Sequencing of the mtDNA cytochrome b gene and reconstruction of the matriarchal relationships between wood and field mice of the genus Apodemus (Muridae, Rodentia)

The primary sequence of a 402-bp part of the cytochrome b gene was determined in nine species of wood and field mice of the genus Apodemus. The majority of mutations were synonymous. The total number of transitions exceeded than of transversions. Among all substitutions, C-T transitions prevailed (51%); the most common substitution type in genus-specific sites was C-A transversions (42%). In interpopulation analysis, only transitions were recorded. A phylogenetic tree, constructed with the use of the neighbor-joining method, showed that the genus Apodemus is divided into three highly divergent groups: south Asian (Apodemus argenteus, A. semotus), east Asian (A. speciosus, A. agrarius), and Eurocaucasian (A. sylvaticus, A. flavicollis, A. uralensis, A. ponticus, A. flavipectis). The mean genetic distances within each group were 12.6, 11.2, and 8.8%, respectively. The species of the first group are more remote genetically and ancestrally with regard to the other groups. The interspecies divergence estimated for A. speciosus ranged from 0.25 to 3.75%. Thus, the evolutionary age of the genus Apodemus is about 6 Myr, and time of divergence of A. speciosus populations is 0.1-1.5 Myr. The phylogeny inferred from the data on the sequence of the cytochrome b gene in Apodemus mtDNA is somewhat different from similar phylogenies based on other genetic data and from the zoological taxonomy of wood and field mice. However, the above classification of species is confirmed by features of their karyotypes and segmentation of satDNA, and by the RFLP of total nDNA and isozyme polymorphism. Our results are in good agreement with the new classification of wood and field mice recently proposed by Russian zoologists.     

A molecular perspective on the systematics and evolution of the genus Arvicanthis (Rodentia, Muridae): inferences from complete cytochrome b gene sequences

Systematics of the genus Arvicanthis, the African unstriped grass rat, are somewhat controversial. Most recent taxonomic revisions list five to six species but the definition of some of these (Arvicanthis dembeensis, Arvicanthis nairobae, and Arvicanthis niloticus) is uncertain. The complete mitochondrial cytochrome b gene (1140 bp) was sequenced for 20 specimens from throughout the range of the genus to determine the intrageneric genetic structure, construct a molecular phylogeny, and evaluate classical taxonomies. Neighbor-joining and maximum parsimony analyses yielded identical phylogenetic trees that identify two major lineages: the first one (1) is composed of specimens usually referred to A. niloticus but representing several distinct species, and the other (2) is a complex including "true" A. niloticus from Egypt and northern West Africa as well as Arvicanthis abyssinicus, Arvicanthis dembeensis, and Arvicanthis somalicus. An analysis on a 357-bp fragment of the cytochrome b including published data on A. nairobae indicates that this taxon is part of clade (1). Calibration of the number of 3rd position transversion changes with the murid fossil record suggests that clades (1) and (2) diverged approximately 5 Myr ago. Arvicanthis niloticus as currently recognized is a paraphyletic association and this name should be restricted to the Egyptian and northern West African sample. We also suggest referring to A. dembeensis as A. niloticus, as our cytochrome b data do not support its recognition as a distinct species. Clade (1) is subdivided in three lineages, geographically corresponding to southern West, Central, and East Africa. The high genetic divergence detected between the Central African lineage and the other two lineages suggests that they probably represent separate species. Clade (2) experienced rapid cladogenetic events during the late Pliocene, with the A. somalicus lineage being the first to emerge, followed by the ancestor of A. abyssinicus and A. blicki. This period was characterized by significant climatic and environmental changes, such as the extension of open habitats, which might have provided a stimulus for speciation in this savanna-dwelling genus. Confrontation of our molecular results with chromosomal data shows a high degree of congruence between the two datasets.     

Molecular phylogeny of the nuclear 5.8S ribosomal RNA genes in 37 species of Nicotiana genus

Solid-phase synthesis of a 300-member pharmacophore library of 1,4-dihydropyridines from keto ester, diketone and aldehyde building blocks on a cleavable amine polymeric support is described. Screening and serial deconvolution of the combinatorial library has resulted in identification of known and new potent calcium channel blockers.     

