Constraints and selection: insights from microsporogenesis in Asparagales

Developmental constraints have been proposed to interfere with natural selection in limiting the available set of potential adaptations. Whereas this concept has long been debated on theoretical grounds, it has been investigated empirically only in a few studies. In this article, we evaluate the importance of developmental constraints during microsporogenesis (male meiosis in plants), with an emphasis on phylogenetic patterns in Asparagales. Different developmental constraints were tested by character reshuffling or by simulated distributions. Among the different characteristics of microsporogenesis, only cell wall formation appeared as constrained. We show that constraints may also result from biases in the correlated occurrence of developmental steps (e.g., lack of successive cytokinesis when wall formation is centripetal). We document such biases and their potential outcomes, notably the establishment of intermediate stages, which allow development to bypass such constraints. These insights are discussed with regard to potential selection on pollen morphology.     

Endoscopic optical coherence tomography angiography using a forward imaging piezo scanner probe

A forward imaging endoscope for optical coherence tomography angiography (OCTA) featuring a piezoelectric fiber scanner is presented. Imaging is performed with an optical coherence tomography (OCT) system incorporating an akinetic light source with a center wavelength of 1300 nm, bandwidth of 90 nm and A‐line rate of 173 kHz. The endoscope operates in contact mode to avoid motion artifacts, in particular, beneficial for OCTA measurements, and achieves a transversal resolution of 12 μm in air at a rigid probe size of 4 mm in diameter and 11.3 mm in length. A spiral scan pattern is generated at a scanning frequency of 360 Hz to sample a maximum field of view of 1.3 mm. OCT images of a human finger as well as visualization of microvasculature of the human palm are presented both in two and three dimensions. The combination of morphological tissue contrast with qualitative dynamic blood flow information within this endoscopic imaging approach potentially enables improved early diagnostic capabilities of internal organs for diseases such as bladder cancer.      

Nicotinamide Impairs Entry into and Exit from Meiosis I in Mouse Oocytes

Following exit from meiosis I, mammalian oocytes immediately enter meiosis II without an intervening interphase, accompanied by rapid reassembly of a bipolar spindle that maintains condensed chromosomes in a metaphase configuration (metaphase II arrest). Here we study the effect of nicotinamide (NAM), a non-competitive pan-sirtuin inhibitor, during meiotic maturation in mouse oocytes. Sirtuins are a family of seven NAD⁺-dependent deacetylases (Sirt1-7), which are involved in multiple cellular processes and are emerging as important regulators in oocytes and embryos. We found that NAM significantly delayed entry into meiosis I associated with delayed accumulation of the Cdk1 co-activator, cyclin B1. GVBD was also inhibited by the Sirt2-specific inhibitor, AGK2, and in a very similar pattern to NAM, supporting the notion that as in somatic cells, NAM inhibits sirtuins in oocytes. NAM did not affect subsequent spindle assembly, chromosome alignment or the timing of first polar body extrusion (PBE). Unexpectedly, however, in the majority of oocytes with a polar body, chromatin was decondensed and a nuclear structure was present. An identical phenotype was observed when flavopiridol was used to induce Cdk1 inactivation during late meiosis I prior to PBE, but not if Cdk1 was inactivated after PBE when metaphase II arrest was already established, altogether indicating that NAM impaired establishment rather than maintenance of metaphase II arrest. During meiosis I exit in NAM-treated medium, we found that cyclin B1 levels were lower and inhibitory Cdk1 phosphorylation was increased compared with controls. Although activation of the anaphase-promoting complex-Cdc20 (APC-Cdc20) occurred on-time in NAM-treated oocytes, Cdc20 levels were higher in very late meiosis I, pointing to exaggerated APC-Cdc20-mediated proteolysis as a reason for lower cyclin B1 levels. Collectively, therefore, our data indicate that by disrupting Cdk1 regulation, NAM impairs entry into meiosis I and the establishment of metaphase II arrest.     

