Evidence for long‐term migration on the Balkan Peninsula using dental and cranial nonmetric data: Early interaction between Corinth (Greece) and its colony at Apollonia (Albania)

This article seeks to identify “Greeks” and “non‐Greeks” in “mixed” mortuary contexts in a Greek colony. Specifically, we test the hypothesis that Illyrian and Greek individuals lived and were buried together at the Corinthian colony of Apollonia, Albania (established ca. 600 BC). The pattern of human biological interaction at Apollonia is tested by identifying variation in genetic relatedness using biodistance analysis of dental and cranial nonmetric traits for three sites: Apollonia (n = 116), its founder‐city Corinth (n = 69), and Lofkënd (n = 108), an inland site near Apollonia pre‐dating colonization. Logistic regression analysis estimates that individuals from colonial Apollonia are most closely related to prehistoric Illyrian populations (from Lofkënd and prehistoric Apollonia), rather than Greeks (from Corinth). The phenotypic similarity between colonial Apollonia and prehistoric Illyria suggests that there was a large Illyrian contribution to the gene pool at the colony of Apollonia. However, some trait combinations show low biological distances among all groups, suggesting homogeneity among Illyrian and Greek populations (assessed through pseudo‐Mahalanobis' D²). The degree of phenotypic similarity suggests shared ancestry and long‐term migration throughout these regions. The impacts of missing data and small sample sizes are also considered. Am J Phys Anthropol 153:236–248, 2014. © 2013 Wiley Periodicals, Inc.     

Non‐native fruit trees facilitate colonization of native forest on abandoned farmland

Ecological restoration of abandoned, formerly forested farmland can improve the delivery of ecosystem services and benefit biodiversity conservation. Restoration programs can involve removing isolated, non‐native trees planted by farmers for fruit or wood. As such “legacy” trees can attract seed dispersers and create microclimates that help native seedlings to establish, removing them may actually slow forest recovery. Working on abandoned farmland in Kibale National Park, Uganda, we evaluated the effect of legacy trees on forest recovery by measuring the number, diversity, and biomass of native seedlings and saplings regenerating in plots centered on avocado (Persea americana), mango (Mangifera indica), and Eucalyptus legacy trees compared with adjacent plots without legacy trees. The assemblages of native, forest‐dependent tree species in plots around avocado and mango trees were distinct from each other and from those around eucalyptus and all the near‐legacy plots. In particular, avocado plots had higher stem density and species richness of forest‐dependent species than near‐avocado plots, particularly large‐seeded, shade‐tolerant, and animal‐dispersed species—key targets of many restoration plans. Furthermore, many of the species found in high numbers were among those failing to establish in ongoing large‐scale forest restoration in Kibale. Taken together, our results demonstrate that the legacy trees facilitate the dispersal and establishment of native tree species. Retaining the existing legacy trees for a number of years could usefully complement existing management strategies to restore more biodiverse native forest in degraded lands. However, careful monitoring is needed to ensure that the legacy trees do not themselves establish.     

Isozyme evidence regarding the origins of three allopolyploid species ofPolytrichastrum (Polytrichaceae, Bryophyta)

Electrophoretic data show thatPolytrichastrum pallidisetum, P. ohioense, andP. sexangulare are allopolyploids. They display fixed, heterozygous banding patterns at five to six of the 11 enzyme loci that we screened. In total, we sampled 304 populations representing three genera (Polytrichastrum, Polytrichum, andPogonatum) and 18 species in our examination of the allopolyploids and their putative haploid progenitors. There were no extant species that fit perfectly as a progenitor of any allopolyploid. BothP. pallidisetum andP. ohioense appear to have originated as intergeneric hybrids between one progenitor with aPolytrichastrum-type genome and another with aPolytrichum-type genome. The extant haploid species with the most similar genomes to the putative progenitors ofP. pallidisetum werePolytrichastrum appalachianum andPolytrichum commune, whereas forPolytrichastrum ohioense the species werePolytrichastrum formosum (orP. longisetum) andPolytrichum commune. Polytrichastrum sexangulare was genetically more similar to species ofPogonatum, as was one taxon that appears to be one of its progenitors,P. sexangulare var.vulcanicum ( =Polytrichum/Pogonatum sphaerothecium). The other progenitor also must have possessed alleles that are common in species ofPogonatum. The Polytrichaceae are a relatively ancient group of mosses, and the hybridizations that gave rise to these allopolyploids may have occurred long ago. It is likely that the genomes of the original progenitors have changed over time or that those progenitors are now extinct.     

