended to be lower in the proximity of pygmy owls, which could indirectly increase offspring survival after fledging. Food supplementation during egg‐laying seems to have a stronger impact on maternal transfer of androgens than predation risk. Food availability and predation risk could differentially affect the trade‐offs of androgen allocation for the offspring when raised in good vs. dangerous environments.     

Cystic fibrosis in Finland: a molecular and genealogical study

Summary The incidence of cystic fibrosis (CF) in Finland is one tenth that in other Caucasian populations. To study the genetics of CF in Finland, we used a combined molecular and genealogical approach. Out of the 20 Finnish families with a living CF patient, 19 were typed for eight closely linked restriction fragment length polymorphisms (RFLP) at the MET, D7S8, and D7S23 loci. The birthplaces of the parents and grandparents were traced using population registries. Allele and haplotype frequencies in Finland are similar to those of other European and North American populations, but are modified by sampling: two regional CF gene clusters, evidently the results of a founder effect, were identified. Generally, the gene was evenly distributed over the population, carrier frequency being estimated at approximately 1.3%. We conclude that CF in Finland is caused by the common Caucasian mutation(s), and that the low frequency of the gene can be explained by a negative sampling effect and genetic drift.     

Analysis of purine and pyrimidine bases,ribonucleosides, and ribonucleotides by high-pressure liquid chromatography

A high-pressure liquid chromatographic method has been developed for the separation and quantitation of purine and pyrimidine bases, ribonucleosides, and ribonucleotides. The procedure is carried out on a 1.8 × 700-mm column packed with Aminex-A-25 anion-exchange resin. The column is eluted with a linear gradient of ammonium chloride. The elution buffer contained borate also to complex the sugar phosphates and ethanol to improve the separation of bases and nucleosides. The analysis is completed in about 160 min. The potential application of this method for the quantitation of acid-soluble metabolites in fibroblasts is described.     

Iodinated melatonin: preparation and characterization of the molecular structure by mass and 1H NMR spectroscopy

Synthetic melatonin was iodinated by treatment with potassium iodide in the presence of an oxidizing agent, Iodo-Gen. The iodination products of melatonin were extracted with chloroform and separated by HPLC. The fraction showing immunoreactivity with respect to melatonin antisera was characterized as iodomelatonin by mass spectrometry, so that the substitution of iodine had occurred at a ring carbon atom. 1H NMR spectra showed the iodine to be incorporated at the C-2 position of the indole moiety. The N-[2-(2-iodo-5-methoxy-1H-indol-3-yl)ethyl]acetamide (2-iodomelatonin) reported here is more useful than [3H]melatonin as a tracer in melatonin radioimmunoassay. This method offers also the possibility of preparing iodinated serotonin and other indoleamines for biological studies.     

Breeding biology of the Siberian TitParus cinctus in Finland

The breeding biology of the Siberian Tit was studied in several areas within the whole breeding range of this species in Finland. A total of about 920 nests came to our knowledge. The breeding densities exceeded 4 pairs/km² in best habitats and the population decline since the 1940s has not been as marked as suspected. The onset of laying did not vary much between the study areas. The mean at Kuusamo (southern edge of the range) was 18 May, and 22 May at Kilpisjärvi where the environment is harshest. The mean clutch size was 7.94 with moderate geographic variation, but no clear geographical trends. No genuine second clutches have ever been recorded in the Siberian Tit. The breeding success (number of young fledging of number of eggs laid) varied between 60 and 87 % being highest at Kuusamo and lowest at Kilpisjärvi.

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Zusammenfassung Die Brutbiologie der Lapplandmeise wird nach Untersuchungen in verschiedenen Gebieten ihres Areals in Finnland beschrieben. Ausgewertet werden Daten von insgesamt 920 Nestern. In den besten Habitaten ist mit einer Dichte über 4 Paaren/km² zu rechnen; die Abnahme seit den 40er Jahren war offenbar nicht so stark wie bisher vermutet. Der Legebeginn variierte zwischen den Untersuchungsgebieten nicht sehr deutlich. Der Mittelwert fällt am Südrand des Areals bei Kuusamo auf den 18. Mai, bei Kilpisjärvi, dem rauhesten Gebiet, auf den 22. Die mittlere Gelegegröße betrug 7,9 Eier mit einer schwachen geographischen Variation, aber mit keinem deutlichen geographischen Trend. Sichere Zweitgelege wurden bis jetzt bei der Lapplandmeise nicht nachgewiesen. Der Bruterfolg (Zahl der flüggen Jungen im Vergleich zur Zahl der gelegten Eier) variierte zwischen 60 und 87 % und war am Südrand am höchsten. Einige Anpassungen der Lapplandmeise an rauhes nordisches Klima im Vergleich zu anderen Meisen werden diskutiert.