Endogenous β-glucocerebrosidase activity in Abca12−/−epidermis elevates ceramide levels after topical lipid application but does not restore barrier function

ABCA12 mutations disrupt the skin barrier and cause harlequin ichthyosis. We previously showed Abca12^−/− skin has increased glucosylceramide (GlcCer) and correspondingly lower amounts of ceramide (Cer). To examine why loss of ABCA12 leads to accumulation of GlcCer, de novo sphingolipid synthesis was assayed using [¹⁴C]serine labeling in ex vivo skin cultures. A defect was found in β-glucocerebrosidase (GCase) processing of newly synthesized GlcCer species. This was not due to a decline in GCase function. Abca12^−/− epidermis had 5-fold more GCase protein (n = 4, P < 0.01), and a 5-fold increase in GCase activity (n = 3, P < 0.05). As with Abca12^+/+ epidermis, immunostaining in null skin showed a typical interstitial distribution of the GCase protein in the Abca12^−/− stratum corneum. Hence, we tested whether the block in GlcCer conversion could be circumvented by topically providing GlcCer. This approach restored up to 15% of the lost Cer products of GCase activity in the Abca12^−/− epidermis. However, this level of barrier ceramide replacement did not significantly reduce trans-epidermal water loss function. Our results indicate loss of ABCA12 function results in a failure of precursor GlcCer substrate to productively interact with an intact GCase enzyme, and they support a model of ABCA12 function that is critical for transporting GlcCer into lamellar bodies.     

Ectozoochory as a possible vector enhancing the spread of an alien amphipod Crangonyx pseudogracilis

Most studies of biological invasions refer to the human role in species dispersal but the importance of ectozoochory has scarcely been studied. Thus, we investigated whether the first alien amphipod species found in the Iberian Peninsula, North American Crangonyx pseudogracilis can be dispersed by waterfowl. To do this, we showed experimentally that the amphipod may cling to the plumage and legs of a mallard duck (Anas platyrhynchos) and be transported under controlled laboratory conditions. The probability of the amphipods being transported on duck’s plumage or feet is 1.84 and 1.6%, respectively. Another experiment showed that C. pseudogracilis may stay attached to a flying duck and survive during its flight for a distance of 6.8 km. In addition, we found that this invader can stay alive with a LT₉₀ of 88.6 min when exposed to desiccation. Thus, we conclude that C. pseudogracilis may be successfully transported by the waterfowl for short distances to other waterbodies. Thus, ectozoochory may be an important way of spreading the amphipods in areas where the hydrological network is poorly developed and not interconnected with artificial canals.     

The Role of Viral Introductions in Sustaining Community-Based HIV Epidemics in Rural Uganda: Evidence from Spatial Clustering,Phylogenetics, and Egocentric Transmission Models

Background

It is often assumed that local sexual networks play a dominant role in HIV spread in sub-Saharan Africa. The aim of this study was to determine the extent to which continued HIV transmission in rural communities—home to two-thirds of the African population—is driven by intra-community sexual networks versus viral introductions from outside of communities.

Methods and Findings

We analyzed the spatial dynamics of HIV transmission in rural Rakai District, Uganda, using data from a cohort of 14,594 individuals within 46 communities. We applied spatial clustering statistics, viral phylogenetics, and probabilistic transmission models to quantify the relative contribution of viral introductions into communities versus community- and household-based transmission to HIV incidence. Individuals living in households with HIV-incident (n = 189) or HIV-prevalent (n = 1,597) persons were 3.2 (95% CI: 2.7–3.7) times more likely to be HIV infected themselves compared to the population in general, but spatial clustering outside of households was relatively weak and was confined to distances <500 m. Phylogenetic analyses of gag and env genes suggest that chains of transmission frequently cross community boundaries. A total of 95 phylogenetic clusters were identified, of which 44% (42/95) were two individuals sharing a household. Among the remaining clusters, 72% (38/53) crossed community boundaries. Using the locations of self-reported sexual partners, we estimate that 39% (95% CI: 34%–42%) of new viral transmissions occur within stable household partnerships, and that among those infected by extra-household sexual partners, 62% (95% CI: 55%–70%) are infected by sexual partners from outside their community. These results rely on the representativeness of the sample and the quality of self-reported partnership data and may not reflect HIV transmission patterns outside of Rakai.

