The sexual segment of hemidactylus turcicus and the evolution of sexual segment location in squamata

The kidneys of the Mediterranean Gecko, Hemidactylus turcicus (Gekkonidae), were investigated using light and electron microscopy with the primary focus placed on morphology of the sexual segment of the kidney. The nephrons of male H. turcicus are composed of five distinct regions: 1) a renal corpuscle and glomerulus, 2) a proximal convoluted tubule, 3) an intermediate segment, 4) a distal convoluted tubule, and 5) the sexual segment of the kidney/collecting duct. Female H. turcicus is similar but lack a sexual segment of the kidney. The sexual segment of the kidney is hypertrophied during the months of March through August, which corroborates previous reports of reproductive activity. During inactive months, the sexual segment of the kidney is nondiscernable from the collecting ducts. The sexual segment consists of tall columnar epithelial cells with basally positioned nuclei. Perinuclear Golgi complexes and rough endoplasmic reticulum are present. Secretory granules, which fill the apices of the epithelial cells, are electron dense and released into the lumen by a merocrine secretory process. Narrow intercellular canaliculi separate each epithelial cell and are sealed by tight junctions at the luminal aspect. Basally, leukoctyes are observed within the intercellular canaliculi and outside the basal lamina. Mast cells can be found just outside the basal lamina in close association with renal capillaries. The sexual segment of the kidney of H. turcicus is similar to that of three unrelated lizards for which ultrastructure was investigated with secretion mode being the major difference Also, H. turcicus is similar to most other lizards in that complete regression occurs during reproductive inactivity, but differs in this trait from the skink, Scincella lateralis, and most snakes which display a hypertrophied sexual segment of the kidney throughout the entire year. Although some unique similarities appear during the optimization, no direct patterns or directions are observed, and only the molecular based phylogeny resolves the ancestral condition of the Squamata as the sexual segment of the kidney being observed in the distal convoluted tubule, collecting duct, and ureter. J. Morphol., 2011. © 2011 Wiley‐Liss, Inc.     

SARS-CoV-2 in patients with cancer: possible role of mimicry of human molecules by viral proteins and the resulting anti-cancer immunity

A few reports suggest that molecular mimicry can have a role in determining the more severe and deadly forms of COVID-19, inducing endothelial damage, disseminated intravascular coagulation, and multiorgan failure. Heat shock proteins/molecular chaperones can be involved in these molecular mimicry phenomena. However, tumor cells can display on their surface heat shock proteins/molecular chaperones that are mimicked by SARS-CoV-2 molecules (including the Spike protein), similarly to what happens in other bacterial or viral infections. Since molecular mimicry between SARS-CoV-2 and tumoral proteins can elicit an immune reaction in which antibodies or cytotoxic cells produced against the virus cross-react with the tumor cells, we want to prompt clinical studies to evaluate the impact of SARS-CoV-2 infection on prognosis and follow up of various forms of tumors. These topics, including a brief historical overview, are discussed in this paper.     

The ultrastructure of spermatid development during spermiogenesis within the rosebelly lizard,Sceloporus variabilis (Reptilia,Squamata, Phrynosomatidae)

Several recent studies have mapped out the characters of spermiogenesis within several species of squamates. Many of these data have shown both conserved and possibly apomorphic morphological traits that could be important in future phylogenetic analysis within Reptilia. There, however, has not been a recent study that compares spermiogenesis and its similarities or differences between two species of reptile that reside in the same genus. Thus, the present analysis details the changes to spermiogenesis in Sceloporus variabilis and then compares spermatid morphologies to that of Sceloporus bicanthalis. Many of the morphological changes that the spermatids undergo in these two species are similar or conserved, which is similar to what has been reported in other squamates. There are six main character differences that can be observed during the development of the spermatids between these two sceloporid lizards. They include the presence (S. variabilis) or absence (S. bicanthalis) of a mitochondrial/endoplasmic reticulum complex near the Golgi apparatus during acrosome development, a shallow (S. variabilis) or deep (S. bicanthalis) nuclear indentation that accommodates the acrosomal vesicle, filamentous (S. variabilis) or granular (S. bicanthalis) chromatin condensation, no spiraling (S. variabilis) or spiraling (S. bicanthalis) of chromatin during condensation, absence (S. variabilis) or presence (S. bicanthalis) of the longitudinal manchette microtubules, and the lack of (S. variabilis) or presence (S. bicanthalis) of nuclear lacunae. This is the first study that compares spermiogenic ultrastructural characters between species within the same genus. The significance of the six character differences between two distantly related species within Sceloporus is still unknown, but these data do suggest that spermiogenesis might be a good model to study the hypothesis that spermatid ontogeny is species specific. J. Morphol. 275:258–268, 2014. © 2013 Wiley Periodicals, Inc.     

Rheological properties of cross-linked hyaluronan-gelatin hydrogels for tissue engineering

Hydrogels that mimic the natural extracellular matrix (ECM) are used in three-dimensional cell culture, cell therapy, and tissue engineering. A semi-synthetic ECM based on cross-linked hyaluronana offers experimental control of both composition and gel stiffness. The mechanical properties of the ECM in part determine the ultimate cell phenotype. We now describe a rheological study of synthetic ECM hydrogels with storage shear moduli that span three orders of magnitude, from 11 to 3 500 Pa, a range important for engineering of soft tissues. The concentration of the chemically modified HA and the cross-linking density were the main determinants of gel stiffness. Increase in the ratio of thiol-modified gelatin reduced gel stiffness by diluting the effective concentration of the HA component.