Paget disease of bone: mapping of two loci at 5q35-qter and 5q31

Paget disease of bone is characterized by focal increases of the bone-remodeling process. It is the second most common metabolic bone disease after osteoporosis. Genetic factors play a major role in the etiology of Paget disease of bone, and two loci have been mapped for the disorder: PDB1 and PDB2. The gene(s) causing the typical form of the disorder remains to be characterized. To decipher the molecular basis of Paget disease of bone, we performed genetic linkage analysis in 24 large French Canadian families (479 individuals) in which the disorder was segregating as an autosomal dominant trait. After exclusion of PDB2, a genomewide scan was performed on the three most informative family nuclei. LOD scores >1.0 were observed at seven locations. The 24 families were then used to detect strong evidence for linkage to chromosome 5q35-qter. Under heterogeneity, a maximum LOD score of 8.58 was obtained at D5S2073, at straight theta= .1. The same characteristic haplotype was carried by all patients in eight families, suggesting a founder effect. A recombination event in a key family confined the disease region within a 6-cM interval between D5S469 and the telomere. The 16 other families, with very low conditional probability of linkage to 5q35-qter, were further used, to map a second locus at 5q31. Under heterogeneity, a maximum LOD score of 3.70 was detected at D5S500 with straight theta=.00. Recombination events refined the 5q31 region within 12.2 cM, between D5S642 and D5S1972. These observations demonstrate the mapping of two novel loci for Paget disease of bone and provide further evidence for genetic heterogeneity of this highly prevalent disorder. It is proposed that the 5q35-qter and 5q31 loci be named "PDB3" and "PDB4," respectively.     

Human hormone-sensitive lipase (HSL): expression in white fat corrects the white adipose phenotype of HSL-deficient mice

In white adipose tissue (WAT), hormone-sensitive lipase (HSL) can mediate lipolysis, a central pathway in obesity and diabetes. Gene-targeted HSL-deficient (HSL-/-) mice with no detectable HSL peptide or activity (measured as cholesteryl esterase) have WAT abnormalities, including low mass, marked heterogeneity of cell diameter, increased diacylglycerol content, and low beta-adrenergic stimulation of adipocyte lipolysis. Three transgenic mouse strains preferentially expressing human HSL in WAT were bred to a HSL-/- background. One, HSL-/- N, expresses normal human HSL (41.3 +/- 9.1% of normal activity); two express a serine-to-alanine mutant (S554A) initially hypothesized to be constitutively active: HSL-/- ML, 50.3 +/- 12.3% of normal, and HSL-/- MH, 69.8 +/- 15.8% of normal. In WAT, HSL-/- N mice resembled HSL+/+ controls in WAT mass, histology, diacylglyceride content, and lipolytic response to beta-adrenergic agents. In contrast, HSL-/- ML and HSL-/- MH mice resembled nontransgenic HSL-/- mice, except that diacylglycerol content and perirenal and inguinal WAT masses approached normal in HSL-/- MH mice. Therefore, 1) WAT expression of normal human HSL markedly improves HSL-/- WAT biochemically, physiologically, and morphologically; 2) similar levels of S554A HSL have a low physiological effect despite being active in vitro; and 3) diacylglycerol accumulation is not essential for the development of the characteristic WAT pathology of HSL-/- mice.     

Parsimony-based test for identifying changes in evolutionary trends for quantitative characters: implications for the origin of the amniotic egg

The origin of the amniotic egg was a major event in vertebrate evolution and is thought to have contributed to the spectacular evolutionary radiation of amniotes. We test one of the most popular scenarios proposed by Carroll in 1970 to explain the origin of the amniotic egg using a novel method based on an asymmetric version of linear parsimony (aka Wagner parsimony) for identifying the most parsimonious split of a tree into two parts between which the evolution of the character is allowed to differ. The new method evaluates the cost of splitting a phylogenetic tree at a given node as the integral, over all pairs of asymmetry parameters, of the most parsimonious costs that can be achieved by using the first parameter on the subtree pending from this node and the second parameter elsewhere. By testing all the nodes, we then obtain the most parsimonious split of a tree with regard to the character values at its tips. Among the nine trees and two characters tested, our method yields a total of 517 parsimonious trend changes in Permo-Carboniferous stegocephalians, a single one of which occurs in a part of the tree (among stem-amniotes) where Carroll's scenario predicts that there should have been distinct changes in body size evolutionary trends. This refutes the scenario because the amniote stem does not appear to have elevated rates of evolutionary trend shifts. Our nodal body size estimates offer less discriminating power, but they likewise fail to find strong support for Carroll's scenario.     

