Gross lesions in the Hubb octopus Octopus hubbsorum

A visible pathological condition located in the arms and mantle of the Hubb octopus Octopus hubbsorum from the Northeast Pacific waters is described for the first time. Histological sections confirmed later stages (fibrosis) of a chronic inflammatory condition of unknown aetiology.     

Reproductive traits of the small Patagonian octopus Octopus tehuelchus

This study evaluated the reproductive features of Octopus tehuelchus in three coastal environments of San Matías Gulf (Patagonia). Monthly samples of O. tehuelchus were used to estimate size at maturity, compare seasonal changes in oocyte size frequency distributions between sites as well as oocyte number and size between female maturity stage and sites. Females in Islote Lobos had a smaller size at maturity than females in San Antonio Bay and El Fuerte, probably as a consequence of a generally smaller body size. Males in San Antonio Bay were smaller at maturity than females. O. tehuelchus is a simultaneous terminal spawner. Fecundity (expressed as number of vitellogenic oocytes in ovary) was lower in Islote Lobos, and an increase in oocyte number in relation to female total weight was found. Females in San Antonio Bay had the largest oocytes, which may indicate higher energy reserves for the embryo and therefore higher juvenile survival. There was a close relationship between reproduction, growth and condition, represented as size at maturity, number and size of vitellogenic oocytes and period of maturity and spawning. Given the local variation in some reproductive features of O. tehuelchus, studies should focus on the environmental factors, which bring about this variation, and on how it affects the dynamics of local populations.     

Life history and distribution of the small south-western Atlantic octopus, Octopus tehuelchus

Although this species has been reported from shallow waters down to 90 m depth, knowledge is almost entirely based on intertidal samples. In this study both intertidal and subtidal samples were taken during 1982–1987, in northern San Matias Gulf (41° S, 63° 30' W). This is a large-egged (eggs: 9–12 mm long ×–5 mm wide, stack of 4–6 mm long) and small-sized (up to 150 g) octopus. Egg laying occurs between autumn and winter. Embryonic development takes about four months (water temperature:–19°C). Large hatchlings (DML: 5·64 mm, TL: 14·23 mm, TW: 0·139 g) emerge over spring and early summer, and development is direct. Maximum size is reached after 17–18 months; mating takes place in summer. Females reduce their feeding activity when they reach maturity, and cease eating while brooding. Mean life-span is two years, but some individuals (mostly females) may live up to three years. Females approaching the beginning of the brooding period move to the subtidal zone, where males outnumber females until the end of summer and females (mostly brooders) then outnumber males. In the intertidal zone sex ratio was 1:1 from December to late March, but in April males outnumber females.
These life-history traits are compared with those of other large-egged octopuses and are discussed in relation to environmental conditions prevailing in the San Matias Gulf.     

Movement, injuries and growth of members of a natural population of the Pacific pygmy octopus, Octopus digueti

Sampling inadequacies and an inability to distinguish age classes have limited our knowledge of octopus biology in nature. Using an artificial shelter sampling technique (Voight, 1988 a ), and defining mature males by the presence of enlarged suckers (Voight, In press), an intertidal population of Octopus digueti was monitored for one year.
In total, 803 octopuses were narcotized; the mass, sex, arm injuries and reproductive condition of each octopus were recorded. Captures were more frequent in lower intertidal areas offering higher shelter availability and a more moderate environment. Capture rates, assumed to indicate octopus movement, correlated with sea temperature except during full moon periods when they were reduced. Over 26%, of the octopuses handled had damaged arms or arm tips, with dorsal arm pairs more often injured. The overall sex ratio was significantly male biased, probably due to maturity-linked mobility differences between the sexes.
Reproduction occurred throughout the year; reproductively competent adults, brooding females and juveniles were present every month. However, annual temperature oscillations synchronize spring hatching of eggs spawned from winter to early spring, creating a clear spring cohort. Growth and age at maturity of males in the spring and autumn cohorts were estimated. Variance was too high for these parameters to be estimated in the winter cohort. Growth rates of males over 12 weeks of age did not differ from those reported in laboratory rearing studies. Estimated average age at maturity ranged from 20 to 32 weeks, depending on temperature.     

