Search

From 1957 to 1962, thalidomide caused birth defects in >10,000 children. While the drug was pulled from the market, thalidomide is currently prescribed to treat conditions including leprosy. As a result, a new generation of babies with thalidomide defects is being born in the developing world. This represents a serious problem, as the mechanisms by which thalidomide disrupts development remain unresolved. This lack of resolution is due, in part, to the absence of an appropriate mammalian model for thalidomide teratogenesis. We test the hypothesis that opossum (Monodelphis domestica) is well suited to model human thalidomide defects. Results suggest that opossum embryos exposed to thalidomide display a range of phenotypes (e.g., heart, craniofacial, limb defects) and penetrance similar to humans. Furthermore, all opossums with thalidomide defects exhibit vascular disruptions. Results therefore support the hypotheses that opossums make a good mammalian model for thalidomide teratogenesis, and that thalidomide can severely disrupt angiogenesis in mammals.

There are numerous records of conjoined twinning in humans and domesticated animals, but many fewer for wild animals because of the early death of conjoined twins. We here describe the incidental discovery and skeletal anatomy of a wild-caught bat fetus with two heads. To our knowledge, this is only the second conjoined bat fetus described, and the first conjoined Artibeus phaeotis. We also revisit the anatomy of the first conjoined bat that was described, a stillborn Eptesicus fuscus.

Background Retinoic acid (RA) is a vitamin A derivative. Exposure to exogenous RA generates congenital limb malformations (CLMs) in species from frogs to humans. These CLMs include but are not limited to oligodactyly and long-bone hypoplasia. The processes by which exogenous RA induces CLMs in mammals have been best studied in mouse, but as of yet remain unresolved. Methods We investigated the impact of exogenous RA on the cellular and molecular development of the limbs of a nonrodent model mammal, the opossum Monodelphis domestica. Opossums exposed to exogenous retinoic acid display CLMs including oligodactly, and results are consistent with opossum development being more susceptible to RA-induced disruptions than mouse development. Results Exposure of developing opossums to exogenous RA leads to an increase in cell death in the limb mesenchyme that is most pronounced in the zone of polarizing activity, and a reduction in cell proliferation throughout the limb mesenchyme. Exogenous RA also disrupts the expression of Shh in the zone of polarizing activity, and Fgf8 in the apical ectodermal ridge, and other genes with roles in the regulation of limb development and cell death. Conclusion Results are consistent with RA inducing CLMs in opossum limbs by disrupting the functions of the apical ectodermal ridge and zone of polarizing activity, and driving an increase in cell death and reduction of cell proliferation in the mesenchyme of the developing limb. Birth Defects Research (Part A) 103:225–234, 2015. © 2015 Wiley Periodicals, Inc.

Background From bat wings to whale flippers, limb diversification has been crucial to the evolutionary success of mammals. We performed the first transcriptome-wide study of limb development in multiple species to explore the hypothesis that mammalian limb diversification has proceeded through the differential expression of conserved shared genes, rather than by major changes to limb patterning. Specifically, we investigated the manner in which the expression of shared genes has evolved within and among mammalian species. Results We assembled and compared transcriptomes of bat, mouse, opossum, and pig fore- and hind limbs at the ridge, bud, and paddle stages of development. Results suggest that gene expression patterns exhibit larger variation among species during later than earlier stages of limb development, while within species results are more mixed. Consistent with the former, results also suggest that genes expressed at later developmental stages tend to have a younger evolutionary age than genes expressed at earlier stages. A suite of key limb-patterning genes was identified as being differentially expressed among the homologous limbs of all species. However, only a small subset of shared genes is differentially expressed in the fore- and hind limbs of all examined species. Similarly, a small subset of shared genes is differentially expressed within the fore- and hind limb of a single species and among the forelimbs of different species. Conclusions Taken together, results of this study do not support the existence of a phylotypic period of limb development ending at chondrogenesis, but do support the hypothesis that the hierarchical nature of development translates into increasing variation among species as development progresses. Electronic supplementary material The online version of this article (doi:10.1186/s12862-017-0902-6) contains supplementary material, which is available to authorized users.

