Dissecting embryonic and extra-embryonic lineage crosstalk with stem cell co-culture.

Faithful embryogenesis requires precise coordination between embryonic and extraembryonic tissues. Although stem cells from embryonic and extraembryonic origins have been generated for several mammalian species(Bogliotti et al., 2018; Choi et al., 2019; Cui et al., 2019; Evans and Kaufman, 1981; Kunath et al., 2005; Li et al., 2008; Martin, 1981; Okae et al., 2018; Tanaka et al., 1998; Thomson et al., 1998; Vandevoort et al., 2007; Vilarino et al., 2020; Yu et al., 2021b; Zhong et al., 2018), they are grown in different culture conditions with diverse media composition, which makes it difficult to study cross-lineage communication. Here, by using the same culture condition that activates FGF, TGF-ß and WNT signaling pathways, we derived stable embryonic stem cells (ESCs), extraembryonic endoderm stem cells (XENs) and trophoblast stem cells (TSCs) from all three founding tissues of mouse and cynomolgus monkey blastocysts. This allowed us to establish embryonic and extraembryonic stem cell co-cultures to dissect lineage crosstalk during early mammalian development. Co-cultures of ESCs and XENs uncovered a conserved and previously unrecognized growth inhibition of pluripotent cells by extraembryonic endoderm cells, which is in part mediated through extracellular matrix signaling. Our study unveils a more universal state of stem cell self-renewal stabilized by activation, as opposed to inhibition, of developmental signaling pathways. The embryonic and extraembryonic stem cell co-culture strategy developed here will open new avenues for creating more faithful embryo models and developing more developmentally relevant differentiation protocols.

Taxonomic information on some Japanese Chironomidae (Diptera) described by Dr. M. Sasa (†).

Holotypes of 19 species and non-type specimens preserved in the Sasa collection at The National Museum of Science, Tokyo, Japan, have been examined. Seventeen new synonyms are given, as follows: Paratrissocladius ogasaduodecimus Sasa et Suzuki, 1997 = Paraphaenocladius impensus (Walker, 1856); Bryophaenocladius togafelix Sasa et Okazawa, 1992, and B. toganitemus Sasa et Okazawa, 1992 = Pseudorthocladius togakileus Sasa et Okazawa, 1992; Bryophaenocladius togatenuis Sasa et Okazawa, 1992 of Smittia nudipennis (Goetghebuer, 1913); Chironomus daitoefeus Sasa et Suzuki, 2001 of C. circumdatus Kieffer, 1916; C. inaabeus Sasa, Kitami et Suzuki, 2001 = C. nippodorsalis Sasa, 1979; C. tokarabeceus Sasa et Suzuki, 1995 = C. okinawanus Hasegawa et Sasa, 1987; C. ginzanbeceus Sasa et Suzuki, 2001 = C. riparius Meigen, 1904; C. simantobeceus Sasa , Suzuki et Sakai, 1998 = C. claggi Tokunaga, 1964; C. echizensis Sasa, 1994 = C. yoshimatsui Martin et Sublette, 1972; Chironomus famiabeus Sasa, 1996, C. inabeceus Sasa, Kitami et Suzuki, 2001 and C. ginzanabeus Sasa et Suzuki, 2001 = Glyptotendipes biwasecundus Sasa et Kawai, 1987; Chironomus kagaensis Sasa, 1994 = Glyptotendipes tokunagai Sasa, 1979; Chironomus toyamabiceus Sasa, 1996 = Kiefferulus umbraticola Yamamoto, 1979; Microtendipes iriocedeus Sasa et Suzuki, 2000 of Polypedilum bingoparadoxum Kawai, Inoue et Imabayashi , 1998. The sufficient reason why Chironomus daitocedeus Sasa et Suzuki, 2001 should be treated as a junior synonym of C. javanus Kieffer, 1924 is shown. Two further species: Paratrissocladius sudagaicedeus Sasa et Tanaka, 2001 and Bryophaenocladius togatenellus Sasa et Okazawa, 1992 are transferred to Chaetocladius. Specimens from Okinawa, Miyako and Ishigaki Islands, originally reported as Rheocricotopus chalybeatus (Edwards, 1929) are identified as R. okifoveatus Sasa, 1990. A new species, Einfeldia sasai is described on the basis of specimens recorded from Minamidato Island, previously incorrectly determined as E. pagana.

Validez de cuatro análisis de dentición mixta en una muestra de niños colombianos y selección de variables que puedan mejorarlos / Validation of four mixed dentition analysis in a group of Colombian children and selected variables that can improve these methods

La precisión de los métodos de Tanaka y Johnston, Staley y Hoag (1978), Staley, Shelly y Martín (1979) Staley y Col (1984), Ingervall y Lennartson y Hixson-Oldfather fue aprobada en una muestra de 43 individuos colombianos. Las predicciones para cada análisis fueron realizadas en modelos y radiografías en dentición mixta y sus resultados corroborados con el tamaño real de canino y bicúspides de los mismos sujetos en dentición permanente. Para analizar las diferencias se emplearon el coeficiente de correlación de Pearson entre los valores predicho y real, el promedio de la diferencia entre el valor real y predicho y su desviación estándar. Las correlaciones mas altas en el maxilar superior se observaron en los métodos de Staley y Col (1978 y 1984) y la mas baja para el análisis de Tanaka y Johnston. En el maxilar inferior se observaron valores más altos que el maxilar superior y las mejores correlaciones fueron para los análisis de Staley y Col (1979 y 1984) y las mas baja para el de Tanaka y Johnston. Todos los análisis estudiados mostraron mas error al ser aplicados en la muestra colombiana que el que sus autores reportaron. La variabilidad del error fue entre un 13 por ciento y un 42 por ciento. Además variados grados de sobre o subestimación se encontraron dependiendo del análisis. Por medio de análisis de regresión a pasos se desarrollaron ecuaciones de regresión para predecir el tamaño mesodistal del canino y premolares permanentes no erupcionados.