Options in dealing with marine alien species

Invasive species can have strong impact on the local ecosystem, not only substantial impact on the local ecosystem, but also on economy and human health. This review on marine alien species outlines aspects of prevention, eradication and control strategies. When managing invasive species, prevention is preferable and less costly than controlling species. Especially for marine environments, invasive species can disperse rapidly and can be particularly hard to detect

Natuurwaarden Borkumse Stenen: project aanvullende beschermde gebieden

In dit rapport wordt de bodemfauna in het gebied ‘Borkumse Stenen’ beschreven. Het gebied ‘Borkumse Stenen’ ligt ten noorden van Schiermonnikoog en grenst aan de zuidzijde aan het Nederlandse Natura 2000-gebied Noordzeekustzone en aan de oostzijde aan het Duitse Natura 2000-gebied ‘Borkum Riffgrund’, dat o.a. vanwege de aanwezigheid van habitattype H1170 (‘riffen’) is aangewezen

High corticosterone and sex reversal in common carp (Cyprinus carpio L.) with adrenal hyperplasia caused by P450c17a2 deficiency

The aim of this study was to investigate the inheritance of adrenal hyperplasia, caused by 17a-hydroxylase deficiency, and its association with female to male sex reversal in common carp. Inbred strains used in this experiment were E4 (XX, female, normal), E5 (XX, male, adrenal hyperplasia) and E7 (XX, male, adrenal hyperplasia). F1 females (E4E5: XX, normal) were crossed to E5 and E7 males to produce backcross progeny (BC5 and BC7), or reproduced by gynogenesis to produce doubled haploid progeny (DH). Fish (age 6 months) were subjected to a net confinement stressor and sacrificed to collect blood plasma for analysis of cortisol and corticosterone, and to determine sex. Values for plasma corticosterone showed a clear segregation pattern, consistent with a single recessive gene model. There was a highly significant difference between high and low corticosterone responders in BC and DH progeny groups. Mean corticosterone values for high corticosterone responders in the three groups BC5, BC7 and DH were, respectively: 1706, 1760 and 1366 ng/ml. For low corticosterone responders values were 1.5, 1.1 and 0.6 ng/ml. High corticosterone responders had on average low levels of cortisol: 21.3, 24 and 17.3 ng/ml for BC5, BC7 and DH. Low corticosterone responders had normal levels (66.7, 105.1 and 65.2 ng/ml for BC5, BC7 and DH, respectively). Sex ratios were significantly different between high and low corticosterone responders. High corticosterone responders were predominantly male, while low corticosterone responders were female or intersex. High corticosterone responders had well developed testis and were fertile indicating that in the gonads, 17a-hydroxylase is not impaired. The observed effect on sex shows that 17a-hydroxylase deficiency most likely augments sex reversal in common carp, either directly through high levels of plasma corticosterone, or through paracrine effects of elevated ACTH production

High corticosterone and sex reversal in common carp (Cyprinus carpio L.) with adrenal hyperplasia caused by P450c17a2 deficiency

The aim of this study was to investigate the inheritance of adrenal hyperplasia, caused by 17a-hydroxylase deficiency, and its association with female to male sex reversal in common carp. Inbred strains used in this experiment were E4 (XX, female, normal), E5 (XX, male, adrenal hyperplasia) and E7 (XX, male, adrenal hyperplasia). F1 females (E4E5: XX, normal) were crossed to E5 and E7 males to produce backcross progeny (BC5 and BC7), or reproduced by gynogenesis to produce doubled haploid progeny (DH). Fish (age 6 months) were subjected to a net confinement stressor and sacrificed to collect blood plasma for analysis of cortisol and corticosterone, and to determine sex. Values for plasma corticosterone showed a clear segregation pattern, consistent with a single recessive gene model. There was a highly significant difference between high and low corticosterone responders in BC and DH progeny groups. Mean corticosterone values for high corticosterone responders in the three groups BC5, BC7 and DH were, respectively: 1706, 1760 and 1366 ng/ml. For low corticosterone responders values were 1.5, 1.1 and 0.6 ng/ml. High corticosterone responders had on average low levels of cortisol: 21.3, 24 and 17.3 ng/ml for BC5, BC7 and DH. Low corticosterone responders had normal levels (66.7, 105.1 and 65.2 ng/ml for BC5, BC7 and DH, respectively). Sex ratios were significantly different between high and low corticosterone responders. High corticosterone responders were predominantly male, while low corticosterone responders were female or intersex. High corticosterone responders had well developed testis and were fertile indicating that in the gonads, 17a-hydroxylase is not impaired. The observed effect on sex shows that 17a-hydroxylase deficiency most likely augments sex reversal in common carp, either directly through high levels of plasma corticosterone, or through paracrine effects of elevated ACTH production

Transcript levels of five enzymes involved in cortisol synthesis and regulation during the stress response in common carp: Relationship with cortisol