Recording electrical activity from the brain of behaving octopus

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Population genetics of the common long-armed octopus Octopus minor (Sasaki, 1920) (Cephalopoda: Octopoda) in Chinese waters based on microsatellite analysis

Octopus minor (Sasaki, 1920) is a commercially important cephalopod in Chinese waters. To provide a theoretical basis for resource protection and sustainable management, we investigated genetic structure of ten O. minor populations in Chinese waters using microsatellite DNA markers. Eight microsatellite loci revealed high allelic diversity with 11–26 alleles per locus. Observed and expected heterozygosity varied from 0.412 to 0.900 and from 0.337 to 0.845, respectively. The overall F_ST value was 0.198, indicating great genetic differentiation among populations. The F_ST value between Yilan and other populations reached more than 0.3 that may be indicative of subspecies rank. Mantel test showed significant correlations between genetic and geographic distance (R = 0.383, P = 0.004) indicating that genetic differentiation of O. minor conformed to a pattern of isolation-by-distance. Using the Neighbor-joining method, cluster analysis divided nine populations into three groups and divided ten populations into two groups wherein Yilan was distinguished from the other populations. Analysis based on F_ST, D_c values and clustering highlighted the heterogeneity of Yilan and the relative homogeneity between Yilan and Ganyu. The significant population genetic structure of O. minor is related to the combined effects of geographical barriers, current features and life history characteristics.     

Isolation and characterization of novel tachykinins from the posterior salivary gland of the common octopus Octopus vulgaris

Two novel tachykinins (OctTK-I: Lys-Pro-Pro-Ser-Ser-Ser-Glu-Phe-Ile-Gly-Leu-Met-NH(2) and OctTK-II: Lys-Pro-Pro-Ser-Ser-Ser-Glu-Phe-Val-Gly-Leu-Met-NH(2)) were isolated from the posterior salivary gland of the octopus (Octopus vulgaris) using a contraction assay of the carp rectum. These peptides had in common the pentapeptide sequence -Phe-X-Gly-Leu-Met-NH(2) at the C-terminal and induced immediate contractions on the carp rectum and the guinea-pig ileum. cDNAs encoding their precursor proteins were cloned. The OctTK gene was expressed in the posterior salivary gland and the expression was localized in mucus-secreting cells of the gland. The results suggested that OctTKs might be secreted as a venomous substance acting on vertebrates such as fishes, which are the prey or natural enemies of the octopus.     

Environmental assessment of common octopus (Octopus vulgaris) from a small-scale fishery in Algarve (Portugal)

The International Journal of Life Cycle Assessment - Common octopus is the fishing species with highest economic revenue in Portugal, and its consumption per capita is very high. The majority of...     

Seasonal changes of progesterone and testosterone concentrations throughout gonad maturation stages of the Mexican octopus,Octopus maya (Octopodidae: Octopus)

Variations in progesterone (P₄) and testosterone (T) levels in the gonad of Octopus maya from Sisal in Yucatan State, Mexico, were investigated by radioimmunoassays and in relation to four gonad maturation stages (GMS) and to the reproductive cycle, as represented by two maturity indices (microscopic ‘MiMI’ and macroscopic ‘MaMI’). According to the GMS and the maturity indices, the reproductive season of O. maya from Yucatan occurred from February to June. In females, P₄ and T displayed the same pattern, with a tendency to increase at the same time, although on average, P₄ had seven-fold higher concentrations than T. In contrast, P₄ and T in male gonads displayed a different pattern, where T concentrations were relatively stable throughout all of the study months. In the female gonad P₄ was lowest (close to 0 pg?g^–1) during both developing (GMS-I) and maturing (GMS-II) stages, and increased (189?±?53?pg?g^–1) approaching the mature stage (GMS-III) to a maximum value of 611?pg?g^–1. Concentrations of T in the male gonad were lowest (106?±?9?pg?g^–1) during the maturing stage (GMS-II) and increased up to the mature stage (GMS-III), reaching a maximum of 440?pg?g^–1. Pearson's correlation (r) between hormones and maturity indices showed strong relationships for females (around 0.4 and ?0.7; p?<?0.05), but there were negligible or weak relationships for males (0.2 and ?0.1; p?>?0.05). Hormone correlations in females were inverse with MaMI and direct with MiMI. Our major findings showed that gonadal P₄ levels were elevated during GMS-III and GMS-IV (i.e. periods of vitellogenic oocytes), where the characteristic aspect is an ovary with very high oocyte diameters, with the primary follicle cells deeply infolded in the ooplasm for yolk synthesis. These results suggested a synchrony between P₄ and the process of folliculogenesis, and in turn, vitellogenesis.     

Blood lipids of the small octopus,Octopus tehuelchus (mollusca,cephalopoda) at different stages of sexual maturation

• 1.1. The lipid and fatty acid composition from the plasma and hemocytes in Octopus tehuelchus at different stages of sexual development, was determined.
• 2.2. The highest content of lipids was found in females engaged in egg development, and the lowest in post-spawning and brooding females. Highest levels occurred during the autumn season in both sexes.
• 3.3. Changes were mainly due to triacylglycerols and diacylglyceryl ethers.
• 4.4. The plasma fatty acid composition did not demonstrate significant changes at different stages of maturation. The arachidonic acid (20:4 ω 6) was present at surprisingly high levels.