Molecular phylogeny of the New World monkeys (Platyrrhini, primates) based on two unlinked nuclear genes: IRBP intron 1 and epsilon-globin sequences

Nuclear sequences of the 1.8 kilobase (kb) long intron 1 of the interstitial retinol-binding protein gene (IRBP), previously determined for 11 of the 16 extant genera of New World monkeys (superfamily Ceboidea, infraorder Platyrrhini), have now been determined for the remaining 5 genera. The maximum parsimony trees found, first with IRBP sequences alone and then with tandemly combined IRBP and epsilon-globin gene sequences from the same species, supported a provisional cladistic classification with the following clusters. Subtribes Callitrichina (Callithrix, Cebuella), Callimiconina (Callimico), Leontopithecina (Leontopithecus) and Saguina (Saguinus) constitute subfamily Callitrichinae, and subfamilies Callitrichinae, Aotinae (Aotus), and Cebinae (Cebus, Saimiri) constitute family Cebidae. Subtribes Chiropotina (Chiropotes, Cacajao) and Pitheciina (Pithecia) constitute tribe Pitheciini; and tribes Pitheciini and Callicebini (Callicebus) constitute subfamily Pitheciinae. Subtribes Brachytelina (Brachyteles, Lagothrix) and Atelina (Ateles) constitute tribe Atelini, and tribes Atelini and Alouattini (Alouatta) constitute subfamily Atelinae. The parsimony results were equivocal as to whether Pitheciinae should be grouped with Atelinae in family Atelidae or have its own family Pitheciidae. The cladistic groupings of extant ceboids were also examined by different stochastic evolutionary models that employed the same stochastic process of nucleotide substitutions but alternative putative phylogenetic trees on which the nucleotide substitutions occurred. Each model, i.e., each different tree, predicted a different multinomial distribution of nucleotide character patterns for the contemporary sequences. The predicted distributions that were closest to the actual observed distributions identified the best fitting trees. The cladistic relationships depicted in these best fitting trees agreed in almost all cases with those depicted in the maximum parsimony trees.     

Molecular phylogeny and ecological diversification in a clade of New World songbirds (genus Vireo)

We constructed a molecular phylogeny for a clade of eye-ringed vireos (Vireo flavifrons and the V. solitarius complex) to examine existing hypotheses of speciation and ecological diversification. Complete sequences of the mtDNA cytochrome b gene were obtained from 47 individuals of this group plus four vireonid outgroups. Mean levels of sequence divergence in the clade varied from 0.29% to 5.7%. Differences were greatest between V. flavifrons and four taxa of 'V. solitarius'. The latter separated into three taxonomic, geographical and ecological groups: V. plumbeus plumbeus, V. cassinii cassinii, and V. solitarius solitarius plus V. solitarius alticola. These differed by an average of 2.6-3.2%. Populations within each group revealed low levels of sequence variation (x = 0.20%) and little geographical structuring. The mtDNA data generally corroborate results from allozymes. V. plumbeus shows a loss of yellow-green carotenoid pigmentation from the ancestral condition. The occupancy of relatively dry habitats by this species and V. cassinii represents a derived ecological shift from more-humid environments occupied by other species of vireonids. Ecological divergence in this clade occurred in allopatry and is associated with generic-level stability in morphometrics and foraging styles. Migratory behaviour and seasonal habitat shifts apparently evolved multiple times in vireos breeding in temperate environments. Present geographical and ecological distributions, and low levels of intrataxon genetic divergence, are hypothesized to be the result of postglacial regionalization of climate-plant associations and rapid northward expansion of breeding ranges.     

