Cryptococcus neoformans varieties from material under the canopies of eucalyptus trees and pigeon dropping samples from four major cities in Jordan

To our best knowledge, any study related to the ecological distribution of Cryptococcus neoformans in Jordan does not exist in the medical literature. In order to determine the environmental occurrence of both varieties of Cryptococcus neoformans in Jordan, pigeon droppings and material under the canopies of eucalyptus trees were collected from four major cities of this country. For the isolation of Cryptococcus neoformans variety gattii from environmental sources, 500 samples of the mixed soil debris, including tree materials, under the eucalyptus trees from cities of Amman, Irbid, Jerash, and Ajlun were collected. Also, 509 samples of pigeon droppings were collected from the same cities for the isolation of Cryptococcus neoformans variety neoformans. After inoculating the samples onto modified Staib agar medium in Petri dishes, a total of 336 melanoid yeast colonies were picked up during screening process. At the end of serial mycological studies, none of these isolates was identified as Cryptococcus neoformans, but all were Cryptococcus species other than C. neoformans. For determining the exact status, more extensive environmental studies need to be done in the future.     

Interaction of microtubule-associated protein-2 and p63: a new link between microtubules and rough endoplasmic reticulum membranes in neurons

Neurons are polarized cells presenting two distinct compartments, dendrites and an axon. Dendrites can be distinguished from the axon by the presence of rough endoplasmic reticulum (RER). The mechanism by which the structure and distribution of the RER is maintained in these cells is poorly understood. In the present study, we investigated the role of the dendritic microtubule-associated protein-2 (MAP2) in the RER membrane positioning by comparing their distribution in brain subcellular fractions and in primary hippocampal cells and by examining the MAP2-microtubule interaction with RER membranes in vitro. Subcellular fractionation of rat brain revealed a high MAP2 content in a subfraction enriched with the endoplasmic reticulum markers ribophorin and p63. Electron microscope morphometry confirmed the enrichment of this subfraction with RER membranes. In cultured hippocampal neurons, MAP2 and p63 were found to concomitantly compartmentalize to the dendritic processes during neuronal differentiation. Protein blot overlays using purified MAP2c protein revealed its interaction with p63, and immunoprecipitation experiments performed in HeLa cells showed that this interaction involves the projection domain of MAP2. In an in vitro reconstitution assay, MAP2-containing microtubules were observed to bind to RER membranes in contrast to microtubules containing tau, the axonal MAP. This binding of MAP2c microtubules was reduced when an anti-p63 antibody was added to the assay. The present results suggest that MAP2 is involved in the association of RER membranes with microtubules and thereby could participate in the differential distribution of RER membranes within a neuron.     

Presentation of Integrins on Leukocyte Microvilli: A Role for the Extracellular Domain in Determining Membrane Localization

Adhesion of blood leukocytes to the endothelium involves multiple steps including initial attachment (tethering), rolling, and firm arrest. Presentation of adhesion molecules on leukocyte microvilli can substantially enhance tethering. Localization of L-selectin to microvilli and of CD44 to the planar cell body have been shown to depend upon their transmembrane and cytoplasmic domains. We investigated the role of leukocyte integrin transmembrane and cytoplasmic domains in initiating adhesion under flow and in microvillous localization. Integrins α4β7, αLβ2, and αMβ2 were heterologously expressed in K562 cells. α4β7 initiated adhesion under flow and localized to microvilli, whereas β2 integrins did not initiate adhesion and localized to the cell body. Chimeric integrins were produced by replacing the α4β7 cytoplasmic and/or transmembrane domains with the homologous domains of αLβ2 or αMβ2. Unexpectedly, these chimeras efficiently mediated adhesion to the α4β7 ligand mucosal addressin cell adhesion molecule–1 under flow and localized to microvilli. Therefore, differences between the transmembrane and cytoplasmic domains of α4 and β2 integrins do not account for differences in ability to support attachment under flow or in membrane localization. Integrins α4β1, α5β1, α6Aβ1, αvβ3, and αEβ7 also localized to microvilli. Transmembrane proteins known or suspected to associate with extracellular domains of microvillous integrins, including tetraspans and CD47, were concentrated on microvilli as well. These findings suggest that interactions between the extracellular domains of integrins and associated proteins could direct the assembly of multimolecular complexes on leukocyte microvilli.     

Mutation in LIM2 Is Responsible for Autosomal Recessive Congenital Cataracts

PurposeTo identify the molecular basis of non-syndromic autosomal recessive congenital cataracts (arCC) in a consanguineous family.MethodsAll family members participating in the study received a comprehensive ophthalmic examination to determine their ocular phenotype and contributed a blood sample, from which genomic DNA was extracted. Available medical records and interviews with the family were used to compile the medical history of the family. The symptomatic history of the individuals exhibiting cataracts was confirmed by slit-lamp biomicroscopy. A genome-wide linkage analysis was performed to localize the disease interval. The candidate gene, LIM2 (lens intrinsic membrane protein 2), was sequenced bi-directionally to identify the disease-causing mutation. The physical changes caused by the mutation were analyzed in silico through homology modeling, mutation and bioinformatic algorithms, and evolutionary conservation databases. The physiological importance of LIM2 to ocular development was assessed in vivo by real-time expression analysis of Lim2 in a mouse model.ResultsOphthalmic examination confirmed the diagnosis of nuclear cataracts in the affected members of the family; the inheritance pattern and cataract development in early infancy indicated arCC. Genome-wide linkage analysis localized the critical interval to chromosome 19q with a two-point logarithm of odds (LOD) score of 3.25. Bidirectional sequencing identified a novel missense mutation, c.233G>A (p.G78D) in LIM2. This mutation segregated with the disease phenotype and was absent in 192 ethnically matched control chromosomes. In silico analysis predicted lower hydropathicity and hydrophobicity but higher polarity of the mutant LIM2-encoded protein (MP19) compared to the wild-type. Moreover, these analyses predicted that the mutation would disrupt the secondary structure of a transmembrane domain of MP19. The expression of Lim2, which was detected in the mouse lens as early as embryonic day 15 (E15) increased after birth to a level that was sustained through the postnatal time points.ConclusionA novel missense mutation in LIM2 is responsible for autosomal recessive congenital cataracts.