The purification and partial characterization of carp,Cyprinus carpio,vitellogenin

A procedure is described for the isolation of intact vitellogenin (c-VTG) from the carp, Cyprinus carpio. VTG was induced in juvenile females using oestradiol-17β and purified from the plasma using a combination of gel-filtration chromatography on Sepharose 6B and ion exchange chromatography on DEAE-cellulose. Purification procedures were conducted at low temperatures (below 9°C) in the presence of the proteolytic enzyme inhibitor aprotinin to prevent degradation. Intact c-VTG had an apparent molecular mass of 390,000 Daltons, but when extracted from plasma in the absence of aprotinin it underwent proteolysis into at least 2 protein fragments (apparent molecular masses of 230,000 and 96,000 Daltons), showing an instability of the native dimer. An amino acid analysis of c-VTG showed that its composition was almost identical to goldfish VTG, a species closely allied to the true carps and also similar to other oviparous vertebrate VTGs. Collectively, these data indicate that using these purification procedures VTG from carp, and probably other teleost species, can be isolated in an intact, highly purified form.     

A study of goldfish oocyte meiosisin vitro: effects of 2,4-dinitrophenol and adenosine-5-triphosphate

Germinal vesicle migration (GVM) and/or dissolution (GVD) were measured in goldfish oocytes, treated with 17α, 20β dihydroxyprogesterone (DHP) and other compounds considered to effect the cytoskeleton and oxidative phosphorylation,in vitro. Administration of DHP reinitiated meiotic maturation, increasing GVM and GVD in goldfish oocytes. Addition of 2,4-dinitrophenol (DNP) to the incubation medium significantly inhibited DHP-induced GVM and GVD. The DNP effect was found to be partially reversible after 24 h and could be reversed fully after a further delay of approximately 24h. Treatment of goldfish oocytes with demecolcine (DE; a colchicine derivative also known as colcemid) induces GVM to the micropyle without effecting GVD; while Cytochalasin-B which inhibits microfilament polymerization impairs both GVM and GVD. Administration of DNP, significantly inhibited DE-induced GVM, suggesting that GVM as well as GVD are dependent upon the process of oxidative phosphorylation. Addition of adenosine-5′ -triphosphate (ATP) at low concentrations (0.01–0.1 mM) did not effect DHP-induced or DNP-inhibited GVD in goldfish oocytes. The present results are consistent with the idea that migration of the oocyte nucleus during meiosis reinitiation has an energy requirement and involves participation by the cytoskeleton.     

Tolerance of juvenile black sea bass Centropristis striata to acute ammonia and nitrite exposure at various salinities

ABSTRACT:   Experiments were conducted to determine the acute tolerance of juvenile (mean weight ± standard error, 9.9 ± 0.9 g) black sea bass Centropristis striata to environmental un-ionized ammonia-nitrogen (NH₃-N) and nitrite-nitrogen (NO₂-N) exposure at various salinities. Specifically, median lethal concentrations (LC50 values) of NH₃-N and NO₂-N at 24, 48 and 96 h of exposure were determined at salinities of 10, 20 and 30 g/L at 22°C. With the exception of LC50 values determined at 48 h, median lethal concentrations of NH₃-N to black sea bass were not influenced by environmental salinity; 24, 48, and 96 h LC50 values ranged from 0.81 to 0.85, 0.65–0.77, and 0.46–0.54 mg-NH₃-N/L, respectively. In contrast, tolerance of black sea bass to environmental NO₂-N was compromised at reduced salinities. Median lethal concentrations of NO₂-N to fish at 24, 48 and 96 h of exposure ranged from 288.3 to 429.0, 258.4 to 358.8 and 190.0 to 241.9 mg-NO₂-N/L, respectively. Results indicate that while juvenile black sea bass are relatively sensitive to acute NH₃-N exposure, they are highly resistant to NO₂-N exposure.     

Endotoxin Structures in the Psychrophiles Psychromonas marina and Psychrobacter cryohalolentis Contain Distinctive Acyl Features

Lipid A is the essential component of endotoxin (Gram-negative lipopolysaccharide), a potent immunostimulatory compound. As the outer surface of the outer membrane, the details of lipid A structure are crucial not only to bacterial pathogenesis but also to membrane integrity. This work characterizes the structure of lipid A in two psychrophiles, Psychromonas marina and Psychrobacter cryohalolentis, and also two mesophiles to which they are related using MALDI-TOF MS and fatty acid methyl ester (FAME) GC-MS. P. marina lipid A is strikingly similar to that of Escherichia coli in organization and total acyl size, but incorporates an unusual doubly unsaturated tetradecadienoyl acyl residue. P. cryohalolentis also shows structural organization similar to a closely related mesophile, Acinetobacter baumannii, however it has generally shorter acyl constituents and shows many acyl variants differing by single methylene (-CH₂-) units, a characteristic it shares with the one previously reported psychrotolerant lipid A structure. This work is the first detailed structural characterization of lipid A from an obligate psychrophile and the second from a psychrotolerant species. It reveals distinctive structural features of psychrophilic lipid A in comparison to that of related mesophiles which suggest constitutive adaptations to maintain outer membrane fluidity in cold environments.     