Molecular phylogeny of the families Campulidae and Nasitrematidae (Trematoda) based on mtDNA sequence comparison

The heavy and light chains of IgG monoclonal antibodies (mAbs) can be shown to be heterogeneous, with respect to isoelectric points, when analyzed by two-dimensional electrophoresis (2-DE). The molecular basis for this charge heterogeneity has not been clearly defined but it has been suggested that it could be due, in part, to differences in glycosylation. To investigate this possibility we have compared the 2-DE pattern of glycosylated and aglycosylated forms of the mouse IgG1 mAb (1B7-11), produced in vitro in the presence and absence of tunicamycin. Charge heterogeneity was shown not to be a consequence of glycosylation status. Intracellular and secreted IgG mAbs were also analyzed to investigate the time course of change in charge properties of the heavy and light chains. The charge heterogeneity was found to be generated intracellularly, and alterations in charge properties could be induced during incubation under physiological conditions. Semilogarithmic plots of the density of the principal heavy and light chain spots against incubation time showed linear relationships, suggesting that the charge shifts result from a first-order reaction. The semilogarithmic plot for the light chain correlated well with the time after IgG synthesis. These results suggest that the charge heterogeneity of an IgG mAb is due to intra- and extracellular modifications of the polypeptide chains which reflect "aging" of antibody molecules.     

DNA, morphology and fossils: phylogeny and evolutionary rates of the gastropod genus Littorina

Using data from the direct sequencing of fragments of three mitochondrial genes (12S and 16S ribosomal RNA, and cytochrome-b; total length 1469 b.p.) we have reconstructed a gene phylogeny for all 19 living species of the gastropod genus Littorina. Members of the closely related genera Nodilittorina, Littoraria and Mainwaringia have been used as outgroups, and it appears that Littorina is monophyletic. An earlier morphological phylogeny has been revised, and its topology found to be almost entirely consistent with that from the molecular data. The fossil record is sparse, but likewise consistent. A consensus tree is presented, showing clear resolution of basal and terminal branches, and a central unresolved polychotomy. We have used fossil evidence and geological events to estimate the ages of some clades, and thus to calculate average rates of molecular evolution, which in turn provide approximate dates for all branches of the molecular phylogeny. The central polychotomy may be explained by a burst of rapid speciation in the northwestern Pacific during the Middle Miocene, perhaps driven by climatic fluctuation. Our results support the hypothesis that the two clades of Littorina in the northern Atlantic originated from Pacific ancestors which took part in the Pliocene trans-Arctic migration of marine organisms.     

Molecular phylogeny of extant gymnosperms and seed plant evolution: analysis of nuclear 18S rRNA sequences

To study the evolutionary relationships among the four living gymnosperm orders and the interfamilial relationships in each order, a set of 65 nuclear 18S rRNA sequences from ferns, gymnosperms, and angiosperms was analyzed using the neighbor-joining and maximum-parsimony methods. With Selaginella as the outgroup, the analysis strongly indicates that the seed plants form a monophyletic group with the ferns as a sister group. Within the seed plants the angiosperms are clearly a monophyletic group. Although the bootstrap support for the monophyly of the gymnosperm clade is moderate, the monophyly is further supported by its lack of angiosperm-specific indels. Within the gymnosperms there appear to be three monophyletic clades: Cycadales-Ginkgoales, Gnetales, and Coniferales. The cycad-ginkgo clade is the earliest gymnosperm lineage. Given the strong support for the sister group relationship between Gnetales and Coniferales, it is unlikely that Gnetales is a sister group of the angiosperms, contrary to the view of many plant taxonomists. Within Coniferales, Pinaceae is monophyletic and basal to the remaining conifer families, among which there are three monophyletic clades: Phyllocladaceae-Podocarpaceae, Araucariaceae, and Sciadopityaceae-Taxaceae-Cephalotaxaceae-Taxodiacea e-Cupressaceae. Within the latter clade, Sciadopityaceae may be an outgroup to the other four families. Among the angiosperms, no significant cluster at the level of subclass was found, but there was evidence that Nymphaeaceae branched off first. Within the remaining angiosperms, the monocots included in this study are nested and form a monophyletic group. This study attests to the utility of nuclear 18S rRNA sequences in addressing relationships among living gymnosperms. Considerable variation in substitution rates was observed among the ferns and seed plants.     