Amplification and invasiveness of epithelial progenitors during gastric carcinogenesis in trefoil factor 1 knockout mice

Abstract. Objective: It is not known whether or not epithelial progenitors of the pyloric antrum are involved in gastric carcinogenesis. Normally, these progenitors give rise to two main cell lineages: pit and gland mucous cells. This study was designed to examine the changes that occur in pyloric antral mucous cell lineages and their progenitors during development of gastric adenoma and carcinoma in trefoil factor 1 (TFF1) knockout mice. Materials and methods: Pyloric antral mucosal tissues of TFF1 knockout mice at ages from 3 days to 17 months were processed for histochemical analysis using Ulex europaeus and Grifforia simplifolica lectins as markers for pit and gland mucous cells, respectively. The dividing epithelial progenitors were identified by using immunohistochemical and electron microscopy techniques. Results: TFF1 loss was associated with amplification of both mucus‐secreting pit and gland cells. Both lectins examined bound not only to mature mucous cells, but also to most of epithelial progenitors which gradually amplified with age and frequently were seen in mitosis. Analysis of 12‐ to 17‐month‐old TFF1‐deficient stomachs revealed occasional groups of poorly differentiated mucosal cells with features similar to those of epithelial progenitors (or stem cells), in the basal portion of the antral mucosa. These cells eventually invaded the muscularis mucosa while maintaining some capacity to differentiate. Conclusion: This study shows that the progenitors of pit and gland mucous cells contribute to gastric carcinogenesis in the pyloric antrum of TFF1 knockout mice, strongly supporting the concept of stem cell origin of cancer.     

MTOR controls genesis and autophagy of GABAergic interneurons during brain development

Interneuron progenitors in the ganglionic eminence of the ventral telencephalon generate most cortical interneurons during brain development. However, the regulatory mechanism of interneuron progenitors remains poorly understood. Here, we show that MTOR (mechanistic target of rapamycin [serine/threonine kinase]) regulates proliferation and macroautophagy/autophagy of interneuron progenitors in the developing ventral telencephalon. To investigate the role of MTOR in interneuron progenitors, we conditionally deleted the Mtor gene in mouse interneuron progenitors and their progeny by using Tg(mI56i-cre,EGFP)1Kc/Dlx5/6-Cre-IRES-EGFP and Nkx2–1-Cre drivers. We found that Mtor deletion markedly reduced the number of interneurons in the cerebral cortex. However, relative positioning of cortical interneurons was normal, suggesting that disruption of progenitor self-renewal caused the decreased number of cortical interneurons in the Mtor-deleted brain. Indeed, Mtor-deleted interneuron progenitors showed abnormal proliferation and cell cycle progression. Additionally, we detected a significant activation of autophagy in Mtor-deleted brain. Our findings suggest that MTOR plays a critical role in the regulation of cortical interneuron number and autophagy in the developing brain.     

