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The Dianchi golden-line barbel, Sinocyclocheilus grahami (Regan, 1904), is one of the “Four Famous Fishes” of Yunnan Province, China. Given its economic value, this species has been artificially bred successfully since 2007, with a nationally selected breed (“S. grahami, Bayou No. 1”) certified in 2018. For the future utilization of this species, its growth rate, disease resistance, and wild adaptability need to be improved, which could be achieved with the help of molecular marker-assisted selection (MAS). In the current study, we constructed the first chromosome-level genome of S. grahami, assembled 48 pseudo-chromosomes, and obtained a genome assembly of 1.49 Gb. We also performed QTL-seq analysis of S. grahami using the highest and lowest bulks (i.e., largest and smallest size) in both a sibling and random population. We screened two quantitative trait loci (QTLs) (Chr3, 14.9–39.1 Mb and Chr17, 4.1–27.4 Mb) as the major growth-related locations. Several candidate genes (e.g., map2k5, stat1, phf21a, sox6, and smad6) were also identified, with functions related to growth, such as cell differentiation, neuronal development, skeletal muscle development, chondrogenesis, and immunity. These results built a solid foundation for in-depth MAS studies on the growth traits of S. grahami.

A new species of the genus Atelopus, Atelopus fronterizo   sp. nov.  , from eastern Panama is described herein based on molecular, morphological, and bioacoustic evidence. The new species can be distinguished from its congeners occurring in the region by a combination of the following characters: (1) phalangeal reduction in thumb; (2) SVL (females only) (35.1–50.1; n=13), HW/SVL (0.23–0.34; n=59), EYND/HW (0.27–0.39; n=60), TIBL/SVL (0.41–0.56; n=58), and HAL/SVL (0.22–0.28; n=49); (3) dorsal color pattern with green or yellow background and extensive dark olive blotches forming transversal bands or mottling; (4) advertisement call duration 176–235 ms with 19–34 pulses, average pulse rate 131.69 pulses/s, and dominant frequency 2 422.50–2 606.50 Hz. The new species is nested within the Central American clade of Atelopus. The minimum Kimura‐2‐parameter (K2P) genetic divergence between Atelopus fronterizo   sp. nov.   and its most phylogenetically similar congeners (A. certus and A. glyphus) is >2.6% for 16S and >4.9% for COI (

Table 1

). The phylogenetic relationship is strongly supported by ultrafast bootstrap values for the maximum-likelihood trees of both genetic markers (16S, 96; COI, 100,

Figure 1A

). Bayesian analysis of the concatenated sequences resulted in a tree with similar topology and high posterior probability support (0.99; Supplementary Figure S1). In addition, haplotype networks inferred from COI and 16S (Supplementary Figure S2) showed a well-separated clade containing the new species (two for COI, four for 16S). The number of mutational steps between haplotypes for the new species samples is very low (1–4 in 16S; one in COI), and the minimum number of mutational steps from the nearest species is nine for 16S (distance to A. certus) and 28 for COI (distance to A. glyphus).

Review
Parabiosis is a surgical method of animal modeling with a long history. It has been widely used in medical research, particularly in the fields of aging, stem cells, neuroscience, and immunity in the past two decades. The protocols for parabiosis have been improved many times and are now widely accepted. However, researchers need to consider many details, from surgical operation to perioperative management, to reduce mortality and maintain the parabiosis union. Although parabiosis has certain inevitable limitations, it still has broad application prospects as an irreplaceable animal model in the medical research field.