In this study the expression of five genes involved in cortisol synthesis and regulation in the head kidneys of common carp (Cyprinus carpio L.) has been investigated in response to 3 h net confinement stress, followed by 22 h recovery. Cortisol, glucose, lactate and free fatty acid levels were measured in blood plasma. StAR, P450c17a2, 3ßHSD, P450c21 and 11ßHSD2 transcript sequences were identified based on Cyprinidae homologs and quantified by real-time PCR. Results showed that the plasma cortisol level reached a peak at one hour post-stress (85-fold higher than in control) and quickly returned to normal after 4 h recovery. 11ßHSD2 transcripts were for the first time identified in interrenals. Changes in cortisol levels during and after confinement were correlated in a time-delayed relationship with increase and decrease in mRNA levels of 11ßHSD2, respectively. These results suggest that cortisol may be involved in the control or activation of 11ßHSD2. StAR and P450c21 mRNA levels did not change during net confinement stress and recovery, but P450c17a2 levels were significantly increased 4 and 22 h after recovery. Since plasma cortisol levels increased by 68-fold within 5 min net confinement stress, it seems that transcriptional activation of this enzyme is not directly involved in acute cortisol production

Options in dealing with marine alien species

Invasive species can have strong impact on the local ecosystem, not only substantial impact on the local ecosystem, but also on economy and human health. This review on marine alien species outlines aspects of prevention, eradication and control strategies. When managing invasive species, prevention is preferable and less costly than controlling species. Especially for marine environments, invasive species can disperse rapidly and can be particularly hard to detect

Transcript levels of five enzymes involved in cortisol synthesis and regulation during the stress response in common carp: Relationship with cortisol

In this study the expression of five genes involved in cortisol synthesis and regulation in the head kidneys of common carp (Cyprinus carpio L.) has been investigated in response to 3 h net confinement stress, followed by 22 h recovery. Cortisol, glucose, lactate and free fatty acid levels were measured in blood plasma. StAR, P450c17a2, 3ßHSD, P450c21 and 11ßHSD2 transcript sequences were identified based on Cyprinidae homologs and quantified by real-time PCR. Results showed that the plasma cortisol level reached a peak at one hour post-stress (85-fold higher than in control) and quickly returned to normal after 4 h recovery. 11ßHSD2 transcripts were for the first time identified in interrenals. Changes in cortisol levels during and after confinement were correlated in a time-delayed relationship with increase and decrease in mRNA levels of 11ßHSD2, respectively. These results suggest that cortisol may be involved in the control or activation of 11ßHSD2. StAR and P450c21 mRNA levels did not change during net confinement stress and recovery, but P450c17a2 levels were significantly increased 4 and 22 h after recovery. Since plasma cortisol levels increased by 68-fold within 5 min net confinement stress, it seems that transcriptional activation of this enzyme is not directly involved in acute cortisol production

High levels of corticosterone and gene expression of star, cyp17a2, hsd3b, cyp21, hsd11b2 during acute stress in common carp with interrenal hyperplasia

We investigated the acute stress response in a common carp strain (E5) with interrenal hyperplasia due to 17a-hydroxylase deficiency, and in an isogenic standard (STD) carp strain. Cortisol, corticosterone and the head kidney-somatic index were measured during and after a 3 h net confinement stress. Star, cyp17a2, hsd3b, cyp21, hsd11b2 mRNA levels were measured in head kidneys using real-time qPCR. The results show very high corticosterone levels and enlargement of the head kidney in E5 fish. This is the first report in a teleost fish showing a significant increase of corticosterone levels in response to stress due to interrenal hyperplasia. The high levels of corticosterone in E5 suggest that corticosterone is not converted to aldosterone in common carp. star and hsd3b mRNA levels were significantly higher in E5 compared to STD fish, while cyp17a2 levels were significantly lower in E5. In contrast to E5, star levels did not change during stress and recovery in STD, suggesting that the enzyme is regulated in a different manner in E5 and STD fish. In E5, the levels of cyp17a2 dropped below control values after 20 min stress. These findings strongly suggest that cyp17a2 is impaired at (post)-transcriptional level. As a consequence the accumulated precursor (pregnenolone) is not converted to cortisol, but to corticosterone. In contrast to STD, significant levels of cortisol could not be detected in E5. Finally, hsd11b2 mRNA levels were significantly lower in E5 compared to STD, and did not change during stress and recovery. These results support the idea that hsd11b2 is involved in the conversion of physiologically active cortisol to inactive cortisone, as reported earlier for STD carp. In conclusion our results show high levels of corticosterone in E5 and differences in star and mRNA levels of steroidogenic genes between E5 and STD carp during net confinement stress

Extraction of collagen from fish skins and its use in manufacture of biopolymer films

The aim of this study was to extract collagen from fish skins and investigate the physical properties of the biodegradable films formed from the extracted fish collagen. Extraction of collagen using hydrogen peroxide or enzymatic methods proved to be unsuccessful. A white collagen substance was successfully extracted using a hydrochloric acid extraction method; however, it was unsuitable for the formation of edible films. An acetic acid extraction process successfully yielded a collagen substance, which could be used to form biodegradable collagen films. Differences in the mechanical film properties, tensile strength, Young's modulus, elongation and water vapor permeability were found between collagen films from different fish species. Films formed from collagen of New Zealand (NZ) hoki and NZ ling had greater elongation (%EL), tensile strength (TS) and elasticity in comparison with similar films from Irish (IRL) fish species. The addition of plasticizer to the collagen films had an effect on the mechanical properties of the film