A reduction in the number of digits has evolved many times in tetrapods, particularly in cursorial mammals that travel over deserts and plains, yet the underlying developmental mechanisms have remained elusive. Here we show that digit loss can occur both during early limb patterning and at later post-patterning stages of chondrogenesis. In the 'odd-toed' jerboa (Dipus sagitta) and horse and the 'even-toed' camel, extensive cell death sculpts the tissue around the remaining toes. In contrast, digit loss in the pig is orchestrated by earlier limb patterning mechanisms including downregulation of Ptch1 expression but no increase in cell death. Together these data demonstrate remarkable plasticity in the mechanisms of vertebrate limb evolution and shed light on the complexity of morphological convergence, particularly within the artiodactyl lineage.

RESUMO Apresentamos listagem da entomofauna visitante de flores do estado de Mato Grosso do Sul (MS) com base na compilação de informações obtidas em 17 estudos, a maioria realizado em áreas de Cerrado (n = 11) e menos frequentemente no Pantanal (n = 6). Foram registrados 10 grupos de insetos, pertencentes a seis ordens, 80 famílias e 411 espécies. Maior riqueza foi amostrada para o Cerrado (307 spp.) que Pantanal (147 spp.), com somente 43 espécies (10,4%) em comum entre estes biomas. Anthophila foi o grupo mais rico (155 spp.), seguido por besouros (82), borboletas/mariposas (53) e vespas (45), que junto totalizaram 81,5% das espécies. Maior riqueza de abelhas está relacionada ao fato da maioria dos trabalhos enfocarem este grupo, além da especialização deste grupo na utilização de recursos florais. Surpreendente foi o segundo lugar ocupado por besouros em relação a outros visitantes mais “ativos” e “habituais”, como lepidópteros e moscas. Em MS os acervos e grupos de pesquisa com entomofauna antófila são restritos e/ou incipientes, sendo necessário fortalecimento dos mesmos através de parcerias, intercâmbios e formação de recursos humanos na área. ABSTRACT We present a checklist of the anthophilous entomofauna of Mato Grosso do Sul state (MS) based on information compiled from 17 studies, most of them achieved in Cerrado vegetation (n = 11) and less frequently in the Pantanal (n = 6). We recorded 10 groups of insects, belonging to six orders, 80 families and 411 species. Higher richness was sampled for Cerrado (307 spp.) compared to Pantanal (147 spp.), with only 43 species (10.4%) common to both biomes. Anthophila was the richest group (155 spp.), followed by beetles (82), butterflies/moths (53) and wasps (45), which totalized 81.5% of species. The highest richness of bees is related to the fact the most studies are concentrated in this group, besides the specialization of this group in utilization of floral resources. Surprising was the beetles occupying second place compared to others more “active” and “habitual” visitors, such as butterflies and flies. The entomofauna collections and research teams in MS are limited and/or incipient and they should be strenghtened through partnerships, exchange and capacity building in this biological group.

Deterioration of the intervertebral discs is an unfortunate consequence of aging. The intervertebral disc in mammals is composed of three parts: a jelly-like center called the nucleus pulposus, the cartilaginous annulus fibrosus and anterior and posterior endplates that attach the discs to vertebrae. In order to understand the origin of the disc, we have investigated the intervertebral region of chickens. Surprisingly, our comparison of mouse and chicken discs revealed that chicken discs lack nuclei pulposi. In addition, the notochord, which in mice forms nuclei pulposi, was found to persist as a rod-like structure and express Shh throughout chicken embryogenesis. Our fate mapping data indicates that cells originating from the rostral half of each somite are responsible for forming the avian disc while cells in the caudal region of each somite form vertebrae. A histological analysis of mammalian and non-mammalian organisms suggests that nuclei pulposi are only present in mammals.

