Steroid hormones of the octopus self-destruct system

Stress Induced by Fishing in Common Octopus (Octopus vulgaris) and Relative Impact on Its Use as an Experimental Model

The common octopus (Octopus vulgaris), among coleoid cephalopods, has evolved the most complex nervous system and sophisticated behaviors. Historically, O. vulgaris was a key animal model for neurophysiology research, and today, it is studied for its genomic innovations. However, unlike other models, there is no octopus farming for research, so specimens must be collected from the wild. This study assessed the impact of fishing on octopuses used in research, considering those caught using artisanal pots in the 'Regno di Nettuno' Marine Protected Area, Ischia (NA). To evaluate fishing stress, we identified morphological stress indicators such as chromatophore pattern and posture, and three potential molecular markers, estrogen receptor (ER), catalase (CAT), and heat shock protein (HSP70). We measured the percentage of stress signals shown by fished specimens and analyzed their differential gene expression. The transcriptional levels of octopuses caught using traps were compared to control specimens acclimated in captivity. Results indicated fluctuations in gene expression due to fishing stress. These findings suggest that an acclimation period after the stress event of fishing is crucial for ensuring the welfare of octopuses used in research, thus enhancing the quality of physiological and ethological studies.

The circadian rhythm: A key variable in aging?

The determination of age-related transcriptional changes may contribute to the understanding of health and life expectancy. The broad application of results from age cohorts may have limitations. Altering sample sizes per time point or sex, using a single mouse strain or tissue, a limited number of replicates, or omitting the middle of life can bias the surveys. To achieve higher general validity and to identify less distinctive players, bulk RNA sequencing of a mouse cohort, including seven organs of two strains from both sexes of 5 ages, was performed. Machine learning by bootstrapped variable importance and selection methodology (Boruta) was used to identify common aging features where the circadian rhythms (CiR) transcripts appear as promising age markers in an unsupervised analysis. Pathways of 11 numerically analyzed local network clusters were affected and classified into four major gene expression profiles, whereby CiR and proteostasis candidates were particularly conspicuous with partially opposing changes. In a data-based interaction association network, the CiR-proteostasis axis occupies an exposed central position, highlighting its relevance. The computation of 11,830 individual transcript associations provides potential superordinate contributors, such as hormones, to age-related changes, as in CiR. In hormone-sensitive LNCaP cells, short-term supraphysiologic levels of the sex hormones dihydrotestosterone or estradiol increase the expression of the CiR transcript Bhlhe40 and the associated senescence regulator Cdkn2b (p15). According to these findings, the bilateral dysregulation of CiR appears as a fundamental protagonist of aging, whose transcripts could serve as a biological marker and its restoration as a therapeutic opportunity.

Hyperemesis gravidarum theories dispelled by recent research: a paradigm change for better care and outcomes

Nausea and vomiting (NVP) affect most pregnant women. At the severe end of the clinical spectrum, hyperemesis gravidarum (HG) can be life-threatening. The condition is fraught with misconceptions that have slowed progress and left women undertreated. Herein, recent scientific advances are presented that dispel common myths associated with HG related to maternal/offspring outcomes, etiology, and evolution. There is now strong evidence that (i) HG is associated with poor outcomes, (ii) a common cause of NVP and HG has been identified, and (iii) NVP is likely a protective evolutionary mechanism that occurs throughout the animal kingdom but is no longer necessary for human survival. Therefore, it is encouraging that we are finally on the cusp of testing treatments that may put an end to unnecessary suffering.

Living in a dynamic environment: The effects of multi-ways temperature variation on embryo and newborn juveniles of a shallow-water octopus (Amphioctopus fangsiao)

Shallow waters are characterized by fluctuating environmental conditions, modulating marine life cycles and biological phenomena. Multiple variations in water temperature could affect eggs and embryos during spawning events of many marine invertebrate species, yet most of the findings on embryonic development in invertebrates come from experiments based on the constant temperature. In this study, to examine the effects of temperature variation on octopus embryos, Amphioctopus fangsiao, a common shallow-water octopus along the coast of China, was exposed to the constant temperature (18 °C, in situ temperature of the seawater in Lianyungang), ramping temperatures (from 18 to 24 °C), diel oscillating temperatures (18 °C and 20 °C for 12 h each day), and acute increasing temperatures (the temperature increased sharply from 18 °C to 24 °C at embryonic development stage XIX) for 47 days (from embryogenesis to settlement). The results demonstrated that the temperature variations accelerated the development time of A. fangsiao embryos. Temperature fluctuations could cause embryonic oxidative damage and disorder of glycolipid metabolism, thereby affecting the growth performance of embryos and the survival rate of hatchings. Through transcriptome sequencing, the mechanistic adaption of the embryo to environmental temperature variations was revealed. The pathways involved in the TCA cycle, DNA replication and repair, protein synthesis, cell signaling, and nervous system damage repair were significantly enriched, indicating that the embryo could improve heat tolerance to thermal stress by regulating gene expression. Moreover, acute warming temperatures posed the most detrimental effects on A. fangsiao embryos, which could cause embryos to hatch prematurely from the vegetal pole, further reducing the survival of hatchings. Meanwhile, the diel oscillating temperature was observed to affect the normal morphology of the embryo, resulting in embryo deformities. Thus, the constant temperature is critical for balanced growth and defense status in octopuses by maintaining metabolism homeostasis. For the first time, this study evaluates the effects of multiple temperature fluctuations on embryos of A. fangsiao, providing new insights into the physiological changes and molecular responses of cephalopod embryos following dynamic temperature stress.