Molecular phylogeny of rodents, with special emphasis on murids: evidence from nuclear gene LCAT

Phylogenetic relationships among 19 extant species of rodents, with special emphasis on rats, mice, and allied Muroidea, were studied using sequences of the nuclear protein-coding gene LCAT (lecithin:cholesterol acyltransferase), an enzyme of cholesterol metabolism. Analysis of 705 base pairs from the exonic regions of LCAT confirmed known groupings in and around Muroidea. Strong support was found for the families Sciuridae (squirrel and marmot) and Gliridae (dormice) and for suprafamilial taxa Muroidea and Caviomorpha (guinea pig and allies). Within Muroidea, the first branching leads to the fossorial mole rats Spalacinae and bamboo rats Rhizomyinae. The other Muroidea appear as a polytomy from which are issued Gerbillinae (gerbils), Murinae (rats and mice), Sigmodontinae (New World cricetids), Cricetinae (hamsters), and Arvicolinae (voles). Evidence from LCAT sequences agrees with that from a number of previous molecular and morphological studies, both concerning branching orders inside Muroidea and the bush-like radiation of rodent suprafamilial taxa (caviomorphs, sciurids, glirids, muroids), thus suggesting that this nuclear gene is an appropriate candidate for addressing questions of rodents relationships.     

Evolutionary relationships among members of the genus Chlamydia based on 16S ribosomal DNA analysis

Nucleotide sequences from strains of the four species currently in the genus Chlamydia, C. pecorum, C. pneumoniae, C. psittaci, and C. trachomatis were investigated. In vitro-amplified RNA genes of the ribosomal small subunit from 30 strains of C. pneumoniae and C. pecorum were subjected to solid-phase DNA sequencing of both strands. The human isolates of C. pneumoniae differed in only one position in the 16S rRNA gene, indicating genetic homogeneity among these strains. Interestingly, horse isolate N16 of C. pneumoniae was found to be closely related to the human isolates of this species, with a 98.9% nucleotide similarity between their 16S rRNA sequences. The type strain and koala isolates of C. pecorum were also found to be very similar to each other, possessing two different 16S rRNA sequences with only one-nucleotide difference. Furthermore, the C. pecorum strains truncated the 16S rRNA molecule by one nucleotide compared to the molecules of the other chlamydial species. This truncation was found to result in loss of a unilaterally bulged nucleotide, an attribute present in all other eubacteria. The phylogenetic structure of the genus Chlamydia was determined by analysis of 16S rRNA sequences. All phylogenetic trees revealed a distinct line of descent of the family Chlamydiaceae built of two main clusters which we denote the C. pneumoniae cluster and the C. psittaci cluster. The clusters were verified by bootstrap analysis of the trees and signature nucleotide analysis. The former cluster contained the human isolates of C. pneumoniae and equine strain N16. The latter cluster consisted of C. psittaci, C. pecorum, and C. trachomatis. The members of the C. pneumoniae cluster showed tight clustering and strain N16 is likely to be a subspecies of C. pneumoniae since these strains also share some antigenic cross-reactivity and clustering of major outer membrane protein gene sequences. C. psittaci and strain N16 branched early out of the respective cluster, and interestingly, their inclusion bodies do not stain with iodine. Furthermore, they also share less reliable features like normal elementary body morphology and plasmid content. Therefore, the branching order presented here is very likely a true reflection of evolution, with strain N16 of the species C. pneumoniae and C. psittaci forming early branches of their respective cluster and with C. trachomatis being the more recently evolved species within the genus Chlamydia.     

Taxonomy of ticks of the genus Microtimyobia (Acariformes: Myobiidae: Radfordia) and their distribution on voles (Rodentia: Cricetidae: Arvicolinae)

