Unexpected morphological variability in the eggshells of the South American caimans Caiman latirostris and Caiman yacare

Eggshell morphology is a valuable indicator of the local conditions within the nests of modern crocodilians and birds. In contrast to these latter, the anatomical structure of the eggshells of most crocodilian species is practically unknown. Here, we provide the first characterization of crocodilian eggshells, using x-ray micro-CT scans. We studied eggshells of Caiman latirostris and Caiman yacare from various developmental stages that coincide with the beginning of embryonic ossification. The new 3D renderings revealed complex ornamentation, unique among crocodilians, and amphora-shaped pore canals, some of which converge in single pore openings. We also documented a high density of pore canals with a gas diffusion capacity 45 times higher than the average predicted for modern avian eggshells. The external ornamentation and the thickness of the compact layer of the eggshells (i.e. excluding ornamentation) showed ontogenetic and interspecific differences that could be related to nesting materials and nesting areas selected by each species. The shell features described here evidence a greater structural complexity than previously recognized in phylogenetically close, sympatric crocodilian species. Further comprehensive morphological analyses on other modern and fossil crocodilian eggshells using micro-CT technology will shed new light on the evolution of reproductive strategies in this intriguing archosaur clade.Fil: Hechenleitner, Esteban Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Fernandez Blanco, María Victoria. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Núñez Campero, Segundo Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Fiorelli, Lucas Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Bona, Paula. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin

Diseño de medios quirales basados en estructuras individuales bidimensionales

In this paper, we present a new way of constructing chiral media, in 8.2-12.4 GHz band, starting from achiral individual metallic elements (right angle). We showed that an appropriate distribution of such inclusions in a dielectric host responds in a manner consistent to that obtained with other media constructed using chiral metal inclusions. Appropriately modifying the size and spatial distribution of right angles is possible to model the response of these media. The media manufactured by the inclusion of right angles can be fabricated using technology printed circuit board (PCB).Ingeniería, Industria y Construcció

Diseño de medios quirales basados en la distribución ordenada de manivelas

In this communication, the experimental results obtained from the measurements of evenly distributed metallic cranks on a dielectric plate substrate is presented. The effect we have analyzed is the rotation of the polarization plane of an electromagnetic wave, both in free space and inside a circular waveguide. It is shown that the rotation of the polarization plane by some distributions of cranks, with specific symmetry properties, can be explicitly ascribed to a chirality effect.Ingeniería, Industria y Construcció

Actividad electromagnética de medios quirales basados en manivelas

Materials with electromagnetic activity are usually made by spreading helices inclusions into a host medium. In previous work, a new manufacturing technique based on the inclusion of few three segment wire hooks (cranks) was presented and the rotation of the polarisation angle in circular waveguide discussed. Here we present that the random inclusion of many cranks into a host medium produces electromagnetically active materials. Based on a free-wave experimental system, we have found that the transmitted wave through the material is rotated with respect to the incident one. First results seem to be in agreement with the typical behaviour of chiral media at the resonant frequency.Ingeniería, Industria y Construcció

Developing Chiral Media Based on the Inclusion of Metallic Cranks

A review of the manufacturing techniques for developing chiral media based on the inclusion of cranks is presented. Chirality is usually obtained by a randomdistribution of helices in a host medium. Here the chiral elements are obtained by bending thin metal-wires in three segments. We will show that a random distribution of cranks is able of rotate the polarization angle of the transmitted linearly polarized wave at microwave frequencies. This effect can be enhanced by the precise location of cranks forming a 2D periodic lattice. Several structures are analyzed looking for isotropy, reciprocity and homogeneity.Ingeniería, Industria y Construcció

Estudio experimental de inserciones metálicas quirales en medios guiados

A new manufacturing technique of chiral material and first measurements of the rotation of the polarisation angle are presented. We have developed a flexible and low cost method to produce chiral media based on the inclusion of three segment wire hook (crank) in lossless dielectric medium. Cylindrical samples are placed into a section of circular waveguide propagating an initial single TE plane-polarised mode in the X band. The S21 parameter is measured with a rotation of the output waveguide. We have found rotations of the polarised wave produced by the samples. The effect of chirality is analyzed by chiral crank versus non-chiral staples comparison.Ingeniería, Industria y Construcció

Metamateriales Quirales Basados en Manivelas de Cinco Segmentos

A new structure formed by five segments cranks is here presented. By using numerical simulations, we show that a material composed by a 2D periodical distribution of a unit cell based on such structures is able to produce electromagnetic rotatory dispersion and circular dichroism. The symmetry requirements on the unit cell are analyzed in order to obtain a material with homogeneous and isotropic behavior for normal incidence. The material can exhibit several resonant frequencies, where the rotation angle reaches a peak of ±90º and the transmitted wave changes from linear to elliptical polarization.Ingeniería, Industria y Construcció

Repurposing drugs for highly prevalent diseases: pentoxifylline, an old drug and a new opportunity for diabetic kidney disease