Mapping neurogenesis onset in the optic tectum of Xenopus laevis

Neural progenitor cells have a central role in the development and evolution of the vertebrate brain. During early brain development, neural progenitors first expand their numbers through repeated proliferative divisions and then begin to exhibit neurogenic divisions. The transparent and experimentally accessible optic tectum of Xenopus laevis is an excellent model system for the study of the cell biology of neurogenesis, but the precise spatial and temporal relationship between proliferative and neurogenic progenitors has not been explored in this system. Here we construct a spatial map of proliferative and neurogenic divisions through lineage tracing of individual progenitors and their progeny. We find a clear spatial separation of proliferative and neurogenic progenitors along the anterior‐posterior axis of the optic tectum, with proliferative progenitors located more posteriorly and neurogenic progenitors located more anteriorly. Since individual progenitors are repositioned toward more anterior locations as they mature, this spatial separation likely reflects an increasing restriction in the proliferative potential of individual progenitors. We then examined whether the transition from proliferative to neurogenic behavior correlates with cellular properties that have previously been implicated in regulating neurogenesis onset. Our data reveal that the transition from proliferation to neurogenesis is associated with a small change in cleavage plane orientation and a more pronounced change in cell cycle kinetics in a manner reminiscent of observations from mammalian systems. Our findings highlight the potential to use the optic tectum of Xenopus laevis as an accessible system for the study of the cell biology of neurogenesis. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 76: 1328–1341, 2016     

Possible tobacco progenitors share long-tongued hawkmoths as pollen vectors

The putative ancestors of the allopolyploid hybrid Nicotiana tabacum have distinct flower features, apparently suited either for hawkmoth or bat pollination. This suggests that progenitors were reproductively isolated by mechanical and ethological barriers. However, the present data show that in natural populations pollen vectors could be shared by two of the possible progenitors. Pollen vectors of one of the possible male progenitors (N. otophora) were short- and long-tongued hawkmoths and a nectar-feeding bat, while those of the female ancestor (N. sylvestris) were only long-tongued hawkmoths. The latter are then the most likely vectors responsible for the presumed spontaneous hybridization. These data also suggest that interspecific pollen transfer occurred more likely in one direction.     

Plant species identity drives soil microbial community structures that persist under a following crop

Compared to monocultures, multi‐species swards have demonstrated numerous positive diversity effects on aboveground plant performance, such as yield, N concentration, and even legacy effects on a following crop. Whether such diversity effects are seen in the soil microbiome is currently unclear. In a field experiment, we analyzed the effect that three plant species (a grass, forb, and legume), and mixtures of these, had on soil fungal and bacterial community structures, as well as their associated legacy effects under a following crop, the grass Lolium multiflorum. We utilized six sward types, three monocultures (Lolium perenne, Cichorium intybus and Trifolium pratense), two bi‐species mixtures, and a mixture of the three species. Soil samples were taken from these swards in March (at the end of a three year conditioning phase) and in June, August, and September after L. multiflorum was established, that is, the legacy samplings. When present, the differing monocultures had a significant effect on various aspects of the fungal community: structure, OTU richness, the relative abundance of the phylum Glomeromycota, and indicator OTUs. The effect on bacterial community structure was not as strong. In the multi‐species swards, a blending of individual plant species monoculture effects (identity effect) was seen in (a) fungal and bacterial community structure and (b) fungal OTU richness and the relative abundance of the Glomeromycota. This would indicate that plant species identity, rather than diversity effects (i.e., the interactions among the plant species), was the stronger determinant. During the legacy samplings, structural patterns in the fungal and bacterial communities associated with the previous swards were retained, but the effect faded with time. These results highlight that plant species identity can be a strong driver of soil microbial community structures. They also suggest that their legacy effect on the soil microbiome may play a crucial role in following crop performance.     