A phylogenetic system of the subgenus Microtimyobia (Myobiidae: Radfordia) elaborated for the first time by means of the software HENNIG-86 is proposed. The subgenus Microtimyobia including three species groups, lemnina, hylandi and zibethicalis, was divided for a cladistic analysis into 6 operation units based mainly on a male genital shield structure. The analysis shows, that the zibethicalis group is a polyphyletic, while the hylandi and lemnina groups are monophyletic. Host-parasite associations of myobiid mite taxa with vole taxa (Arvicolinae) and some peculiarities of mite and host taxa distribution are analysed. The zibethicalis group is represented by two species, associated with the North American rodents of the genera Ondatra and Phenacomys respectively. The hylandi group are most widely distributed among Arvicolinae taxa, both in Eurasia and North America. However, R. hylandi occurs on those vole species of the genera Microtus and Pitymys, which are distributed only in central and southern parts of North America and represent descendants of the earlier migration wave of Microtus from the Eurasia. As far as R. hylandi is also found in the pleistocenus of the Yakutia, that means that its areal was wider than in recent period. The lemnina group lives on hosts of 2 subtribes of the tribe Arvicolini (Arvicolina and Clethrionomyina) and is restricted to Eurasian range, except R. lemnina. This species is also mainly distributed on Eurasian vole species, however it occurs on vole species distributed in Alaska and being decendants of the later wave of Microtus migration. As far as R. lemnina and R. hylandi are associated with representatives of different migration waves of Microtus from the Euroasia, it is suggested that mites of the hylandi group are the original myobiid fauna of the Microtus voles. The species of the lemnina group had apparently originated on voles of the subtribe Clethrionomyina and then migrated onto phylogenetically young hosts of the subtribe Arvicolina (Euroasian species of the Microtus and related genera), where they probably eliminated mites of the hylandi group from these hosts in Euroasia. The recent pattern of myobiid species distribution on vole species is a result of both a mite cospeciation with their hosts and a shift of hosts. Five new myobiid mite species are described and distinguished by characters as follows. R. (M.) abramovi sp. n. from Phodopus roborovskii (Cricetidae) is closely related to R. (M.) triton Fain et Lukoschus, 1977. In both sexes of the new species setae cxI 1, 2 are scale-shaped, while in R. (M.) triton these setae (cxI 1, 2) are hair-like. R. (M.) stekolnikovi sp. n. from Chionomys nivalis (type host) and Ch. gud is similar to R. (M.) lemnina (Koch, 1841). Females of new species have setae ra with 2 apical processes; female tritonymphs with long whip-like setae ic4. R. (M.) lemnina females have setae ra with 3 processes; female tritonymphs with short hair-like setae ic4. R. (M.) stenocrani sp. n. from Microtus gregalis is also closely related to R. (M.) lemnina. Females of the new species have setae ra with 2 processes; female tritonymphs with whip-like setae ic3. R. (M.) lemnina females have seate ra with 3 processes, female tritonymph with short hair-like setae ic3. R. (M.) synaptomysi sp. n. (ABSTRACT TRUNCATED)     

Multiregional introgressions inferred from the mitochondrial DNA phylogeny of a hybridizing species complex of gobiid fishes, genus Tridentiger

Partial sequences of the cytochrome b gene (402 bp) in mtDNA were determined for brackishwater gobiid fishes, genus Tridentiger, collected from geographically distant locations in the Japanese Archipelago, and their interspecific and geographic variations were analyzed and compared. Contrary to the results of a previous allozyme analysis which revealed the existence of considerable genetic divergence (Nei's genetic distance > 0.5) between T. obscurus and T. brevispinis, the mtDNA haplotypes (mitotypes) of these two species were very similar and could not be distinguished by any of the neighbor-joining, maximum-likelihood or parsimony analyses. Hybrid individuals between the two species were also found, with several mitotypes being shared by both species and their hybrids. The phylogenetic relationships of mitotypes were divided into three subgroups, the geographical distributions of the latter being allied to geographical features of the Archipelago. These results suggested the occurrence of multiregional introgression between the two species, with mitotypes transferring from one species to the other.     

Karyotype of the giant mole-rat, Cryptomys mechowi (Rodentia, Bathyergidae)

The karyotype of the giant mole-rat, Cryptomys mechowi (Rodentia, Bathyergidae), from Zambia was investigated in one male and one female by means of G-, C-, and AgNOR-banding techniques. The diploid chromosomal set consisted of 40 biarmed chromosomes (2n = 40, NF = 80). A pair of autosomes in the male and the X chromosomes in the female were heteromorphic. The sex chromosomes were unusually large.     

