ASPEK BIOLOGIS IKAN EKOR PEDANG (Xiphophorus hellerii HECKEL, 1848) DI CATUR DANAU BALI

Ikan ekor pedang (Xiphophorus hellerii) merupakan jenis ikan asing yang mendiami catur danau Bali (Danau Tamblingan, Danau Buyan, Danau Bratan dan Danau Batur). Tujuan penelitian ini adalah untuk mengungkapkan nisbah kelamin, pola pertumbuhan dan kondisi ikan ekor pedang di catur danau Bali. Nisbah kelamin ikan ekor pedang di keempat danau berada dalam keadaan tidak seimbang. Proporsi ikan jantan di Danau Tamblingan, Danau Beratan dan Danau Batur lebih banyak daripada ikan betina dan kondisi sebaliknya ditemukan di Danau Buyan. Pola pertumbuhan ikan jantan di catur danau Bali adalah alometrik negatif dan ikan betina menunjukkan pola pertumbuhan alometrik negatif di Danau Tamblingan dan Danau Beratan dan pola pertumbuhan isometrik di Danau Buyan dan Danau Batur. Spesies ikan ini berada dalam kondisi baik di catur danau Bali dengan nilai faktor kondisi berkisar antara 0,47–1,54 dengan rerata 0,92 untuk ikan jantan dan 0,43–2,94 dengan rerata 1,12 untuk ikan betina.

Xmrks the Spot: Fish Models for Investigating Epidermal Growth Factor Receptor Signaling in Cancer Research

Studies conducted in several fish species, e.g., Xiphophorus hellerii (green swordtail) and Xiphophorus maculatus (southern platyfish) crosses, Oryzias latipes (medaka), and Danio rerio (zebrafish), have identified an oncogenic role for the receptor tyrosine kinase, Xmrk, a gene product closely related to the human epidermal growth factor receptor (EGFR), which is associated with a wide variety of pathological conditions, including cancer. Comparative analyses of Xmrk and EGFR signal transduction in melanoma have shown that both utilize STAT5 signaling to regulate apoptosis and cell proliferation, PI3K to modulate apoptosis, FAK to control migration, and the Ras/Raf/MEK/MAPK pathway to regulate cell survival, proliferation, and differentiation. Further, Xmrk and EGFR may also modulate similar chemokine, extracellular matrix, oxidative stress, and microRNA signaling pathways in melanoma. In hepatocellular carcinoma (HCC), Xmrk and EGFR signaling utilize STAT5 to regulate cell proliferation, and Xmrk may signal through PI3K and FasR to modulate apoptosis. At the same time, both activate the Ras/Raf/MEK/MAPK pathway to regulate cell proliferation and E-cadherin signaling. Xmrk models of melanoma have shown that inhibitors of PI3K and MEK have an anti-cancer effect, and in HCC, that the steroidal drug, adrenosterone, can prevent metastasis and recover E-cadherin expression, suggesting that fish Xmrk models can exploit similarities with EGFR signal transduction to identify and study new chemotherapeutic drugs.

The determination of oxidative damage caused by fluoxetine hydrocloride in swordtail fish (Xiphophorus hellerii)

In this study, it was aimed to determine the oxidative stress in the tissues of the swordtail fish (Xiphophorus hellerii Heckel, 1848) after exposed to the active ingredient of Prozac® and one of the SSRI (Selective Serotonine Reuptake Inhibitor) group antidepressants, Fluoxetine Hydrochloride, which is considered to be safe cardiovascular. It is widely used in the treatment of depression, which is one of the increasing health problems in the World. Fluoxetine-HCl has been found 0.012 μg/L in surface waters and in the dose range of 0.54-0.929 μg/L in wastewater (Sehonova et al., 2018). In line with this information, 0.1 μg / L and 1 μg / L Fluoxetine-HCl was administered to swordtails. At the end of 96 hours, heart and liver tissues of the fish were dissected under antiseptic conditions and homogenized. Later, malondialdehyde (MDA), total glutathione (GSH), catalase (CAT) enzyme activity, superoxide dismutase (SOD) enzyme activity and total protein amount were determined by spectrophotometric methods. As a result, while CAT enzyme activity and MDA level decreased in heart tissue, SOD enzyme activity and GSH level increased. In liver tissue, while CAT enzyme activity and GSH amount increased, SOD enzyme activity and MDA level decreased. As a result of the comparisons with the control group, it was determined that Fluoxetine-HCl is effective in regulating the stress response by affecting the stress pathways in swordtails.

First confirmed record of an established population of green swordtail (Xiphophorus hellerii Heckel, 1848) in Europe

The green swordtail (Xiphophorus hellerii) is a freshwater and brackish water fish native to North and Central America. It experiences wide human-traced introduction around the world, mostly due to aquarium release. Individuals of the green swordtail population from the warm spring with artificial origin located in Asparuhovo district, Bulgaria, were collected. The invasiveness screening tool for non-native freshwater fishes (FISK v2) calibrated for the Balkan region was used to assess potential invasion risk of the green swordtail to the coastal freshwater bodies of the Eastern Balkans. This study is the first confirmation on an existing self-sustained population of X. hellerii in Bulgaria and respectively in Europe. Climate change and the trend of warmer winters are prerequisites for the acclimatization of this species to the temperature out of the studied thermal spring. Therefore, the potential of the green swordtail to colonise new habitats is increasing with such facilitated acclimatization. We conclude that the green swordtail poses a high risk to become the next new invasive species in Southern Europe.

Rheotaxis Response Based on Sexual Dimorphism in the Green Swordtail Fish, Xiphophorus hellerii

Morphological distinctions between males and females of a species are referred to by sexual dimorphism. It may result from various selection pressures affecting either sex or both and may occur in any dioecious species, including Green Swordtail fish, which are sexually reproductive. This study examined the different rheotaxis responses of Xiphophorus hellerii based on different sexes and morphological features. We analyzed ten adult males, ten gravid females, and ten non-gravid females of Xiphophorus helleri collected down the river and transferred into the column. We counted the number of the individual that performed positive rheotaxis (+), negative rheotaxis (-), and indifference response (0). The result showed different rheotaxis responses shown by male, non-gravid female, and gravid female X. hellerii. The highest percentage of positive rheotaxis response (movement against the current) was shown by non-gravid female X. hellerii, reaching up to 89%. Morphological differences between male, non-gravid female, and gravid female X. hellerii appear to affect the orientation and ability of X. hellerii in giving response against current and certainly has an impact on their survival in nature.