A specimen of Holocentrus adscensionis (Osbeck, 1765) was observed, photographed and filmed for several days in August 2022 in the shallow rocky zone of the WWF Miramare marine protected area near ...Trieste (Gulf of Trieste, northern Adriatic). This is the first record of this species in the Gulf of Trieste and in the Adriatic Sea, and the second in the Mediterranean Sea.
The original description of
Hatschekia exigua
Pearse, 1951 neglected innumerous features of taxonomic value as well as morphometric data and illustrations. Posteriorly, other author tried to access ...the type material, but their poor state of preservation compromised a detailed redescription. Since then, this species is in need for new morphological data, mainly from fresh material. In the present work, three specimens of
Holocentrus adscensionis
from Mucuripe Bay, Fortaleza, State of Ceará, Northeastern Brazil, were parasitized by copepods on their gills. Parasites were fixed and preserved in 80% ethanol and cleared in 85% lactic acid for morphological observations using light microscopy. The females were identified as
Hatschekia exigua
by the cephalothorax representing about one-fourth of total body length, with lateral margins expanded into lateral lobes, first exopod with basal segment armed with one outer setae and terminal segment with three setae, first endopod with basal segment unarmed and terminal segment with five setae, leg 3 reduced to two setae and leg 4 reduced to single seta. Comparison with the type series revealed morphological differences in trunk and small appendages, which may be related to alterations in the specimens, caused by the mounting methodology and poor preservation. A detailed morphological analysis of the male revealed for the first time that they differ from their closest congeners by having five setae on the last endopodal segment of leg 1, by smooth intercoxal sclerites on legs 1 and 2 and by a proximolateral process on the third segment of antenna. Moreover, this work represents the first report of
H. exigua
in Brazil and the first hatschekiid copepod found off the coast of Ceará, highlighting that the diversity of Hatschekiidae in this oceanographic region still needs further investigation.
On tropical reefs, cleaning interactions, in which a fish or shrimp cleaner removes ectoparasites from a client fish, are common. Such cleaning interactions have been shown to reduce physiological ...stress in the clients. We asked whether the process of cleaning by a cleaner wrasse Thalassoma noronhanun modified a fish client's risk assessment, hypothesizing that the benefits of being cleaned may modify the cost avoiding a potential disturbance or predator. We experimentally approached fish of two species (a parrotfish Sparisoma amplum and a squirrelfish Holocentrus adscensionis) when they were being cleaned and when they were not being cleaned, and measured the client's flight initiation distance (FID) – a metric of risk assessment. Both client fish species tolerated ~30% closer approach when being cleaned. The body size of the client did not affect FID in either species, and the number of cleaners present did not influence FID of squirrelfish, but parrotfish who received cleaning from two cleaners had longer FID. These findings imply that fish being cleaned modify their risk assessment, and these results add to a list of potential costs fish clients face in this fascinating mutualism.
On tropical reefs, cleaning interactions in which a fish or shrimp cleaner removes ectoparasites from a client fish are common. Such cleaning interactions have been shown to reduce physiological stress in the clients. We asked whether the process of cleaning by a cleaner wrasse modified a fish client's risk assessment. We experimentally approached fish when they were being cleaned and when they were not being cleaned, and measured the client's flight initiation distance. Both client fish species tolerated ~30% closer approach when being cleaned. These findings imply that fish being cleaned modify their risk assessment.