     

Antioxidant peptides isolated from the marine rotifer,Brachionus rotundiformis

Protein derived from the rotifer Brachionus rotundiformis was hydrolyzed using different proteases (Alcalase, α-chymotrypsin, Neutrase, papain, pepsin and trypsin) for production of antioxidant peptide. Antioxidant activities of hydrolysates were evaluated using DPPH radical scavenging activity. Peptic hydrolysate exhibited the highest antioxidative activity compared to other hydrolysates. To identify antioxidant peptides, peptic hydrolysate was purified using consecutive chromatographic methods, and antioxidant peptides were identified to be Leu-Leu-Gly-Pro-Gly-Leu-Thr-Asn-His-Ala (1076 Da), and Asp-Leu-Gly-Leu-Gly-Leu-Pro-Gly-Ala-His (1033 Da) by Q-TOF ESI mass spectroscopy. EC₅₀ values of purified peptides were 189.8 and 167.7 μM, respectively. Antioxidant activities of peptides purified from the rotifer protein hydrolysate were evaluated, with results showing that peptides significantly quenched free radicals.     

Functional characterization on invertebrate and vertebrate tissues of tachykinin peptides from octopus venoms

It has been previously shown that octopus venoms contain novel tachykinin peptides that despite being isolated from an invertebrate, contain the motifs characteristic of vertebrate tachykinin peptides rather than being more like conventional invertebrate tachykinin peptides. Therefore, in this study we examined the effect of three variants of octopus venom tachykinin peptides on invertebrate and vertebrate tissues. While there were differential potencies between the three peptides, their relative effects were uniquely consistent between invertebrate and vertebrae tissue assays. The most potent form (OCT-TK-III) was not only the most anionically charged but also was the most structurally stable. These results not only reveal that the interaction of tachykinin peptides is more complex than previous structure–function theories envisioned, but also reinforce the fundamental premise that animal venoms are rich resources of novel bioactive molecules, which are useful investigational ligands and some of which may be useful as lead compounds for drug design and development.     

Gonadal development and reproductive strategies of the tropical octopus (Octopus insularis) in northeast Brazil

Octopus insularis inhabits shallow waters along the coast and oceanic islands of northeastern Brazil, where it is the main target of commercial fishing of octopuses. This study aims to investigate the hypothesis that the tropical O. insularis has a distinct gonadal development and reproductive features when compare to its congener O. vulgaris from the subtropical regions. In order to describe its reproductive development, 545 octopuses were collected in the Northeastern Brazil. A good correspondence was observed between the gonad morphology and its histological structure. Oocytes in different development stages were observed in mature females. Most female in early maturity stages had sperm stored in the spermathecae, indicating that females copulate when still immature. There was no correlation between testis weight and the Needham complex, suggesting a protracted period of spermatophore production. Octopus insularis has a general gonadal development pattern similar to O. vulgaris, however, some differences were observed, as maturation at a smaller size, probably associated to a shorter life, and lower fecundity. The distinct reproductive features of O. insularis seem to be related to less variable conditions in the tropical environments. Management should take into account the differences and establish specific rules for the Northeast Brazil octopus fisheries.     

Isolation and characterization of a novel small cardioactive peptide-related peptide from the brain of Octopus vulgaris

A novel small cardioactive peptide (SCP)-related peptide (oct-SCPRP: Ser-Asn-Gly-Tyr-Leu-Ala-Leu-Pro-Arg-Gln-NH2) was isolated from the brain of the octopus (Octopus vulgaris). cDNA encoding this precursor protein was cloned. Oct-SCPRP was shown to evoke contraction in the radula protractor muscle, and the precursor protein was highly homologous to the SCP family in the Mollusk but did not encode a related peptide, SCPB. The expression of oct-SCPRP mRNA was present not only in the peripheral nervous system (PNS) which is a motor center for the control of feeding, but also in the central nervous system (CNS) which is capable of complex analysis, learning, and controls behaviors.     

Post-hatching development of the brain in Octopus ocellatus

To investigate the post-hatching development of the brain in a benthic octopod, Octopus ocellatus, we performed volumetric analyses of the brain. The brain consisting of the supra- and subesophageal masses was divided into 5 regions according to the functions suggested for the brain of another benthic octopod Octopus vulgaris, and the volume of each region was estimated at three post-hatching ages. We found that the inferior frontal lobe system and the brachial lobe increased in relative volume as the animals grew, while the basal lobe system decreased in relative volume. This result suggests that increasing demand for processing tactile information after hatching is reflected in the higher developmental rate in the centers devoted for tactile sense and related learning. We also found that the inner neuropile layer mainly consisting of dendrites, synapses and axons showed great increases in volume compared with the outer neural-cell-body layer. Although the increase in volume of the inner layer was marked during 1 month after hatching in all brain regions examined, the extent of the increase varied among brain regions. Developmental changes in cell densities in the outer layer also varied among the regions. The present results suggest that the post-hatching development of the brain in O. ocellatus is not homogeneous but varies among brain regions depending on different roles in controlling the behavior.