Phylogeny of the Drosophila saltans species group based on combined analysis of nuclear and mitochondrial DNA sequences

Nucleotide sequences from two nuclear loci, alcohol dehydrogenase and internal transcribed spacer-1 of the nuclear ribosomal DNA repeats, and two mitochondrial genes, cytochrome oxidase I and cytochrome oxidase II, were determined from nine species in the Drosophila saltans species group. The partition homogeneity test and partitioned Bremer support were used to measure incongruence between phylogenetic hypotheses generated from individual partitions. Individual loci were generally congruent with each other and consistent with the previously proposed morphological hypothesis, although they differed in level of resolution. Since extreme conflict between partitions did not exist, the data were combined and analyzed simultaneously. The total evidence method gave a more resolved and highly supported phylogeny, as indicated by bootstrap proportions and decay indices, than did any of the individual analyses. The cordata and elliptica subgroups, considered to have diverged early in the history of the D. saltans group, were sister taxa to the remainder of the saltans group. The sturtevanti subgroup, represented by D. milleri and D. sturtevanti, occupies an intermediate position in this phylogeny. The saltans and parasaltans subgroups are sister clades and occupy the most recently derived portion of the phylogeny. As with previous morphological studies, phylogenetic relationships within the saltans subgroup were not satisfactorily resolved by the molecular data.     

Coevolution of the Monogenoidea (Platyhelminthes) based on a revised hypothesis of parasite phylogeny

A revised hypothesis for the phylogeny of the Subclass Polyonchoinea (Monogenoidea) was constructed employing phylogenetic systematics. The Acanthocotylidae (formerly of the Order Capsalidea) is transferred to the Order Gyrodactylidea based on this analysis. The new phylogeny is used to determine coevolutionary relationships of the familial taxa of Monogenoidea with their hosts. The coevolutionary analysis suggests that the Monogenoidea apparently underwent sympatric speciation or dispersal while parasitic on ancestral Gnathostomata, resulting in two primary clades: the Polyonchoinea and the Oligonchoinea + Polystomatoinea. The two parasite clades apparently cospeciated independently with divergence of the Chondrichthyes and Osteichthyes. In the Polyonchoinea, the clade associated with Chondrichthyes experienced primary extinction within the Holocephala, but coevolved into the Loimoidae and Monocotylidae in the Galeomorphii and Squalea (Elasmobranchii), respectively. Within the Osteichthyes, polyonchoineans experienced primary extinction with the divergence of Sarcopterygii, Polypteriformes and Acipenseriformes. They demonstrate primary dispersal from the Neopterygii into the Squalea (as Amphibdellatinea), Actinistia (as Neodactylodiscinea) and Urodela (as Lagarocotylidea). Secondary dispersals of polyonchoineans occurred in the Gyrodactylidae to the Polypteriformes, Urodela and Anura; in the Acanthocotylidae to the Myxinoidea and Squalea; in the Capsalidae to the Acipenseriformes and Elasmobranchii; and in the Monocotylidae to the Holocephala. The Oligonchoinea and Polystomatoinea developed upon divergence of the Chondrichthyes and Osteichthyes. Oligonchoineans cospeciated within the Chondrichthyes, with the Chimaericolidea developing within the Holocephala and the ancestor of the Diclybothriidea + Mazocraeidea within the Elasmobranchii. Two cases of primary dispersal occurred within this clade: the Diclybothriidae to the Acipenseriformes and the ancestor of mazocraeidean families to the Neopterygii (both Osteichthyes). Secondary dispersal within the Oligonchoinea includes host switching of the common ancestor of Callorhynchocotyle (Hexabothriidae) to the Holocephala. Polystomatoineans coevolved within the Osteichthyes, but experienced primary extinctions in the Actinopterygii, Actinistia, Dipnoi and Amniota. Coevolution of the Sphyranuridae and Polystomatidae occurred with divergence of the Urodela and Anura, respectively. Secondary dispersal of Polystomatids to the Urodela, Dipnoi and Amniota is suggested. A preliminary phylogenetic analysis of the Polystomatoinea suggests that primary extinction with secondary dispersal of polystomatids to the Dipnoi may not be necessary to explain extant parasite distributions, since Concinnocotyla (Concinnocotylinae) appears to represent the sister taxon of the remaining Polystomatidae + Sphyranuridae.     