Antibodies against pax6 immunostain amacrine and ganglion cells and neuronal progenitors,but not rod precursors,in the normal and regenerating retina of the goldfish

Pax6 is a developmental regulatory gene that plays a key role in the development of the embryonic brain, eye, and retina. This gene is also expressed in discrete groups of neurons within the adult brain. In this study, antibodies raised against a fusion protein from a zebra fish pax6 cDNA were used to investigate the expression of the pax6 gene in the mature, growing, and regenerating retina of the goldfish. On western blots of retinal proteins, the pax6 antibodies recognize a single band at the approximate size of the zebra fish pax6 protein. In retinal sections, the antibodies label the nuclei of mature amacrine and some ganglion cells. At the retinal margin, where neurogenesis and cellular differentiation continually occur in goldfish, the antibodies label neuronal progenitors and the newly postmitotic neurons. Following injury and during neuronal regeneration, the antibodies label mitotically active progenitors of regenerating neurons. Rod precursors, proliferating cells that normally give rise solely to rod photoreceptors and are the presumed antecedents of the injury-stimulated neuronal progenitors, are not immunostained by antibodies to the pax6 protein. The results of this study document the identity of pax6-expressing cells in the mature retina and demonstrate that in the goldfish pax6 is expressed in neuronal progenitors during both retinal growth and regeneration. © 1996 John Wiley & Sons, Inc.     

Legacy of thinning on woody species composition and structure in southern Appalachian Mountain hardwood forests: restoration implications

In the Appalachian Mountains, Liriodendron tulipifera monocultures are widespread, with these forests lacking both species and structural diversity. In this study, we developed models that described the effects of thinning treatments, conducted almost 60 years ago, on the density, composition, and functional identity of the woody understory in L. tulipifera forests. The woody understory of these thinned L. tulipifera forests was diverse, with the small seedling (<1.4 m), large seedling (≥1.4 m and <2.54 cm dbh), and sapling (≥2.54 and <12.7 cm) layers possessing 38, 32, and 23 species, respectively. Although model performance was low to moderate (r² = 0.05–0.40), we found that legacy effects, alone or in combination with environmental variables, explained, in part, the variability associated with the density, composition, and functional identity of the small seedling, large seedling, and sapling size classes, with the relative influence of legacy versus environmental effects varying by metric and size class. Post-thinning basal area and/or percent of basal area removed were not the primary legacy effects influencing the woody understory. Instead, legacy effects associated with species composition of the overstory before and/or after thinning along with average stem diameter post-thinning, variation in stem diameter post-thinning, and age at the time of thinning were more influential than density or thinning intensity. This study provides evidence that conserving species diversity during forest management activities can have positive long-term effects on composition and function of the woody understory and increase restoration potential.     

Genetic variation in Miscanthus × giganteus and the importance of estimating genetic distance thresholds for differentiating clones

Miscanthus × giganteus (Mxg) is an important bioenergy feedstock crop, however, genetic diversity among legacy cultivars may be severely constrained. Only one introduction from Japan to Denmark of this sterile, triploid, vegetatively propagated crop was recorded in the 1930s. We sought to determine if the Mxg cultivars in North America were all synonyms, and if they were derived from the European introduction. We used 64 nuclear and five chloroplast simple sequence repeat (SSR) markers to estimate genetic similarity for 27 Mxg accessions from North America, and compared them with six accessions from Europe, including the species’ type‐specimen. A subset of accessions was also evaluated by restriction‐site associated DNA sequencing (RAD‐seq). In addition, we assessed the potential of new crosses to increase Mxg genetic diversity by comparing eight new triploid Mxg progeny grown from seed, along with samples of the parental species M. sacchariflorus and M. sinensis. Estimates of genotyping error rates were essential for distinguishing between experimental error and true genotypic differences among accessions. Given differences in estimated error rates and costs per marker for SSRs and RAD‐seq, the former is currently more cost‐effective for determining if two accessions are genetically identical. We concluded that all of the Mxg legacy cultivars were derived via vegetative propagation from a single genet. In contrast with the Mxg legacy cultivars, genetic similarity to the type‐specimen of eight new triploid Mxg progeny ranged from 0.46 to 0.56. Though genetic diversity among the Mxg legacy cultivars is critically low, new crosses can provide much‐needed variation to growers.     

