Invasion dynamics of the white piranha (Serrasalmus brandtii) in a Neotropical river basin
BIOLOGICAL INVASIONS
Authors: Teixeira, Daniel Fonseca; Neto, Francisco Ricardo Andrade; Gomes, Lais Carvalho; Beheregaray, Luciano Bellagamba; Carvalho, Daniel Cardoso
Abstract
Clarifying the intricate history of unrecorded fish invasions represents an important step in understanding the invasion process. Here, we elucidate the invasion of a Neotropical river basin in Southeastern Brazil by a very efficient predator, the white piranha (Serrasalmus brandtii). We used a temporal series of population dynamics data (2008-2016) and analyses of mitochondrial DNA sequences (COI, 16S, and control region) of specimens from the entire native (Sao Francisco River Basin, Southeastern Brazil) and invaded (Jequitinhonha River Basin, JRB) ranges. We detected low genetic diversity (h = 0.5835) and strong genetic structure in the invasive range (Fst = 0.9141), despite high genetic diversity (h = 0.8900) and low genetic structure (Fst from 0.0740 to 0.1348) in the native range. High genetic structure in the invaded range was associated with a hydroelectric dam that prevented the admixture of two independent introductory acts into the JRB (downstream and upstream of the Irape Dam). The rapid invasion capability of Serrasalmus brandtii, with few propagules, indicates that the species should be included in ecological risk assessments for restocking efforts of other commercially or ecologically important fish species and dam construction in Brazil. The combination of genetic and population dynamic datasets enabled the reconstruction of a top predator fish invasion in the Neotropics and shed light on ecological factors that influenced its invasion success.
Long-term maternal separation potentiates depressive-like behaviours and neuroinflammation in adult male C57/BL6J mice
PHARMACOLOGY BIOCHEMISTRY AND BEHAVIOR
Authors: Zhou, Lin; Wu, Zuotian; Wang, Gaohua; Xiao, Ling; Wang, Huiling; Sun, Limin; Xie, Yumeng
Abstract
Early life experience is closely related to depression caused by stress in adulthood. Early life experience, including maternal separation (MS), has been shown to evoke stress sensitivity to depression upon re-exposure to stress in adults. However, MS has also been shown to lead to resilience to stress-induced depression, which is contradictory and rarely studied. To investigate the effects of MS on depression in adults and the related mechanism, male C57/BL6J mouse pups were exposed to different MS procedures from postnatal day (PD)1 to PD21. Body weight (BW) measurements and behavioural tests (the forced swimming test (FST) and open field test (OFT)) were performed on PD41 to explore depressive and anxiety-like behaviours. Then, as adults, the mice were exposed to chronic unpredictable mild stress (CUMS) for 28 days, and then behavioural tasks were recorded. After CUMS exposure, the mice in the MS180 group (which were separated from their mothers for 3 h on PD1-PD21) showed significantly decreased time spent in the centre of the open field and reduced velocity in the OFT, a reduced latency to immobility in the FST, and decreased BW. However, the mice in the MS15 group (which were separated from their mothers for 15 min on PD1-PD21) performed similarly to NSNC mice (which were not separated from their mothers) in the behavioural tests. We further found that the expression of Ibal, a marker of neuroinflammation, was increased in the MS180 group but not in the MS15 group. In addition, our study showed decreased mRNA and protein expression of CRMP2, an important neuroprotective factor, in the MS180 group, but CRMP2 expression was unchanged in the MS15 group. This study confirmed the generation of different behavioural responses to stress exposure in adulthood due to different degrees of MS. Neuroinflammation and neuroprotection are involved, which requires further research.