Conclusions

Our findings suggest that HIV introductions into communities are common and account for a significant proportion of new HIV infections acquired outside of households in rural Uganda, though the extent to which this is true elsewhere in Africa remains unknown. Our results also suggest that HIV prevention efforts should be implemented at spatial scales broader than the community and should target key populations likely responsible for introductions into communities. Please see later in the article for the Editors'' Summary     

Comt1 genotype and expression predicts anxiety and nociceptive sensitivity in inbred strains of mice

Catechol‐O‐methyltransferase (COMT) is a ubiquitously expressed enzyme that maintains basic biologic functions by inactivating catechol substrates. In humans, polymorphic variance at the COMT locus has been associated with modulation of pain sensitivity and risk for developing psychiatric disorders. A functional haplotype associated with increased pain sensitivity was shown to result in decreased COMT activity by altering mRNA secondary structure‐dependent protein translation. However, the exact mechanisms whereby COMT modulates pain sensitivity and behavior remain unclear and can be further studied in animal models. We have assessed Comt1 gene expression levels in multiple brain regions in inbred strains of mice and have discovered that Comt1 is differentially expressed among the strains, and this differential expression is cis‐regulated. A B2 short interspersed nuclear element (SINE) was inserted in the 3′‐untranslated region (3′‐UTR) of Comt1 in 14 strains generating a common haplotype that correlates with gene expression. Experiments using mammalian expression vectors of full‐length cDNA clones with and without the SINE element show that strains with the SINE haplotype (+SINE) have greater Comt1 enzymatic activity. +SINE mice also exhibit behavioral differences in anxiety assays and decreased pain sensitivity. These results suggest that a haplotype, defined by a 3′‐UTR B2 SINE element, regulates Comt1 expression and some mouse behaviors.     

Blue sucker habitat use in a regulated Texas river: implications for conservation and restoration

Environmental Biology of Fishes - Species conservation requires a clear understanding of habitat availability and subsequent use of those habitats. In cases where species declines have occurred and...     

Moderation of Arabidopsis Root Stemness by CLAVATA1 and ARABIDOPSIS CRINKLY4 Receptor Kinase Complexes

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Highlights? CLV1 receptor kinase regulates stemness in Arabidopsis root and shoot meristems ? CLV1 and ACR4 form homo- and heteromeric complexes as shown by a novel FRET assay ? CLV1/ACR4 complexes differ in composition between plasma membrane and plasmodesmata ? CLV1/ACR4 complexes regulate distal root meristem maintenance     

Quantitative collection of milk and active recombinant proteins from the mammary glands of transgenic mice

Summary

Transgenic mice expressing foreign genes specifically in their mammary glands have been obtained by several groups in the world. The mouse is generally considered as a good reference animal to evaluate the efficiency of gene constructs to be used in larger mammals for the preparation of the corresponding recombinant proteins at an industrial scale. The method described here shows that mammary glands from lactating mice separated from their pups for one day spontaneously released 1.5 ml milk when stored at O'C. The proteins of milk obtained by this method were essentially similar to those obtained after milking. Human growth hormone (hGH) gene under the control of the rabbit whey acidic (WAP) gene promoter was expressed at a high level in the milk of transgenic mice (4 mg/ml milk in the mice examined here). hGH was present in milk obtained after milking or after the incubation of the mammary glands at O'C. In both cases, the hormone was present in essentially similar concentration, undegraded and biologically active (as judged by its prolactin‐like activity). The method depicted here is very simple and can be applied easily to many mice. Its major limitation is that it implies the breeding and the sacrifice of a relatively large number of animals. One gram of crude recombinant protein can be virtually obtained in this way with about 200 lactating mice from their milk containing the proteins at the concentration of 3‐4 mg/ml. The milk of transgenic mice can therefore be considered as a practical source of recombinant proteins for biochemical and pharmaceutical studies.     

Silver(I) complexes with hydantoins and allantoin: synthesis, crystal and molecular structure, cytotoxicity and pharmacokinetics

Coordination polymers [Ag(L^1,3)]_n (L¹ = hydantoin, L³ = 5,5-dimethylhydantoin), {[Ag(L²)]^.0.5H₂O}_n (L² = 1-methylhydantoin) and [Ag(NH₃)(L⁴)]_n (L⁴ = allantoin) were prepared and characterized by elemental analysis, spectroscopic (IR, FTIR and NMR), thermal and mass spectrometry methods. The crystal structure of {[Ag(1-methylhydantoin)]·0,5H₂O}_n was determined and analyzed. Three 1-methylhydantoinate ligands create a T-shape (CN = 3) coordination sphere around the Ag⁺ ion. Additionally, a short Ag?Ag distance of 2.997 Å was found in the structure resulting in the expanded [3 + 2] environment of a distorted square shape. The [Ag(L²)] entities are bound to each other by the bridging organic ligands. Thus a two-dimensional coordination polymer is created with water molecules located between the layers. In contrast to hydantoins, the allantoin complex contains an additional ammonia molecule in the coordination sphere. Moreover, in the Ag-alla complex the M-organic ligand binding site is shifted to the N-atom of the ureid chain. Free ligands are cytotoxically inactive against human MCF-7 and A549 cancer cell lines and mouse fibroblasts Balb/3T3. The silver hydantoin complexes exhibit a very strong activity against these lines. (The introduction of the methyl groups to the ring slightly increases resistance only against the A549 cell line.) In contrast, the silver complex of allantoin shows only a weak activity which may be related to the presence of the cytotoxic ammonia group in the composition of the compound and/or the different binding site of the ligand. Calculated in silico physiochemical parameters are promising for the future application of the complexes as drugs.