A fundamental question in biology is “how is growth differentially regulated during development to produce organs of particular sizes?” We used a new model system for the study of differential organ growth, the limbs of the opossum (Monodelphis domestica), to investigate the cellular and molecular basis of differential organ growth in mammals. Opossum forelimbs grow much faster than hindlimbs, making opossum limbs an exceptional system with which to study differential growth. We first used the great differences in opossum forelimb and hindlimb growth to identify cellular processes and molecular signals that underlie differential limb growth. We then used organ culture and pharmacological addition of FGF ligands and inhibitors to test the role of the Fgf/Mitogen-activated protein kinases (MAPK) signaling pathway in driving these cellular processes. We found that molecular signals from within the limb drive differences in cell proliferation that contribute to the differential growth of the forelimb and hindlimbs of opossums. We also found that alterations in the Fgf/MAPK pathway can generate differences in cell proliferation that mirror those observed between wild-type forelimb and hindlimbs of opossums and that manipulation of Fgf/MAPK signaling affects downstream focal adhesion-extracellular matrix (FA-ECM) and Wnt signaling in opossum limbs. Taken together, these findings suggest that evolutionary changes in the Fgf/MAPK pathway could help drive the observed differences in cell behaviors and growth in opossum forelimb and hindlimbs.

Variation among individuals is a prerequisite of evolution by natural selection. As such, identifying the origins of variation is a fundamental goal of biology. We investigated the link between gene interactions and variation in gene expression among individuals and species using the mammalian limb as a model system. We first built interaction networks for key genes regulating early (outgrowth; E9.5–11) and late (expansion and elongation; E11-13) limb development in mouse. This resulted in an Early (ESN) and Late (LSN) Stage Network. Computational perturbations of these networks suggest that the ESN is more robust. We then quantified levels of the same key genes among mouse individuals and found that they vary less at earlier limb stages and that variation in gene expression is heritable. Finally, we quantified variation in gene expression levels among four mammals with divergent limbs (bat, opossum, mouse and pig) and found that levels vary less among species at earlier limb stages. We also found that variation in gene expression levels among individuals and species are correlated for earlier and later limb development. In conclusion, results are consistent with the robustness of the ESN buffering among-individual variation in gene expression levels early in mammalian limb development, and constraining the evolution of early limb development among mammalian species., Author Summary The variation generating mechanisms of development interact with the variation sorting mechanism of natural selection to produce organismal diversity. While the impacts of natural selection on existing variation have received much study, those of development on the generation of this variation remain less understood. This fundamental gap in our knowledge restricts our understanding of the key processes shaping evolution. In this study, we combine mathematical modeling, and population-level and cross-species assays of gene expression to investigate the relationship between the structure of the gene interactions regulating limb development and variation in the expression of limb genes among individuals and species. Results suggest that the way in which genes interact (i.e., development) biases the distribution of variation in gene expression among individuals, and that this in turn biases the distribution of variation among species.

The intervertebral disc (IVD) functions in the support and movement of the vertebrate body. It is composed of the collagenous annulus fibrosis (AF), which surrounds the inner nucleus pulposus (NP)....

This communication details the synthesis, biological activity, and binding mode of a novel class of 2-benzimidazole substituted pyrimidines. The most potent analogs disclosed showed low nanomolar activity for the inhibition of Lck kinase and a representative analog was co-crystallized with Hck (a structurally related member of the Src family kinases).

A new class of lymphocyte specific tyrosine kinase (lck) inhibitors based on an N-4,6-pyrimidine-N-alkyl-N′-phenyl urea scaffold is described. Many of these compounds showed low-nanomolar inhibition of lck kinase activity as well as IL-2 synthesis from Jurkat cells. One of these analogs, 7i, was shown to be orally efficacious by in vivo testing in a rat adjuvant-induced arthritis study.

Cyclization of various bisacylated hydrazines and pyrazolidines using DBU or sodium hydride leads to the formation of various mono-, bi- and tricyclic pyrazolone scaffolds in 41–98% yield. The convergent nature by which the precyclization intermediates are constructed allows for rapid derivatization about the pyrazolone core.