Signaling Ligand Heterogeneities in the Peduncle Complex of the Cephalopod Mollusc Octopus bimaculoides

INTRODUCTION

The octopus peduncle complex is an agglomeration of neural structures with remarkably diverse functional roles. The complex rests on the optic tract, between the optic lobe and the central brain, and comprises the peduncle lobe proper, the olfactory lobe, and the optic gland. The peduncle lobe regulates visuomotor behaviors, the optic glands control sexual maturation and maternal death, and the olfactory lobe is thought to receive input from the olfactory organ. Recent transcriptomic and metabolomic studies have identified candidate peptide and steroid ligands in the Octopus bimaculoides optic gland.

METHODS

With gene expression for these ligands and their biosynthetic enzymes, we show that optic gland neurochemistry extends beyond the traditional optic gland secretory tissue and into lobular territories.

RESULTS

A key finding is that the classically defined olfactory lobe is itself a heterogeneous territory and includes steroidogenic territories that overlap with cells expressing molluscan neuropeptides and the synthetic enzyme dopamine beta-hydroxylase.

CONCLUSION

Our study reveals the neurochemical landscape of the octopus peduncle complex, highlighting the unexpected overlap between traditionally defined regions.

Octopod Hox genes and cephalopod plesiomorphies

Few other invertebrates captivate our attention as cephalopods do. Octopods, cuttlefish, and squids amaze with their behavior and sophisticated body plans that belong to the most intriguing among mollusks. Little is, however, known about their body plan formation and the role of Hox genes. The latter homeobox genes pattern the anterior-posterior body axis and have only been studied in a single decapod species so far. Here, we study developmental Hox and ParaHox gene expression in Octopus vulgaris. Hox genes are expressed in a near-to-staggered fashion, among others in homologous organs of cephalopods such as the stellate ganglia, the arms, or funnel. As in other mollusks Hox1 is expressed in the nascent octopod shell rudiment. While ParaHox genes are expressed in an evolutionarily conserved fashion, Hox genes are also expressed in some body regions that are considered homologous among mollusks such as the cephalopod arms and funnel with the molluscan foot. We argue that cephalopod Hox genes are recruited to a lesser extent into the formation of non-related organ systems than previously thought and emphasize that despite all morphological innovations molecular data still reveal the ancestral molluscan heritage of cephalopods.

Steroid hormone signaling: What we can learn from insect models

Ecdysteroids are a group of steroid hormones in arthropods with pleiotropic functions throughout their life history. Ecdysteroid research in insects has made a significant contribution to our current understanding of steroid hormone signaling in metazoans, but how far can we extrapolate our findings in insects to other systems, such as mammals? In this chapter, we compare steroid hormone signaling in insects and mammals from multiple perspectives and discuss similarities and differences between the two lineages. We also highlight a few understudied areas and remaining questions of steroid hormone biology in metazoans and propose potential future research directions.

First known observations of brooding, development, and hatching of fertilized eggs for the North Pacific bigeye octopus, Octopus californicus

The North Pacific bigeye octopus, Octopus californicus (Berry, 1911) is a cold-water, deep-sea octopod. Little is known about their biology due to difficulty accessing their natural habitat and obtaining live specimens. Although they are a frequent bycatch product in commercial bottom trawl fisheries, individuals of this species have rarely been raised in captivity and their embryonic development has not yet been documented. Considering these limitations, we were fortunate to have witnessed this process leading to successful hatching in an aquarium setting. Here, we present a brief observational account of the first-known record of brooding, development, and hatching of fertilized eggs for O. californicus. The incubation time was a maximum of 10 months at a temperature between 8-10°C and embryos hatched over a period of 2.5 months. While more detailed research is needed, this preliminary information contributes to our limited knowledge of this species and supports life history theories of prolonged embryonic development under colder temperatures.