The record of articulated marine fish fossils during the latest Cretaceous and earliest Cenozoic is sparse. The oldest-known definitive squirrelfishes and soldierfishes, like the first examples of ...many extant reef-dwelling clades, are known from early Eocene deposits of Europe. Here, we describe a new genus and species of holocentroid (Teleostei: Beryciformes: Holocentroidea) based on material from three individuals from early Paleocene (Danian) deposits of New Jersey, USA using micro-computed tomography. The specimens comprise a three-dimensionally preserved skull and partial postcranium, plus two isolated neurocrania. The new taxon, †Iridopristis parrisi, possesses a unique combination of characters, including a heterosulcoid otolith morphology and an edentulous premaxillary tooth-gap, while lacking a newly proposed character for the remainder of Cenozoic holocentroids: a lamina on the lateral surface of the anguloarticular, anterior to the jaw joint. Bayesian phylogenetic analysis of morphological, stratigraphical and molecular data under the fossilized birth-death process finds that the new taxon branches from the holocentrid stem, where it is joined by two of the three squirrelfish genera from the early Eocene (Ypresian) of Bolca, Italy. We estimate a Danian divergence between Myripristinae and Holocentrinae, the two reciprocally monophyletic subfamilies of Holocentridae. Our analysis suggests that several holocentroid lineages crossed the Cretaceous-Palaeogene boundary.
http://zoobank.org/urn:lsid:zoobank.org:pub:0B458336-EFCF-46D0-98D0-CE5AD371D7AF
Summary
The southeastern coast of Florida, USA supports a substantial recreational fishery, yet little is known of the coral reef ecosystem or fisheries resources past 50 m depth. Fish assemblages ...associated with low‐relief substrate and three vessel reefs between 50 and 120 m depth off southeast Florida were surveyed by remotely operated vehicles providing the first characterization of the mesophotic fish assemblages in the region. Two distinct assemblages were observed on low‐relief substrate and high‐relief vessel reefs. A total of 560 fishes of 42 species was recorded on 27 dives on low‐relief substrate, and 50 152 fishes of 65 species were recorded on 24 dives on three vessel reefs. Small planktivorous Anthiinae fishes and several economically valuable species were common on vessel reefs but rare on low‐relief substrate. Fish assemblages on vessel reefs more closely resembled those found at similar depths in high‐relief natural areas off east‐central Florida and the Gulf of Mexico than those associated with adjacent low‐relief habitat or nearby coral reef tracts. From a fisheries perspective, these results provide limited support to the hypothesis that in deep‐water regions with limited relief, vessel reefs may provide an opportunity to increase fish diversity and abundance by creating high‐relief habitat without compromising adjacent fish assemblages.
The community structure of the reef fish fauna of Trindade Island, a volcanic oceanic island located 1160 km off the coast of Brazil, is described based on intensive visual censuses. Seventy‐six ...species were encountered in 252 censuses, with mean ±s.e. of 99 ± 3 individuals and 15·7 ± 0·3 species 40 m−2 transect. The average fish biomass, calculated from length‐class estimation, was 22·1 kg40m−2 transect. The species contributing most to biomass were, in decreasing order, Melichthys niger, Cephalopholis fulva, Kyphosus spp., Holocentrus adscensionis, Sparisoma amplum, Sparisoma axillare, Acanthurus bahianus and Epinephelus adscensionis. Carnivorous fishes were the largest trophic group in terms of biomass, followed by omnivores and roving herbivores. The two predominant types of reef habitat, fringing reefs built by coralline algae and rocky reefs made of volcanic boulders, showed significant differences in the biomass and the abundance of the trophic guilds. Within each habitat type, significant differences in species richness, density and biomass were detected among crest, slope and interface zones. Although similar in overall species composition to coastal reefs in Brazil, the fish fauna of Trindade Island shares certain characteristics, such as a high abundance of planktivores, with other Brazilian oceanic islands. Despite comparatively high fish biomass, including the macro‐carnivorous species habitually targeted by fisheries, signs of overfishing were evident. These findings highlight the urgency for a conservation initiative for this isolated, unique and vulnerable reef system.
