The study of genetic diversity patterns of Coffea commersoniana, an endangered coffee species from Madagascar: a model for conservation of other littoral forest species

Madagascar has 59 described species of Coffea, of which 42 are listed as critically endangered, endangered, or vulnerable by the criteria of the Red List Category system of the World Conservation Union (IUCN). The littoral forest of Madagascar is a distinctive type of humid evergreen forest restricted to unconsolidated sand located within a few kilometers of the Indian Ocean, now persisting only as small fragments with ca. 10 % of its original range remaining. In an attempt to understand the genetic diversity of Madagascan coffee species, we studied ex situ and in situ populations of Coffea commersoniana, an endemic species of the littoral forests of southeastern Madagascar and soon to be impacted by mining activities in that region. The in situ populations studied showed higher genetic diversity than the ex situ population. The genetic partitioning among the two in situ populations of C. commersoniana was high enough to necessitate keeping the two populations separate for restoration purposes. Based on these findings, recommendations for conservation management (in situ and ex situ) are made.     

Microevolutionary patterns and processes of the Native Hawaiian colonizing fern Odontosoria chinensis (Lindsaeaceae)

Abstract.— The vascular‐plant flora of the Hawaiian Islands is characterized by one of the highest rates of species endemism in the world. Among flowering plants, approximately 89% of species are endemic, and among pteridophytes, about 76% are endemic. At the single‐island level, however, rates of species endemism vary dramatically between these two groups with 80% of angiosperms and only 6% of pteridophytes being single‐island endemics. Thus, in many groups of Hawaiian angiosperms, it is possible to link studies of phylogeny, evolution, and biogeographic history at the interspecific and interisland levels. In contrast, the low level of single‐island species endemism among Hawaiian pteridophytes makes similar interspecific and interisland studies nearly impossible. Higher levels of interisland gene flow may account for the different levels of single‐island endemism in Hawaiian pteridophytes relative to angiosperms. The primary question we addressed in the present study was: Can we infer microevolutionary patterns and processes among populations within widespread species of Hawaiian pteridophytes wherein gene flow is probably common? To address this broad question, we conducted a population genetic study of the native Hawaiian colonizing species Odontosoria chinensis. Data from allozyme analyses allowed us to infer: (1) significant genetic differentiation among populations from different islands; (2) historical patterns of dispersal between particular pairs of islands; (3) archipelago‐level patterns of dispersal and colonization; (4) founder effects among populations on the youngest island of Hawaii; and, (5) that this species primarily reproduces via outcrossing, but may possess a mixed‐mating system.     

Kinetochores: NDC80 toes the line

Kinetochore-associated NDC80 complexes serve as the primary binding site for the plus-ends of spindle microtubules in mitosis. A recent study proposes a novel mechanism for regulating kinetochore-microtubule binding involving NDC80 complex oligomerization, which could be mediated by Aurora B kinase.     

In vitro and in vivo evaluation of 6-aminopyrazolyl-pyridine-3-carbonitriles as JAK2 kinase inhibitors

Synthesis and biological evaluation of a series of 6-aminopyrazolyl-pyridine-3-carbonitriles as JAK2 kinase inhibitors was reported. Biochemical screening, followed by profile optimization, resulted in JAK2 inhibitors exhibiting good kinase selectivity, pharmacokinetic properties, physical properties and pharmacodynamic effects.     

Recruitment of the human Cdt1 replication licensing protein by the loop domain of Hec1 is required for stable kinetochore-microtubule attachment

Cdt1, a protein critical for replication origin licensing in G1 phase, is degraded during S phase but re-accumulates in G2 phase. We now demonstrate that human Cdt1 has a separable essential mitotic function. Cdt1 localizes to kinetochores during mitosis through interaction with the Hec1 component of the Ndc80 complex. G2-specific depletion of Cdt1 arrests cells in late prometaphase owing to abnormally unstable kinetochore-microtubule (kMT) attachments and Mad1-dependent spindle-assembly-checkpoint activity. Cdt1 binds a unique loop extending from the rod domain of Hec1 that we show is also required for kMT attachment. Mutation of the loop domain prevents Cdt1 kinetochore localization and arrests cells in prometaphase. Super-resolution fluorescence microscopy indicates that Cdt1 binding to the Hec1 loop domain promotes a microtubule-dependent conformational change in the Ndc80 complex in vivo. These results support the conclusion that Cdt1 binding to Hec1 is essential for an extended Ndc80 configuration and stable kMT attachment.     