Eight urgent,fundamental and simultaneous steps needed to restore ocean health,and the consequences for humanity and the planet of inaction or delay

1. The ocean crisis is urgent and central to human wellbeing and life on Earth; past and current activities are damaging the planet's main life support system for future generations. We are witnessing an increase in ocean heat, disturbance, acidification, bio‐invasions and nutrients, and reducing oxygen levels. Several of these act like ratchets: once detrimental or negative changes have occurred, they may lock in place and may not be reversible, especially at gross ecological and ocean process scales.
2. Each change may represent a loss to humanity of resources, ecosystem function, oxygen production and species. The longer we pursue unsuitable actions, the more we close the path to recovery and better ocean health and greater benefits for humanity in the future.
3. We stand at a critical juncture and have identified eight priority issues that need to be addressed in unison to help avert a potential ecological disaster in the global ocean. They form a purposely ambitious agenda for global governance and are aimed at informing decision‐makers at a high level. They should also be of interest to the general public.
4. Of all the themes, the highest priority is to rigorously address global warming and limit surface temperature rise to 1.5°C by 2100, as warming is the pre‐eminent factor driving change in the ocean. The other themes are establishing a robust and comprehensive High Seas Treaty, enforcing existing standards for Marine Protected Areas and expanding their coverage, especially in terms of high levels of protection, adopting a precautionary pause on deep‐sea mining, ending overfishing and destructive fishing practices, radically reducing marine pollution, putting in place a financing mechanism for ocean management and protection, and lastly, scaling up science/data gathering and facilitating data sharing.
5. By implementing all eight measures in unison, as a coordinated strategy, we can build resilience to climate change, help sustain fisheries productivity, particularly for low‐income countries dependent on fisheries, protect coasts (e.g. via soft‐engineering/habitat‐based approaches), promote mitigation (e.g. carbon storage) and enable improved adaptation to rapid global change.

     

Novel insights into the marine phase and river fidelity of anadromous twaite shad Alosa fallax in the UK and Ireland

1. Most research on anadromous fishes has been invested in their freshwater life‐phases, resulting in a relatively sparse understanding of their spatial ecology during marine life‐phases. However, understanding the marine dispersal of anadromous fishes is essential to identify threats and to implement conservation measures that fully encompass their lifecycle.
2. The twaite shad Alosa fallax is an anadromous fish increasingly imperilled across its range due to pollution, harvesting, and impediments to freshwater migration, but little is known about its distribution and movements during its marine life‐phase. Here, the application of acoustic telemetry provided novel insights into the coastal dispersal of twaite shad in the UK and Ireland during 2018–2019, and the freshwater entry of individuals during the 2019 spawning season.
3. Of 73 twaite shad acoustic‐tagged during their upstream migration in the River Severn in May 2018, 58 emigrated from the river. Twelve were subsequently detected 200 km to the south‐west at the Taw–Torridge Estuary between July 2018 and April 2019, where estuarine movements up to 5.8 km inland occurred in summer, winter, and spring. One was subsequently detected in the Munster Blackwater Estuary (Ireland) and then in the River Severn, indicating a minimum movement distance of 950 km. Thirty‐four (59%) of the emigrating individuals from 2018 re‐entered fresh water in the rivers Severn (n = 33) and Wye (n = 2) in April and May 2019.
4. These results suggest year‐round use of estuarine and nearshore habitats by at least a subset of the twaite shad population during their marine phase, providing evidence of potential range overlap between populations that spawn in different areas in the UK and Ireland, which may be facilitated by substantial dispersal. The results also highlight the potential of telemetry for estimating freshwater and marine mortality, and the benefits of sharing detection data across networks.

     

SOME SELECTIVE EFFECTS OPERATING ON WHITE- AND RED-CLOVER IN SWARDS

Populations of white- and red-clover were examined after they had been grown for several years in grass/clover swards. The method of sowing, nitrogen application, management and season affected the ratio of very similar clover cultivars differing specifically in the leaf mark when sown in the same mixture. The companion grass also infiuenced the proportion of legume cultivars in the sward. In addition, the mean date of emergence of a single cultivar of broad-red clover was affected by management.     

The potential of replacing conventional dairy supplements with forage legume-based diets in Zimbabwe’s smallholder dairy sector

The effect of replacing commercial supplements with isoenergetic and isonitrogenous velvet bean-, cowpeaand lablab-based supplements on milk yield, milk quality and economic returns in smallholder crossbred dairy cows was investigated in the 2013 and 2014 dry seasons. Using 3 × 3 Latin square designs, nine multiparous Red Dane, Guernsey and Holstein-Friesian crosses in mid-lactation (130 ± 19 d) were offered forage legume-based supplements for 63 d at 0.5 kg per litre of milk produced. Milk quantity and quality were significantly (P < 0.05) different among supplements in both seasons. Cows fed commercial supplements had higher milk yield than cows fed forage legume supplements. Milk fat content was significantly (p < 0.05) higher in cows fed lablab-based supplements than cows fed other supplements. Milk protein, total solids and lactose content of cows fed commercial supplements was significantly (p < 0.05) higher than those fed forage legume-based supplements, although protein content was similar to cows fed lablab-based supplements. Dietary gross margins were higher for cows fed velvet beanand lablab-based supplements by 17% and 16.5%, respectively. Based on supplement, production costs per litre of milk was higher by 28% and 23% using commercial supplements compared to velvet bean and lablab supplements, respectively.