The hyperaccumulation of trace elements is a widely characterized phenomenon in plants, bacteria, and fungi, but has received little attention in animals. However, there are numerous examples of ...animals that specifically and facultatively accumulate trace elements in the absence of elevated environmental concentrations. Metal hyperaccumulating animals are usually marine invertebrates, likely owing to environmental (e.g. constant exposure via the water) and physiological (e.g. osmoconforming and reduced integument permeability) factors. However, there are examples of terrestrial animals (insect larvae) and marine vertebrates (e.g. squirrelfish) that accumulate high body and/or tissue metal burdens. This review examines examples of animal hyperaccumulation of the elements arsenic, copper, iron, titanium, vanadium and zinc, describing mechanisms by which accumulation occurs and, where possible, hypothesizing functional roles. Groups such as the ascidians (sea squirts), molluscs (gastropods, bivalves and cephalopods) and polychaete annelids feature prominently as animals with hyperaccumulating capacity. Many of these species are potential model organisms offering insight into fundamental processes underlying metal handling, with relevance to human disease and aquatic metal toxicity, and some offer promise in applied fields such as bioremediation.
In the present work, specimens of Holocentrus adscensionis, caught off Pernambuco State, northeast Brazil, by small scale artisanal fishing boats, were analyzed with regard to gonad maturation, gonad ...index, size at first sexual maturity, fecundity, type and time of spawning. Two hundred and three specimens were randomly collected, 102 males and 101 females, resulting in a sex ratio very close to 1:1. Size at first sexual maturity was estimated at 14.6 cm fork length, which is smaller than the most caught size class. Females in final maturation were only recorded from October to March, while the proportion of resting females was the highest in June and July. The seasonal variation of sexual stages, together with the variation of the monthly mean gonad index, with the lowest values for females being recorded from May to July, suggests lower sexual activity for this species during this period of the year, which coincides with winter time. The pattern of ovarian development indicates that spawning is synchronous, with oocytes ripening in more than two groups. It is therefore characterized as a batch spawning. Absolute fecundity ranged from 56274 to 249863 oocytes.
Resistance to traditional antifungal drugs has increased significantly over the past three decades, making identification of novel antifungal agents and new targets an emerging priority. Based on the ...extraordinary zinc requirement of several fungal pathogens and their well-established sensitivity to zinc deprivation, we developed an efficient cell-based screen to identify new antifungal drugs that target the zinc homeostasis machinery. The screen is based on the zinc-regulated transcription factor Zap1 of Saccharomyces cerevisiae, which regulates transcription of genes like the high-affinity zinc transporter ZRT1. We generated a genetically modified strain of S. cerevisae that reports intracellular zinc deficiency by placing the coding sequence of green fluorescent protein (GFP) under the control of the Zap1-regulated ZRT1 promoter. After showing that the GFP fluorescence signal correlates with low intracellular zinc concentrations in this strain, a protocol was developed for screening small-molecule libraries for compounds that induce Zap1-dependent GFP expression. Comparison of control compounds and known modulators of metal metabolism from the library reveals a robust screen (Z' = 0.74) and validates this approach to the discovery of new classes of antifungal compounds that interfere with the intracellular zinc homeostasis. Given that growth of many pathogenic organisms is significantly impaired by zinc limitation; these results identify new types of antifungal drugs that target critical nutrient acquisition pathways.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Female squirrelfish (Fam. Holocentridae) can accumulate and temporarily sequester copious amounts of zinc (Zn) in their livers. There, it is initially compartmentalized before a subsequent, ...estrogen-triggered redistribution to the ovaries. Here we show that cellular uptake of Zn is also influenced by estrogen signaling, and that estrogen increases concentrations of the plasma Zn-binding protein vitellogenin (VTG). However, estrogen-mediated increases in VTG are not sufficient to accommodate the magnitude of hepato-ovarian Zn transfer in female squirrelfish (Holocentrus adscensionis). These findings suggest that holocentrids have acquired the ability to use hormonal cues to drive hepatic uptake and storage of Zn, signal for its physiological redistribution, and influence the capacity for systemic transport of Zn beyond the mediation of increased plasma VTG concentrations. Such specific adaptations suggest an advantage for the oocyte, which is corroborated in further studies where we determined that oocyte Zn concentrations are positively correlated with egg viability in captive-spawned squirrelfish. The novel nature of these findings underlies the importance of Zn in squirrelfish reproductive biology.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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