Diabetic kidney disease is one of the most frequent complications in patients with diabetes and constitutes a major cause of end-stage kidney disease. The prevalence of diabetic kidney disease continues to increase as a result of the growing epidemic of diabetes and obesity. Therefore, there is mounting urgency to design and optimize novel strategies and drugs that delay the progression of this pathology and contain this trend. The new approaches should go beyond the current therapy focussed on the control of traditional risk factors such as hyperglycaemia and hypertension. In this scenario, drug repurposing constitutes an economic and feasible approach based on the discovery of useful activities for old drugs. Pentoxifylline is a nonselective phosphodiesterase inhibitor currently indicated for peripheral artery disease. Clinical trials and meta-analyses have shown renoprotection secondary to anti-inflammatory and antifibrotic effects in diabetic patients treated with this old known drug, which makes pentoxifylline a candidate for repurposing in diabetic kidney diseaseThis work was supported by Instituto de Salud Carlos III (ISCIII): PI07/0870, PI15/00298, PI16/02057, PI16/00024, PI19/00035, PI20/00744, PI21/00251, PI21/01037, PI19/00815, DTS18/00032 ISCIII-RETIC REDinREN RD16/0009, and RICORS2040. We acknowledge cofunding by Fondo Europeo de Desarrollo Regional [FEDER], Unión Europea [‘Una forma de hacer Europa’]. J.D.-C. is the recipient of a contract from Miguel Servet Program (CP20/00122) of the ISCIII. A.G.-L. and C.F. are recipients of contracts from Agencia Canaria de Investigación Innovación y Sociedad de la Información del Gobierno de Canarias (ACIISI) (TESIS2021010045 and TESIS2018010110). E.M.-N. is funded by a research contract from REDinREN-ISCIII (RD16/0009/0022). V.G.- T. is supported by Cabildo de Tenerife, TF Innova, Fondo de Desarrollo de Canarias (FDCAN) and Marco Estratégico de Desarrollo Insular (MEDI), in the Agustín de Betancourt programm

Sodium-glucose co-transporter-2 inhibitors increase Klotho in patients with diabetic kidney disease: a clinical and experimental study

Sodium-glucose co-transporter-2 inhibitors (SGLT2i) provide cardiorenal protection. However, the molecular mechanisms remain poorly understood. We explored the impact of SGLT2i on Klotho, a kidney-derived protein with antiaging, renal-protective and heart-protective properties. A real world prospective observational study addressed the impact of initiating SGLT2i (canagliflozin, dapagliflozin, empagliflozin) or dipeptidyl peptidase-4 inhibitors (DPP4i) in patients with early diabetic kidney disease (DKD). Serum and urinary soluble Klotho, albuminuria and serum and urinary tumor necrosis factor-alpha (TNFa) were measured. The effect of SGLT2i on Klotho mRNA and protein was explored in vitro in kidney proximal tubular cells stressed with high glucose concentrations to simulate the diabetic milieu, albumin to simulate albuminuria, and the inflammatory cytokine TWEAK to simulate the inflammatory environment in DKD. Baseline urinary Klotho was negatively associated with albuminuria (r − 0.45, P < 0.001) and urinary TNFa (r − 0.40, P < 0.01). Both DPP4i and SGLT2i reduced HbA1c similarly, but only SGLT2i decreased eGFR, albuminuria and urinary TNFa and increased (P < 0.001) serum (5.2 %) and urinary Klotho (38.9 %). Changes in urinary TNFa (β − 0.53, P = 0.001) and albuminuria (β − 0.31, P < 0.05) were independently associated with changes in urinary Klotho (adjusted R2 = 0.54, P < 0.001). Studies in renal tubular cells demonstrated that high glucose, albumin and TWEAK decreased Klotho mRNA expression and protein levels, an effect similarly prevented by SGLT2i. SGLT2i increase Klotho availability in type 2 diabetic patients with poorly controlled diabetes and early DKD, as well as in stressed tubular cells. This effect on Klotho may contribute to the kidney and heart protection afforded by SGLT2iThe authors thank all the study participants, without whom this study would not have been possible. The authors acknowledge the support from Instituto de Salud Carlos III (ISCIII) FIS/Fondos FEDER (PI18/01366, PI19/00815, PI19/00035, PI20/00744, PI21/00251, DTS18/00032), ERA-PerMed-JTC2018 (KIDNEY ATTACK AC18/00064, ISCIII-RETIC REDinREN RD16/0009), Sociedad Española de Nefrología, FRIAT, Comunidad de Madrid en Biomedicina B2017/BMD-3686 CIFRA2-CM, Fundacion ´ Canaria Instituto de Investigación Sanitaria de Canarias (FIISC), PIFUN05/18. Instituto de Salud Carlos III (ISCIII) RICORS program to RICORS2040 (RD21/0005/0001 and RD21/0005/0013) and SPACKDc PMP21/00109, FEDER funds, Cátedra Mundipharma-UAM of Diabetic Kidney Disease and Cátedra Astrazeneca-UAM of Chronic Kidney Disease and Electrolytes. J.D.C is recipient of a contract from Miguel Servet Programme (CP20/00122), ISCII