Genetics,Morphology, Advertisement Calls,and Historical Records Distinguish Six New Polyploid Species of African Clawed Frog (Xenopus,Pipidae) from West and Central Africa

African clawed frogs, genus Xenopus, are extraordinary among vertebrates in the diversity of their polyploid species and the high number of independent polyploidization events that occurred during their diversification. Here we update current understanding of the evolutionary history of this group and describe six new species from west and central sub-Saharan Africa, including four tetraploids and two dodecaploids. We provide information on molecular variation, morphology, karyotypes, vocalizations, and estimated geographic ranges, which support the distinctiveness of these new species. We resurrect Xenopus calcaratus from synonymy of Xenopus tropicalis and refer populations from Bioko Island and coastal Cameroon (near Mt. Cameroon) to this species. To facilitate comparisons to the new species, we also provide comments on the type specimens, morphology, and distributions of X. epitropicalis, X. tropicalis, and X. fraseri. This includes significantly restricted application of the names X. fraseri and X. epitropicalis, the first of which we argue is known definitively only from type specimens and possibly one other specimen. Inferring the evolutionary histories of these new species allows refinement of species groups within Xenopus and leads to our recognition of two subgenera (Xenopus and Silurana) and three species groups within the subgenus Xenopus (amieti, laevis, and muelleri species groups).     

The Role of Temporal Information in Perisaccadic Mislocalization

In dynamic environments, it is crucial to accurately consider the timing of information. For instance, during saccades the eyes rotate so fast that even small temporal errors in relating retinal stimulation by flashed stimuli to extra-retinal information about the eyes’ orientations will give rise to substantial errors in where the stimuli are judged to be. If spatial localization involves judging the eyes’ orientations at the estimated time of the flash, we should be able to manipulate the pattern of mislocalization by altering the estimated time of the flash. We reasoned that if we presented a relevant flash within a short rapid sequence of irrelevant flashes, participants’ estimates of when the relevant flash was presented might be shifted towards the centre of the sequence. In a first experiment, we presented five bars at different positions around the time of a saccade. Four of the bars were black. Either the second or the fourth bar in the sequence was red. The task was to localize the red bar. We found that when the red bar was presented second in the sequence, it was judged to be further in the direction of the saccade than when it was presented fourth in the sequence. Could this be because the red bar was processed faster when more black bars preceded it? In a second experiment, a red bar was either presented alone or followed by two black bars. When two black bars followed it, it was judged to be further in the direction of the saccade. We conclude that the spatial localization of flashed stimuli involves judging the eye orientation at the estimated time of the flash.     

Inaccuracy of Venous Point-of-Care Glucose Measurements in Critically Ill Patients: A Cross-Sectional Study

Introduction

Current guidelines and consensus recommend arterial and venous samples as equally acceptable for blood glucose assessment in point-of-care devices, but there is limited evidence to support this recommendation. We evaluated the accuracy of two devices for bedside point-of-care blood glucose measurements using arterial, fingerstick and catheter venous blood samples in ICU patients, and assessed which factors could impair their accuracy.

Methods

145 patients from a 41-bed adult mixed-ICU, in a tertiary care hospital were prospectively enrolled. Fingerstick, central venous (catheter) and arterial blood (indwelling catheter) samples were simultaneously collected, once per patient. Arterial measurements obtained with Precision PCx, and arterial, fingerstick and venous measurements obtained with Accu-chek Advantage II were compared to arterial central lab measurements. Agreement between point-of-care and laboratory measurements were evaluated with Bland-Altman, and multiple linear regression models were used to investigate interference of associated factors.

Results

Mean difference between Accu-chek arterial samples versus central lab was 10.7 mg/dL (95% LA -21.3 to 42.7 mg/dL), and between Precision PCx versus central lab was 18.6 mg/dL (95% LA -12.6 to 49.5 mg/dL). Accu-chek fingerstick versus central lab arterial samples presented a similar bias (10.0 mg/dL) but a wider 95% LA (-31.8 to 51.8 mg/dL). Agreement between venous samples with arterial central lab was the poorest (mean bias 15.1 mg/dL; 95% LA -51.7 to 81.9). Hyperglycemia, low hematocrit, and acidosis were associated with larger differences between arterial and venous blood measurements with the two glucometers and central lab. Vasopressor administration was associated with increased error for fingerstick measurements.