The genetic relationship between the Finns and the Finnish Saami (Lapps): analysis of nuclear DNA and mtDNA

The genetic relationships between two Finno-Ugric-speaking populations, the Finns and the Finnish Saami (Lapps), were studied by using PCR for six nuclear-DNA marker loci, mitochondrial restriction-site polymorphism, and sequence variation of a 360-bp segment of the mitochondrial control region. The allele frequencies of each of the nuclear-DNA marker loci and the frequencies of mtDNA restriction haplotypes were significantly different between the populations. The Saami showed exceptionally low variation in their mtDNA restriction sites. The 9-bp deletion common in East Asian populations was not observed, nor did the haplotype data fit into the haplogroup categorization of Torroni et al. The average number of nucleotide substitutions from the mtDNA haplotype data indicated that the Finnish Saami may be closer to the Finns than to the other reference populations, whereas nuclear DNA suggested that the Finns are more closely related to the European reference populations than to the Finnish Saami. The similarity of the Finns to the other Europeans was even more pronounced according to the sequence data. We were unable to distinguish between the Finns and either the Swiss or Sardinian reference populations, whereas the Finnish Saami clearly stood apart. The Finnish Saami are distinct from other Circumarctic populations, although two of the lineages found among the Saami showed closer relationship to the Circumarctic than to the European lineages. The sequence data indicated an exceptionally high divergence for the Saami mtDNA control lineages. The distribution of the pairwise nucleotide differences in the Saami suggested that this population has not experienced an expansion similar to what was indicated for the Finns and the reference populations.     

Molecular analysis of bacterial isolates and total community DNA from kraft pulp mill effluent treatment systems

Chloroaliphatics are major components of bleached kraft mill effluents. Gene probes and oligonucleotide primers were developed to monitor kraft pulp mill effluent treatment systems for the presence of key genes (dehalogenases) responsible for the dehalogenation of chloroaliphatic organics. The primers were used for polymerase chain reaction (PCR) analysis of genomic DNA extracted from dehalogenating bacterial isolates and from total community DNA extracted from water and sediments of mill effluent treatment system. PCR amplification with oligonucleotide primers designed from dhlB, encoding the haloacid dehalogenase from Xanthobacter autotrophicus, revealed the presence of dehalogenase genes in both aerated lagoons and stabilization basins. Similarly, positive results were obtained with mmoX primers designed from the soluble methane monooxygenase gene of Methylococcus capsulatus Bath. The haloacetate dehalogenase encoding gene (dehH2) from Moraxella sp. was typically not detected in mill effluent treatment systems unless the biomass was selectively enriched. DNA sequence analysis of several PCR fragaments revealed significant similarity to known dehalogenase amd methane monooxygenase genes. The results indicated a broad distribution of known dehalogenation genes and bacteria with chloroorganic-degrading potential in the mill effluent treatment systems.     

New karyotypes of two related species of Oligoryzomys genus (Cricetidae, Rodentia) involving centric fusion with loss of NORs and distribution of telomeric (TTAGGG)n sequences

Oral administration of ethyl O-[N-(p-carboxyphenyl-carbamoyl]-mycophenolate (CAM), a derivative of mycophenolic acid (MPA) and an inosine monophosphate dehydrogenase inhibitor, dose-dependently suppressed acute experimental allergic encephalomyelitis in Lewis rats without exerting any serious adverse effects. A daily dose of 50 mg/kg of CAM almost completely abolished both the clinical disease and the inflammation in the CNS. In the CAM-treated rats, a weight loss and fluctuations of peripheral lymphocyte subsets were minimized. The CAM treatment was effective when started at the time of sensitization but ineffective when deferred till day 10. Furthermore, CAM reduced the percentage of CD4+CD45RC- cells in the peripheral blood. The only detectable adverse effect was moderate anemia but it was rapidly improved after withdrawal of the drug. This drug could be a useful adjunct for the long-term immunosuppressive therapy for inflammatory diseases of the CNS.