Structure-activity relationship in two series of aminoalkyl substituted coumarin inhibitors of gyrase B.

Two series of aminosubstituted coumarins were synthesised and evaluated in vitro as inhibitors of DNA gyrase and as potential antibacterials. Novel novobiocin-like coumarins, 4-(dialkylamino)methylcoumarins and 4-((2-alkylamino)ethoxy)coumarins, were discovered as gyrase B inhibitors with promising antibacterial activity in vitro.     

A collaborative epidemiological investigation into the criminal fake artesunate trade in South East Asia

Background

Since 1998 the serious public health problem in South East Asia of counterfeit artesunate, containing no or subtherapeutic amounts of the active antimalarial ingredient, has led to deaths from untreated malaria, reduced confidence in this vital drug, large economic losses for the legitimate manufacturers, and concerns that artemisinin resistance might be engendered.

Methods and Findings

With evidence of a deteriorating situation, a group of police, criminal analysts, chemists, palynologists, and health workers collaborated to determine the source of these counterfeits under the auspices of the International Criminal Police Organization (INTERPOL) and the Western Pacific World Health Organization Regional Office. A total of 391 samples of genuine and counterfeit artesunate collected in Vietnam (75), Cambodia (48), Lao PDR (115), Myanmar (Burma) (137) and the Thai/Myanmar border (16), were available for analysis. Sixteen different fake hologram types were identified. High-performance liquid chromatography and/or mass spectrometry confirmed that all specimens thought to be counterfeit (195/391, 49.9%) on the basis of packaging contained no or small quantities of artesunate (up to 12 mg per tablet as opposed to ∼ 50 mg per genuine tablet). Chemical analysis demonstrated a wide diversity of wrong active ingredients, including banned pharmaceuticals, such as metamizole, and safrole, a carcinogen, and raw material for manufacture of methylenedioxymethamphetamine (‘ecstasy''). Evidence from chemical, mineralogical, biological, and packaging analysis suggested that at least some of the counterfeits were manufactured in southeast People''s Republic of China. This evidence prompted the Chinese Government to act quickly against the criminal traders with arrests and seizures.

Conclusions

An international multi-disciplinary group obtained evidence that some of the counterfeit artesunate was manufactured in China, and this prompted a criminal investigation. International cross-disciplinary collaborations may be appropriate in the investigation of other serious counterfeit medicine public health problems elsewhere, but strengthening of international collaborations and forensic and drug regulatory authority capacity will be required.     

Comparative data on the differentiation and growth of bone ornamentation in gnathostomes (Chordata: Vertebrata)

Bone ornamentation, in the form of rounded pits framed by a network of ridges, is a frequent feature among a great diversity of gnathostome taxa. However, the basic osteogenic processes controlling the differentiation and development of these reliefs remain controversial. The present study is a broad comparative survey of this question with the classical methods used in hard tissue histology and paleohistology. Distinct processes, unevenly distributed among taxa, are involved in the creation and growth of pits and ridges. The simplest one is mere differential growth between pit bottom (slow growth) and ridge top (faster growth). The involvement of several complex remodeling processes, with the local succession of resorption and reconstruction cycles, is frequent and occurs in all major gnathostome clades. Some broad, inclusive clades (e.g., Temnospondyli) display consistency in the mechanisms controlling ornamentation, whereas other clades (e.g., Actinopterygii) are characterized by the diversity of the mechanisms involved. If osteogenic mechanisms are taken into account, bone ornamentation should be considered as a character extremely prone to homoplasy. Maximum likelihood (ML) optimizations reveal that the plesiomorphic mechanism creating ornamentation is differential apposition rate over pits (slow growth) and ridges (faster growth). In some taxas e.g., temnospondyls vs lissamphibians or pseudosuchians, bone ornamentation is likely to be a homoplastic feature due to a convergence process driven by similar selective pressures. ML models of character evolution suggest that the presence of resorption in the development of ornamentation may be selectively advantageous, although support for this conclusion is only moderate. J. Morphol. 277:634–670, 2016. © 2016 Wiley Periodicals, Inc.