Chloroplast DNA variation in a wild plant, tolmiea menziesii

Few studies of cpDNA have provided evolutionary and/or phylogenetic information at the intraspecific level. We analyzed restriction site variation using 19 endonucleases in 37 populations representing both diploid (2n = 14) and autotetraploid (2n = 28) Tolmiea menziesii. Seven restriction site mutations and five length mutations were observed. Although diploid and tetraploid Tolmiea have been intensively studied using nuclear markers, cpDNA variation provided additional evolutionary insights not revealed previously. The chloroplast genomes of diploid and tetraploid Tolmiea are as distinct as those of many pairs of congeneric species of angiosperms. Based on outgroup comparisons, the primitive chloroplast genome is present in tetraploid rather than diploid Tolmiea. These findings suggest that either: (1) diploid and tetraploid Tolmiea may have diverged since the origin of the autotetraploid, (2) the original diploid donor of the cytoplasm present in the tetraploid subsequently became extinct, or (3) the diploid was actually derived from the tetraploid via polyhaploidy. cpDNA variation also revealed that despite their close geographic proximity, diploid and tetraploid Tolmiea do not experience cytoplasmic gene flow. Last, three cytoplasmically distinct groups of diploid populations exist, two of which occupy distinct geographic areas. These findings demonstrate that, at least in some plant species, restriction fragment analysis of cpDNA can provide important evolutionary and phylogenetic information at low taxonomic levels.     

Dopamine D1 receptor activation of adenylyl cyclase, not phospholipase C, in the nucleus accumbens promotes maternal behavior onset in rats

A body of evidence supports the idea that the mesolimbic dopamine (DA) system modulates the natural increase in responsiveness female rats show toward offspring (biological or foster) at birth. In the absence of the full hormonal changes associated with pregnancy and birth, female rats do not show immediate responsiveness toward foster offspring. Activation of the mesolimbic DA system can produce an immediate onset of maternal behavior in these females. For example, female rats that are hysterectomized and ovariectomized on day 15 of pregnancy (15HO) and presented with pups 48 hours later normally show maternal behavior after 2-3 days of pup exposure, but will show maternal behavior on day 0 of testing after microinjection of the DA D₁ receptor agonist, SKF 38393, into the nucleus accumbens (NA) at the time of pup presentation. DA D₁ receptor stimulation is known to activate cAMP intracellular signaling cascades via its stimulation of adenylyl cyclase (AC). However, some DA D₁ receptors are also linked to phospholipase C (PLC) and are capable of activating phosphatidylinositol signaling cascades. SKF 38393 stimulates both types of D₁ receptors. Here we provide evidence that the facilitatory effects of DA D₁ receptor stimulation in the NA on maternal behavior are mediated by AC-linked DA D₁ receptors. By examining the effects of intra-NA application of SKF 83822, a drug which selectively binds DA D₁-AC receptors, or SKF 83959, a drug which selectively activates D₁-PLC-linked receptors, we find that only SKF 83822 facilitates maternal behavior onset.     

Patterns of Clonal Diversity in Dicranopteris linearis on Mauna Loa,Hawaii1

The clonal mat-forming fern, Dicranopteris linearis (N. L. Burm.) Underw., dominates vast areas of rainforests on the windward slopes of Mauna Loa Volcano on the island of Hawai'i. Because clone size has important ecological and evolutionary consequences in such a dominant species, we used isozyme analysis to investigate clone size and other aspects of genetic diversity and reproduction over a broad range of environmental conditions on primary successional sites (pahoehoe lava substrates). Isozyme analysis provided a measure of the upper limit of clonal size in this interdigitating clonal species. Each 0.5-ha primary successional site on Mauna Loa was comprised of a minimum of two to four clones. Genetic diversity in Dicranopteris was low; of 32 putative loci investigated, only 4 were polymorphic, with 2 or 3 alleles/locus. Over the 17 study locations on Mauna Loa and Kilauea Volcanoes, we identified nine multilocus genotypes based on unique combinations of allozymes. Seven of the nine genotypes were heterozygous for at least one locus, evidence of an intergametophytic mating system. Highly dispersible spores, coupled with intergametophytic mating should promote higher genetic diversity. We propose that the following factors contributed to low genetic diversity: founder effects; extreme isolation from mainland gene pools; high potential for mating among different gametophytes produced from the same sporophyte; relatively low numbers of safe sites for gametophyte establishment over space and time; and long-term reliance on vegetative growth. Leaf phenotypes were associated with genotype, but also with environmental conditions. Enough variability within a genotype existed to support the current treatment of Hawaiian Dicranopteris as one species. Vegetative growth was the primary means by which Dicranopteris covered the landscape. Nevertheless, spore production, gametophyte establishment, and sexual reproduction were absolutely essential for colonization of the few favorable microsites available on pahoehoe lava substrates of Mauna Loa following lava eruptions, dieback, and similar landscape-level disturbances.