Lenga natural forest : volumetric assessment of shelterwood felling

Se realizó una corta de protección suave en un bosque natural de lenga, ubicado en la isla de Tierra del Fuego. Ésta consistió en extraer aproximadamente el 30 % del área basal original, en una superficie de 10 ha. Se establecieron cuatro parcelas de inventario (20 x 50 m), distribuidas en forma sistemática. En ellas se identificaron y midieron todos los árboles. Luego de efectuada la corta, se midieron las trozas obtenidas de los árboles volteados y se calificaron en aserrables, astillables o desecho. El bosque presentó originalmente un área basimétrica de 71,6 m 2/ha y un volumen total de 899,6 m 3/ha. Producto de la corta se obtienen 251,4 m 3/ha, de los cuales 90,2 m 3 /ha son aserrables; 98,5 m 3/ha astillables y 62,8 m 3/ha de desecho.A protection felling test was established in a lenga site located in Tierra del Fuego. The test consisted of applying a felling, by extracting 30 % of the original basal area of 10 ha. Four forest inventory plots (20 x 50 m), distributed in a systematic manner were established. Trees within these plots were identified and measured. The selected trees were then marked to form the protection canopy. After the felling, each of the logs obtained from the felled trees were measured, and clasified as sawlogs, logs for chips and waste logs. The forest, originally presented a basal area of 71.6 m²/ha, and a total volume of 899.6 m 3/ha. W ith the protection felling 251.4 m3/ha were obtained, of wich 90.2 m 3/ha corresponded to saw logs, 98.5 m 3/ha to logs from chips, and 62.8 m 3/ha  of waste logs.Fil: Donoso, Sergio. Universidad de Chile. Facultad de Ciencias Agronómicas.Fil: Caldentey, Juan. Universidad de Chile. Facultad de Ciencias Agronómicas.Fil: Garib, Igor. Universidad de Chile. Facultad de Ciencias Agronómicas

Mutations in the endothelin receptor type A cause mandibulofacial dysostosis with alopecia

The endothelin receptor type A (EDNRA) signaling pathway is essential for the establishment of mandibular identity during development of the first pharyngeal arch. We report four unrelated individuals with the syndrome mandibulofacial dysostosis with alopecia (MFDA) who have de novo missense variants in EDNRA. Three of the four individuals have the same substitution, p.Tyr129Phe. Tyr129 is known to determine the selective affinity of EDNRA for endothelin 1 (EDN1), its major physiological ligand, and the p.Tyr129Phe variant increases the affinity of the receptor for EDN3, its non-preferred ligand, by two orders of magnitude. The fourth individual has a somatic mosaic substitution, p.Glu303Lys, and was previously described as having Johnson-McMillin syndrome. The zygomatic arch of individuals with MFDA resembles that of mice in which EDNRA is ectopically activated in the maxillary prominence, resulting in a maxillary to mandibular transformation, suggesting that the p.Tyr129Phe variant causes an EDNRA gain of function in the developing upper jaw. Our in vitro and in vivo assays suggested complex, context-dependent effects of the EDNRA variants on downstream signaling. Our findings highlight the importance of finely tuned regulation of EDNRA signaling during human craniofacial development and suggest that modification of endothelin receptor-ligand specificity was a key step in the evolution of vertebrate jaws