Conclusions

Sampling from central venous catheters should not be used for glycemic control in ICU patients. In addition, reliability of the two evaluated glucometers was insufficient. Error with Accu-chek Advantage II increases mostly with central venous samples. Hyperglycemia, lower hematocrit, acidosis, and vasopressor administration increase measurement error.     

The byssus of the zebra mussel (Dreissena polymorpha): spatial variations in protein composition

The notorious biofouling organism Dreissena polymorpha (the zebra mussel) attaches to a variety of surfaces using a byssus, a series of protein threads that connect the animal to adhesive plaques secreted onto hard substrata. Here, the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) to characterize the composition of different regions of the byssus is reported. All parts of the byssus show mass peaks corresponding to small proteins in the range of 3.7-7 kDa, with distinctive differences between different regions. Indeed, spectra from thread and plaques are almost completely non-overlapping. In addition, several peaks were identified that are unique to the interfacial region of the plaque, and therefore likely represent specialized adhesive proteins. These results indicate a high level of control over the distribution of proteins, presumably with different functions, in the byssus of this freshwater species.     

A review on the potential of triploid tench for aquaculture

Performance and physiological traits and health of spontaneous and induced triploid tench are reviewed. Triploidy is best induced with cold shock; with triploids exhibiting 13.5–51.5% better weight gain, 2.69–3.94% higher slaughtering value, 20–60% lower gonadosomatic index, 0.9–4.5% higher dry matter in flesh and up to 107% more flesh fat than diploids, if farmed untill post sexual maturity. Triploids exhibit more abdominal fat and less polyunsaturated fatty acids of the n-3 and n-6 groups in the flesh. Triploid females are sterile, while triploid males may produce aneuploid spermatozoa with varying DNA content (1–1.9n) which may initiate development of embryos. Triploids have milder seasonal dynamics in their erythrocyte profile than the diploids. Thinner diffusion distance in gills of triploids than in diploids is interpreted as adaptation to lower aerobic capacity. Triploids show neither stronger tendencies to anatomic malformations, nor have bigger affinity to parasitic diseases than the diploids. Production of triploid tench could be an economically interesting method of farming to higher marketable weight, bringing a relatively high product quality.     

Autosomal-Recessive Hypophosphatemic Rickets Is Associated with an Inactivation Mutation in the ENPP1 Gene

Human disorders of phosphate (Pi) handling and hypophosphatemic rickets have been shown to result from mutations in PHEX, FGF23, and DMP1, presenting as X-linked recessive, autosomal-dominant, and autosomal-recessive patterns, respectively. We present the identification of an inactivating mutation in the ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) gene causing autosomal-recessive hypophosphatemic rickets (ARHR) with phosphaturia by positional cloning. ENPP1 generates inorganic pyrophosphate (PPi), an essential physiologic inhibitor of calcification, and previously described inactivating mutations in this gene were shown to cause aberrant ectopic calcification disorders, whereas no aberrant calcifications were present in our patients. Our surprising result suggests a different pathway involved in the generation of ARHR and possible additional functions for ENPP1.     