Retinoic acid (RA) is a vitamin A derivative. Exposure to exogenous RA generates congenital limb malformations (CLMs) in species from frogs to humans. These CLMs include but are not limited to oligodactyly and long-bone hypoplasia. The processes by which exogenous RA induces CLMs in mammals have been best studied in mouse, but as of yet remain unresolved.We investigated the impact of exogenous RA on the cellular and molecular development of the limbs of a nonrodent model mammal, the opossum Monodelphis domestica. Opossums exposed to exogenous retinoic acid display CLMs including oligodactly, and results are consistent with opossum development being more susceptible to RA-induced disruptions than mouse development.Exposure of developing opossums to exogenous RA leads to an increase in cell death in the limb mesenchyme that is most pronounced in the zone of polarizing activity, and a reduction in cell proliferation throughout the limb mesenchyme. Exogenous RA also disrupts the expression of Shh in the zone of polarizing activity, and Fgf8 in the apical ectodermal ridge, and other genes with roles in the regulation of limb development and cell death.Results are consistent with RA inducing CLMs in opossum limbs by disrupting the functions of the apical ectodermal ridge and zone of polarizing activity, and driving an increase in cell death and reduction of cell proliferation in the mesenchyme of the developing limb.

Since the origin of tetrapod limbs about 450 million years ago, every Class of land vertebrate - reptiles, birds, amphibians, and mammals - has undergone some degree of digit loss from the ancestral count of five. Even within mammals many species have independently reduced the number of digits as a locomotor adaptation. The repeated convergence on digit loss indicates it is perhaps mechanistically simple, yet little is known of the mechanisms or whether developmental constraints ensure the same mechanisms are re-deployed in divergent species. Here we show in the three-toed jerboa, horse, camel, and pig that the mechanisms of digit loss are varied and yet utilize recurring themes. Common characteristics of digit loss include downregulated expression of the growth factor fgf8 in the apical ectodermal ridge in the anterior and posterior limb of all species with reduced digits. We also see massively upregulated cell death in tissue that fails to become digits in the jerboa, horse, and camel. In the three-toed...

The transition of the mouse embryonic notochord into nuclei pulposi was determined ("fate mapped") in vivo in growth and differentiating factor-5 (GDF-5)-null mice using the Shhcre and R26R alleles.To determine whether abnormal nuclei pulposi formation from the embryonic notochord was responsible for defects present in adult nuclei pulposi of Gdf-5-null mice.The development, maintenance, and degeneration of the intervertebral disc are not understood. Previously, we demonstrated that all cells in the adult nucleus pulposus of normal mice are derived from the embryonic notochord. Gdf-5-null mice have been reported to contain intervertebral discs in which the nucleus pulposus is abnormal. It is currently unclear if disc defects in Gdf-5-null mice arise during the formation of nuclei pulposi from the notochord during embryogenesis or result from progressive postnatal degeneration of nuclei pulposi.Gdf-5 messenger RNA expression was examined in the discs of wild-type embryos by RNA in situ hybridization to determine when and where this gene was expressed. To examine nucleus pulposus formation in Gdf-5-null mice, intervertebral discs in which embryonic notochord cells were marked were analyzed in newborn and 24-week-old mice.Our Gdf-5 messenger RNA in situ experiments determined that this gene is localized to the annulus fibrosus and not the nucleus pulposus in mouse embryos. Notochord fate-mapping experiments revealed that notochord cells in Gdf-5-null mice correctly form nuclei pulposi.Our data suggest that the defects reported in the nucleus pulposus of adult Gdf-5-null mice do not result from abnormal patterning of the embryonic notochord. The use of mouse alleles to mark cells that produce all cell types that reside in the adult nucleus pulposus will allow for a detailed examination of disc formation in other mouse mutants that have been reported to contain disc defects.

The Mexican axolotl, Ambystoma mexicanum, has been a useful animal model to study heart development and cardiac myofibrillogenesis. A naturally-occurring recessive mutant, gene "c", for cardiac non-function in the Mexican axolotl causes a failure of myofibrillogenesis due to a lack of tropomyosin expression in homozygous mutant (c/c) embryonic hearts. Myofibril-inducing RNA (MIR) rescues mutant hearts in vitro by promoting tropomyosin expression and myofibril formation thereafter. We have studied the effect of MIR on the expression of various isoforms of cardiac troponin T (cTnT), a component of the thin filament that binds with tropomyosin. Four alternatively spliced cTnT isoforms have been characterized from developing axolotl heart. The expression of various cTnT isoforms in normal, mutant, and mutant hearts corrected with MIR, is evaluated by real-time RT-PCR using isoform specific primer pairs; MIR affects the total transcription as well as the splicing of the cTnT in axolotl heart.