Transient oral microflora in Greeks attending day centres for the elderly and residents in homes for the elderly

Objective: To examine the isolation frequency and the carriage of yeasts, Enterobacteriaceae, Staphylococcus and Enterococcus species in oral samples from elderly Greeks living alone or in institutions. Background: Ageing may promote changes in the oral ecosystem, which lead to colonisation of the mouth by microbes found less commonly or only transiently in younger subjects. Previous studies indicate a geographical variation in the isolation frequency of such bacteria in elderly populations. Materials and methods: Medical and dental records were obtained from 66 attenders at elderly people's day centres (EPDC), and 82 residents of elderly people's homes (EPH), 66–95 years old. Mucosa smear samples were cultured on appropriate media for enumeration of the above species. Microbial identification was performed by conventional microbiological tests. The results were analysed using the Multiple Correspondence Analysis (MCA), anova and other traditional statistical tests. Results: No statistically significant association was found between the place of residence and the wearing of dentures. The isolation frequencies of Staphylococcus aureus, Enterococcus and Enterobacteriaceae species were 21.6, 20.3 and 7.4% respectively. MCA, and further statistical analysis, revealed that the place of residence affected the isolation frequency of years (54.9% in EPH vs. 37.9% in EPDC). Moreover, anova showed that living in EPH increased the carriage of yeasts. Conclusions: Elderly Greeks exhibit a moderate to high oral carriage of transient bacteria compared with other elderly populations. Living in EPH seems to increase both the isolation frequency and carriage of yeasts.     

FGF signaling gradient maintains symmetrical proliferative divisions of midbrain neuronal progenitors

For the correct development of the central nervous system, the balance between self-renewing and differentiating divisions of the neuronal progenitors must be tightly regulated. To maintain their self-renewing identity, the progenitors need to retain both apical and basal interfaces. However, the identities of fate-determining signals which cells receive via these connections, and the exact mechanism of their action, are poorly understood. The conditional inactivation of Fibroblast growth factor (FGF) receptors 1 and 2 in the embryonic mouse midbrain–hindbrain area results in premature neuronal differentiation. Here, we aim to elucidate the connection between FGF signaling and neuronal progenitor maintenance. Our results reveal that the loss of FGF signaling leads to downregulation of Hes1 and upregulation of Ngn2, Dll1, and p57 in the ventricular zone (VZ) cells, and that this increased neurogenesis occurs cell-autonomously. Yet the cell cycle progression, apico-basal-polarity, cell–cell connections, and the positioning of mitotic spindle in the mutant VZ appear unaltered. Interestingly, FGF8-protein is highly concentrated in the basal lamina. Thus, FGFs may act through basal processes of neuronal progenitors to maintain their progenitor status. Indeed, midbrain neuronal progenitors deprived in vitro of FGFs switched from symmetrical proliferative towards symmetrical neurogenic divisions. We suggest that FGF signaling in the midbrain VZ is cell-autonomously required for the maintenance of symmetrical proliferative divisions via Hes1-mediated repression of neurogenic genes.     

Plant community recovery following Sericea lespedeza (Lespedeza cuneata) removal: testing for a soil legacy effect

Restoration of plant communities can be hindered by the legacy of previously established invaders, despite their physical removal from the community. Current evidence, mainly built on short‐term greenhouse experiments, suggests that Sericea lespedeza (Lespedeza cuneata) invasion not only suppresses native plant species, but also alters soil conditions in host communities. As a result, L. cuneata may create a soil legacy that impedes plant community restoration. We examined the response of a Kansas grassland following L. cuneata removal to determine if historical L. cuneata abundance affected (1) plant community composition and (2) the establishment of additional native species. To address these questions, L. cuneata seeds were sown into 300 plots at a wide range of densities under different combinations of simulated disturbance and soil fertilization. After a three‐year establishment period, L. cuneata was removed from the community, and 13 native forb species were sown into all plots. Over 4 years, we found little evidence for a soil legacy effect that influenced community response post‐removal. Although there was a detectable relationship between community composition and L. cuneata, the variation explained by this relationship was very low. Similarly, the establishment of sown native species was unrelated to the historical abundance of L. cuneata. These results indicate that, regardless of initial density, L. cuneata does not impede plant community recovery in this system if effectively controlled within the first 3 years of invasion, and legacy effects inferred from greenhouse experiments may not translate to impacts on the plant community in the field.     