Novel cationic vesicle platform derived from vernonia oil for efficient delivery of DNA through plant cuticle membranes

Novel cationic amphiphilic compounds were prepared from vernonia oil, a natural epoxidized triglyceride, and studied with respect to vesicle formation, encapsulation of biomaterials such as DNA, and their physical stability and transport through isolated plant cuticle membranes. The amphiphiles studied were a single-headed compound III (a quaternary ammonium head group with two alkyl chains) and a triple-headed compound IV, which is essentially three molecules of compound III bound together through a glycerol moiety. Vesicles of the two amphiphiles, prepared by sonication in water and solutions of uranyl acetate or the herbicide 2,4-D (2,4-dichloropenoxy acetic acid), were examined by TEM, SEM, AFM, and confocal laser systems and had a spherical shape which encapsulated the solutes with diameters between 40 and 110 nm. Vesicles from amphiphile IV could be made large enough to encapsulate a condensed 5.2kb DNA plasmid (pJD328). Vesicles of amphiphile IV were also shown to pass intact across isolated plant cuticle membranes and the rate of delivery of encapsulated radio-labeled 2,4-D through isolated plant cuticle membranes obtained with these vesicles was clearly greater in comparison to liposomes prepared from dipalmitopyl phosphatidylcholine (DPPC) and the control, nonencapsulated 2,4-D. Vesicles from amphiphiles III and IV were found to be more stable than those of liposomes from DPPC. The data indicate the potential of vesicles prepared from the novel amphiphile IV to be a relatively efficient nano-scale delivery system to transport DNA and other bioactive agents through plant biological barriers. This scientific approach may open the way for further development of efficient in vivo plant transformation systems.     

A finite shell element for heart mitral valve leaflet mechanics, with large deformations and 3D constitutive material model

This paper presents a shell finite element formulation appropriate for simulating the heart valve leaflet mechanics, including three-dimensional (3D) stress and strain effects. A 4-node mixed-interpolation shell is formulated in convected coordinates. This shell model is made capable of handling arbitrary 3D material models by use of an algorithm that satisfies the shell stress assumption at every element integration point. A method for tracking the fiber direction is incorporated. The resulting shell element operates under the same conditions as a standard 4-node shell element with 5 degrees of freedom per node, but extends the modeling capabilities to handle large-deformation and anisotropic behavior.     

Autosomal recessive ichthyosis with hypotrichosis caused by a mutation in ST14, encoding type II transmembrane serine protease matriptase

In this article, we describe a novel autosomal recessive ichthyosis with hypotrichosis syndrome, characterized by congenital ichthyosis associated with abnormal hair. Using homozygosity mapping, we mapped the disease locus to 11q24.3-q25. We screened the ST14 gene, which encodes matriptase, since transplantation of skin from matriptase(-/-)-knockout mice onto adult athymic nude mice has been shown elsewhere to result in an ichthyosislike phenotype associated with almost complete absence of erupted pelage hairs. Mutation analysis revealed a missense mutation, G827R, in the highly conserved peptidase S1-S6 domain. Marked skin hyperkeratosis due to impaired degradation of the stratum corneum corneodesmosomes was observed in the affected individuals, which suggests that matriptase plays a significant role in epidermal desquamation.     

Human Rap1 modulates TRF2 attraction to telomeric DNA

More than two decades of genetic research have identified and assigned main biological functions of shelterin proteins that safeguard telomeres. However, a molecular mechanism of how each protein subunit contributes to the protecting function of the whole shelterin complex remains elusive. Human Repressor activator protein 1 (Rap1) forms a multifunctional complex with Telomeric Repeat binding Factor 2 (TRF2). Rap1–TRF2 complex is a critical part of shelterin as it suppresses homology-directed repair in Ku 70/80 heterodimer absence. To understand how Rap1 affects key functions of TRF2, we investigated full-length Rap1 binding to TRF2 and Rap1–TRF2 complex interactions with double-stranded DNA by quantitative biochemical approaches. We observed that Rap1 reduces the overall DNA duplex binding affinity of TRF2 but increases the selectivity of TRF2 to telomeric DNA. Additionally, we observed that Rap1 induces a partial release of TRF2 from DNA duplex. The improved TRF2 selectivity to telomeric DNA is caused by less pronounced electrostatic attractions between TRF2 and DNA in Rap1 presence. Thus, Rap1 prompts more accurate and selective TRF2 recognition of telomeric DNA and TRF2 localization on single/double-strand DNA junctions. These quantitative functional studies contribute to the understanding of the selective recognition of telomeric DNA by the whole shelterin complex.