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The relationship between water temperature and gonadal maturation of a landlocked ecophenotype of marine pejerrey (Odontesthes argentinensis) in La Salada de Pedro Luro lake was analysed during three spawning seasons. Mainly vitellogenic females were found in August (winter), some ovulating in October (mid-spring) and with atretic oocytes in December (end of spring). In accordance with this, gonadosomatic index (GSI) and estradiol plasma levels showed maximum values in October (7.6 ± 0.7%; 1631.7 ± 256.1 pg/mL) and minimum values in December (1.2 ± 0.3%; 230,33 ± 8,74 pg/mL). Spermiating males were found during the whole spawning season and only arrested in December. The highest GSI values were recorded in October (4.6 ± 0.2%) and for testosterone (T) in August (1113.2 ± 503.8 pg/mL). Meanwhile, in December the minimum GSI and T plasma values (1.3 ± 0.6%, 323.8 ± 5.3 pg/mL) were observed. According to the Fourier fitted models, temperature explains more than 70% of the observed variation in GSI in both sexes. Moreover, the total GSI variation range was positively related to the total temperature range variation experienced during the reproductive seasons demonstrating the influence of this environmental variable on maturation intensity and dynamics. [ABSTRACT FROM AUTHOR]

In this study, the complete mitochondrial genome ofOdontesthessp. has been studied first. The genome is 16,528 bp in length and contains 13 protein-coding genes, 22 tRNA genes, 2 ribosomal RNA genes and 1 putative control region. The mitochondrial genome ofOdontesthessp. had common features about gene arrangement and tRNA structures compared with those of other teleost fishes. The overall base composition ofOdontesthessp. is T 27.3%, C 29.4%, A 26.0% and G 17.3%, with a slight A + T bias of 53.3%. Meanwhile, the conserved motif 5′-GCCGG-3′ was determined in the origin of light-strand replication ofOdontesthessp. The mitochondrial genome of this species would play an important role in the phylogenetics of Atherinopsidae. [ABSTRACT FROM PUBLISHER]

The shortfin silversideChirostoma humboldtianum, is an endemic fish from the Mesa Central of Mexico, it is considered the “ancestral” species of the “peces blancos” and plays an important role as a potential species for aquaculture.Here we sequence its mitogenome (Genbank accession number KJ921739), which has a total length of 16,447 bp, and the arrangement consist of 13 protein-coding genes, 2 ribosomal RNA (rRNA) genes and 22 transfer RNA similar to other Atheriniformes. This mitogenome will be useful for phylogenetic, population and phylogeographic studies of this and other important atherinopsid species. [ABSTRACT FROM AUTHOR]

The complete sequence of the mitochondrial genome for the Chilean silversideBasilichthys microlepidotusis reported for the first time. The entire mitochondrial genome was 16,544 bp in length (GenBank accession no. KM245937); gene composition and arrangement was conformed to that reported for most fishes and contained the typical structure of 2 rRNAs, 13 protein-coding genes, 22 tRNAs and a non-coding region. The assembled mitogenome was validated against sequences of COI and Control Region previously sequenced in our lab, functional genes from RNA-Seq data for the same species and the mitogenome of two other atherinopsid species available in Genbank. [ABSTRACT FROM AUTHOR]