A new class of bicyclic pyrrolopyrimidine-based Janus kinase 3 (JAK-3) inhibitors are described. Many of these inhibitors showed low nanomolar activity against JAK-3.

This communication details the synthesis, biological activity, and proposed binding mode of a novel class of tri-cyclic derivatives of 1,2-dihydro-pyrimido[4,5-c]pyridazines 1 and 2. The most potent analogs disclosed showed low nanomolar activity for the inhibition of Lck kinase.

A new class of tumor necrosis factor alpha (TNF-alpha) synthesis inhibitors based on an N-2,4-pyrimidine-N-phenyl-N'-phenyl urea scaffold is described. Many of these compounds showed low-nanomolar activity against lipopolysaccharide stimulated TNF-alpha production. X-ray co-crystallization studies with mutated p38alpha showed that these trisubstituted ureas interact with the ATP-binding pocket in a pseudo-bicyclic conformation brought about by the presence of an intramolecular hydrogen bonding interaction.

Introduction: Chordoma is a rare malignancy arising in the axial skeleton from notochord remnants. The T-box transcription factor, Brachyury (T), is associated with familial chordoma, is expressed in over 90% of chordomas, and is a driver of cell growth in cultured chordoma cells. Suppression of T expression or function in vitro results in down-regulation of cell growth pathways and reduction in matrix formation. To further understand the mechanisms of T's oncogenic properties, we sought to generate a murine model of constitutive, notochord-directed T expression. Methods: To produce elevated expression of T in the notochord-derived (ND) cells, we generated a murine transgenic animal in which a cassette (T/GFP) containing the β-actin promoter, a transcriptional stop sequence flanked by LoxP sites (FS), the murine T cDNA, an intragenic ribosomal entry sequence and a GFP cDNA was homologously recombined into the ROSA26 locus. We termed these animals FS-T/GFP mice. FS-T/GFP mice were mated to mice with Cre expression regulated by the developmentally-timed and tissue-specific control of the Sonic Hedgehog promoter (Shh-Cre mice). Results: Excision of the FS sequence by Cre was confirmed to result in constitutive expression of T and GFP in 293 cells prior to transgenic creation, and subsequently in cultured fibroblasts from ear punches of the transgenic animals. Mice containing homozygous FS-T/GFP at ROSA26 were healthy with no apparent physiologic or developmental defects and with the expected Mendelian ratios of sex and genotype. A cross of FS-T/GFP with Shh-Cre mice resulted in T/Cre pups that died perinatally with grossly evident heart, lung and kidney defects. In addition, these animals showed incomplete fusion of the vertebral bodies, and dysmorphic spinal disks. Elevated T protein levels and GFP co-expression in disk cells was demonstrated by immunofluorescent detection in tissue sections. Summary: Constitutive expression of T in ND lineage cells results in alteration of the morphology of intervertebral disks possibly indicative of a proliferative effect of Brachyury on ND cells. Expression of T in “off-target” tissues that express Sonic Hedgehog likely results in perinatal death. Citation Format: David A. Alcorta, Jennifer A. Maier, Brian D. Harfe, Michael J. Kelley. Murine model of chordoma: Sonic Hedgehog promoter-driven Cre activation of Brachyury (T) expression induces spinal disk abnormalities and perinatal lethal developmental defects. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 352. doi:10.1158/1538-7445.AM2013-352 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

This paper details the synthesis of a novel class of 1,2-dihydro-pyrimido[4,5-c]pyridazines and substituted 1,2-dihydro-3a,7,9,9b-tetraaza-cyclopenta[a]naphthalen-3-one. The most potent analogs disclosed showed low nanomolar activity for the inhibition of lck kinase.

If you've never spent much time around computers and the thought of shopping for one panics you, take heart. Finding the right personal computer for you has very little to do with the intimidating sight of sleek machinery, glowing video monitors, and salespeople who begin their pitches with ROM, RAM, and Ks. It has everything to do with simple English and a good look at your own needs.