Cytogenetic and flow cytometry data expand knowledge of genome evolution in three <Emphasis Type="Italic">Coffea</Emphasis> species

Karyotype and nuclear 2C-value data are considered important in taxonomic and evolutionary approaches in Coffea. Still, new methods are needed to further support such studies, especially to determine the progenitors of Coffea arabica. In this work, new cytogenetic and flow cytometry data were used to compare Coffea arabica, Coffea canephora and Coffea congensis. These data corroborate the hypothesis that C. canephora and C. congensis originated from a single ancestor, whose basic chromosome number was x = 11. In agreement with the observations of other authors, the karyotype and mean 2C-values confirm that C. arabica is a true allotetraploid originating from two diploid Coffea species with similar genomes. Although C. canephora and C. congensis have been considered potential progenitors of C. arabica, karyotype comparison revealed that only one of these species may be parental to C. arabica. These accurate cytogenetic and flow cytometry data contribute to expand our knowledge of the Coffea genome, as well as of possible progenitors of C. arabica.     

Allotetraploids in Patagonia with Affinities to Western North American Diploids: Did Dispersal or Genome Doubling Occur First?

Amphitropical disjunct distributions between western North America and western South America have intrigued botanists for over a century. Here, specific examples of migration and speciation are investigated using herbaceous species from the phlox family (Polemoniaceae) as a model for considering the timing of dispersal relative to speciation. Comparative DNA sequencing reveals that, in Collomia and Navarretia, the South American species are allopolyploids, suggesting either two dispersals prior to the allopolyploidization event for each species with subsequent extirpation of the diploid progenitors from South America, or allopolyploid formation prior to dispersal with extirpation of these polyploids from North America. Divergence time estimates support a Pliestocene dispersal hypothesis and sequence data indicate that, at least in Collomia, hybridization of the diploid progenitors occurred in South America.     

Drought and its legacy modulate the post‐fire recovery of soil functionality and microbial community structure in a Mediterranean shrubland

The effects of drought on soil dynamics after fire are poorly known, particularly its long‐term (i.e., years) legacy effects once rainfall returns to normal. Understanding this is particularly important for nutrient‐poor soils in semi‐arid regions affected by fire, in which rainfall is projected to decrease with climate change. Here, we studied the effects of post‐fire drought and its legacy on soil microbial community structure and functionality in a Cistus‐Erica shrubland (Spain). Rainfall total and patterns were experimentally modified to produce an unburned control (natural rainfall) and four burned treatments: control (natural rainfall), historical control (long‐term average rainfall), moderate drought (percentile 8 historical rainfall, 5 months of drought per year), and severe drought (percentile 2, 7 months of drought). Soil nutrients and microbial community composition (ester‐linked fatty acid approach) and functionality (enzyme activities and C mineralization rate) were monitored during the first 4 years after fire under rainfall treatments, plus two additional ones without them (six post‐fire years). We found that the recovery of burned soils was lower under drought. Post‐fire drought increased nitrate in the short term and reduced available phosphorus, exchangeable potassium, soil organic matter, enzyme activities, and carbon mineralization rate. Moreover, drought decreased soil total microbial biomass and fungi, with bacteria becoming relatively more abundant. Two years after discontinuing the drought treatments, the drought legacy was significant for available phosphorus and enzyme activities. Although microbial biomass did not show any drought legacy effect, the proportion of fungi and bacteria (mainly gram‐positive) did, being lower and higher, respectively, in former drought‐treated plots. We show that drought has an important impact on soil processes, and that some of its effects persist for at least 2 years after the drought ended. Therefore, drought and its legacy effects can be important for modeling biogeochemical processes in burned soils under future climate change.