Nucleotide Metabolism during Pine Pollen Germination

The metabolism of purine- and pyrimidine nucleotides in pine pollen (Pinus mugo) grown in suspension cultures have been examined. In the ungerminated dehydrated pollen, the presence of ATP has been demonstrated. Incubation of the pollen in a germination medium leads to an exhaustion of the ATP pool, which is restored with the onset of oxygen uptake. By labelling pollen cultures with ³²P-orthophosphate, it has been possible to quantitate the nucleotide components of the pollen, and thereby to measure changes in the nucleotide pattern at various growth stages. The most marked changes occur during the initial phase of tube growth when a large increase in the ribonucleoside triphosphate and the sugar nucleotide pools is observed. The contents of ATP and UDP-glucose are further increased if starch synthesis is initiated by the addition of sucrose to the culture medium. In order to determine whether nucleotides in pine pollen are synthesized from de novo pathways or via reutilization pathways, from breakdown products of nucleic acids, pollen was incubated with ¹⁴C-labelled precursors of both the de novo and the reutilization pathways. Incorporation experiments established de novo synthesis of ATP and GTP from glycine, and de novo synthesis of CTP and UTP from orotic acid. The operation of pathways for the utilization of exogenous nucleosides was also demonstrated. While uridine, cytidine and adenosine are incorporated into nucleoside triphosphate to a great extent, only minor incorporation of inosine and guanosine is observed. These reutilization pathways might be of importance for the synthesis of nucleotides during tube growth in situ. Addition of inhibitors of glycolysis and oxidative phosphorylation drastically reduces the level of ribonucleoside triphosphates, indicating a rapid turnover of the nucleotide pool.     

Gibson's reclassification of the enoplan nemerteans (Enopla, Nemertea): a critique and cladistic analysis

Gibson's (1988) reclassification of the class Enopla (phylum Nemertea), and in particular the forming of the taxon Paramonostilifera, is assessed by a cladistic analysis based on 35 characters. This analysis does not support the reclassification, and it is suggested that the previous classification is kept for the time being, although it is recognized that certain of the higher categories are non-monophyletic and should be reclassified.     

Using Genetic Tools to Track Desert Bighorn Sheep Colonizations

ABSTRACT Understanding colonization is vital for managing fragmented populations. We employed mitochondrial DNA haplotypes and 14 microsatellite (nuclear DNA) markers to infer the origins of newly established populations of desert bighorn sheep (Ovis canadensis nelsoni) and to assess loss of genetic diversity during natural colonizations. We used haplotype distribution, F-statistics, Bayesian population clustering, and assignment tests to infer source populations for 3 recent colonies and identified a previously undetected colonization from multiple source populations. Allelic richness declined in 3 of 4 colonies in comparison to the primary source populations, but not as much as has been reported for translocated populations. Heterozygosity declined in only one colony. We also demonstrated that both native and translocated desert bighorn sheep have naturally recolonized empty habitats and suggest that colonization may partially offset population extinction in the region as long as connectivity is maintained. Genetic techniques and mitochondrial DNA haplotypes we described will allow managers to determine the origins of future colonizations by bighorn sheep in California, USA, and prioritize protection of linkages between known sources and colonies.     

Neumann’s Warbler Hemitesia neumanni (Sylvioidea): the sole African member of a Palaeotropic Miocene avifauna

We present molecular evidence that Neumann’s Warbler Hemitesia neumanni is deeply nested within the Cettiidae. The species’ distribution in the Albertine Rift of East Africa is intriguing, as the family Cettiidae is principally an Asian radiation. This disjunct distribution could be a result of colonization of Africa by long‐distance dispersal, or the Cettiidae may at some point in the past have had a much larger geographical distribution that also covered parts of Africa.     

Borrelia burgdorferi infection in Ixodes ricinus from habitats in Denmark

A total of 2647 ticks of the genus Ixodes was sampled by flagging the vegetation in thirty-one sites in eastern Jutland, Denmark. All ticks were identified as Ixodes ricinus Linnaeus. A total of 317 ticks (202 nymphs and 115 adults) from three different sites were examined for the spirochaete Borrelia burgdorferi Johnson et al. by indirect fluorescent antibody staining; the frequency of infection varied from 7% to 22%. It is concluded that I. ricinus, known to be the most common tick in Denmark, is the vector largely responsible for the transmission of B. burgdorferi in this country.     

The hunting habitats of Goshawks Accipiter gentilis in boreal forests of central Sweden

Radio-tracking was used to study the habitat utilization of hunting Goshawks Accipiter gentilis in central Swedish boreal forest. Data were collected during September-June, in 1977–1981. There was no major difference between autumn, winter or spring in any aspect of habitat preference, despite seasonal differences in prey composition. Despite the strong reversed sexual size-dimorphism, no habitat segregation between the sexes was found. It is argued that this is due to the lack of prey segregation between the sexes. Goshawks showed a strong preference for mature forest, which was chosen twice as often as would be expected from its prevalence in the environment, whereas the younger successional stages of the forest were under-used. Goshawks preferred large habitat patches, and showed no major preference with respect to tree species composition of the forest. Kills made by radio-tagged Goshawks showed the same habitat- and patch-size distribution as did Goshawk locations in general. It is argued that the profitability of different hunting habitats, and thus habitat preferences, is not only determined by prey density in the habitats, but also by other habitat features influencing the Goshawk's ability to hunt there. Winter home-ranges averaged 5700 ha, considerably larger than Goshawk ranges recorded in areas with richer prey supply.     

A new monostiliferous hoplonemertean (Nemertea), Oerstedia striata sp.n., from the west coast of Sweden

Oerstedia striata sp.n. (family Prosorhochmidae?) is described. The species was originally reported as one of the varieties of the polymorphic species Oerstedia dorsalis (Abildgaard, 1806). Its specific status was detected by an electrophoretic screening of six enzymes, of which four were unique for this species as compared to the analysed forms of O. dorsalis.     

A study of the diversity and geographical variation in numbers of leg‐bearing segments in centipedes (Chilopoda: Geophilomorpha) in north‐western Europe

Five species of geophilomorphs, Strigamia maritima (Leach, 1817), Geophilus flavus (De Geer, 1778), Geophilus truncorum Bergsøe and Meinert, 1866, Geophilus proximus C. L. Koch, 1847, and Pachymerium ferrugineum (C. L. Koch, 1835), from various sample sites in north‐western Europe were examined for numbers of leg‐bearing segments. Where data was adequate, mean segment numbers were correlated with latitudinal gradients for each species. Solely in S. maritima and some populations of P. ferrugineum did the results show a highly significant geographic pattern towards more leg‐bearing segments in southern populations of both sexes. As concerns G. proximus, we presented for the first time a remarkable geographic shift towards an increased number of pairs of legs in northern populations. Contrary to the conventional geographic pattern, we found that G. flavus and G. truncorum did not exhibit a north–south increase or decrease in segment number. Although there was no general/universal evidence supporting the occurrence of a significant regression slope between mean segment number and latitude/temperature, more information shows that the overall region‐to‐region segment variation was highly significant in both sexes. In S. maritima and P. ferrugineum mean segment number was correlated with the north–south temperature cline. The same was not observed in G. proximus. Parthenogenesis in G. proximus, and a series of ecological characteristics such as habitat preferences, spatial distribution, and fragmented populations could explain the presence or absence of a geographic patterning of segment number variation along a latitudinal cline. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 899–909.