Antarctic marine life under pressure

Next week, the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR) convenes in Hobart, Tasmania, to examine the state of marine life in the Southern Ocean. As part of the Antarctic Treaty System, this convention entered into force in 1982, and its focus on the region’s environmental integrity has never been more important, given the increasing effects of climate change and commercial fishing. An important focus over the past 40 years has been Antarctic krill, Euphausia superba (hereafter krill), a keystone species that helps to hold this marine ecosystem together. Climate and fishing stresses should prompt the CCAMLR to address whether management of krill fishing is at a level that protects the Southern Ocean from losing its overall balance of marine life and the oceanic processes that regulate global climate. </jats:p

Mitochondrial import receptors for precursor proteins

The specific targeting of precursor proteins synthesized in the cytosol to various cell organelles is a central aspect of intracellular protein traffic. Several hundred different proteins are imported from the cytosol into the mitochondria. Recent studies have identified the mitochondrial outer membrane proteins MOM19, MOM72, MOM38 (≈ISP42) and p32 which have a role in initial steps of protein import. The first three components are present in a multi-subunit complex that catalyses recognition and membrane insertion of precursor proteins

Phytol-based novel adjuvants in vaccine formulation: 1. assessment of safety and efficacy during stimulation of humoral and cell-mediated immune responses

BACKGROUND: Vaccine efficacy depends significantly on the use of appropriate adjuvant(s) in the formulation. Phytol, a dietary diterpene alcohol, is similar in structure to naturally occurring isoprenoid adjuvants; but little is known of its adjuvanticity. In this report, we describe the relative safety and efficacy of phytol and its hydrogenated derivative PHIS-01 compared to commercial adjuvants. METHODS: We tested adjuvant properties using a formulation consisting of either a hapten, phthalate-conjugated to a protein, keyhole limpet hemocyanin (KLH), or ovalbumin (OVA) emulsified with the test adjuvants in mice without any surfactant. Humoral immunity was assessed in terms of titer, specificity, and isotypic profiles. The effect on cell-mediated immunity was studied by assaying the induction of either OVA- or B-lymphoma-specific cytotoxic T-lymphocyte (CTL) activity. RESULTS AND DISCUSSION: The phytol compounds, particularly PHIS-01, elicit increased titers of all major IgG subclasses, especially IgG2a. Unlike commercial adjuvants, both phytol compounds are capable of inducing specific cytotoxic effector T cell responses specific to both OVA and B-lymphoma tested. Phytols as adjuvants are also distinctive in that they provoke no adverse anti-DNA autoimmune response. Intraperitoneally administered phytol is comparable to complete Freund's adjuvant in toxicity in doses over 40 ug/mouse, but PHIS-01 has no such toxicity. CONCLUSION: These results and our ongoing studies on antibacterial immunity show that phytol and PHIS-01 are novel and effective adjuvants with little toxicity

Correction: Phytol-based novel adjuvants in vaccine formulation: 1. assessment of safety and efficacy during stimulation of humoral and cell-mediated immune responses

This is a correction article

Photoperiodic modulation of circadian functions in Antarctic krill Euphausia superba Dana, 1850 (Euphausiacea)

An endogenous circadian clock influences metabolic output rhythms in the Antarctic krill (Euphausia superba Dana, 1850), a key species in the Southern Ocean ecosystem. Seasonal changes in photoperiod in Antarctica, ranging from midnight sun (24 h light) during mid-summer to very short days (3\u20134 h light) during mid-winter, represent a challenge for the synchronization of the krill circadian clock. We analyzed clock gene activity and clock output functions in krill exposed to different light conditions during a long-term photoperiodic simulation in the laboratory. In simulated early-autumn (light/dark or LD 16:8) and late-winter (LD 8:16) conditions, the circadian clock of krill was functional and the metabolic output was synchronized to the light/dark cycle, the clock genes Esper and Esclk peaked in antiphase around simulated dusk/dawn and most metabolic-related genes showed upregulation around simulated dusk. In contrast, in simulated mid-summer (light/light or LL) and mid-winter (LD 3:21) conditions, the synchronization of the circadian clock and the metabolic output appeared to be weaker, with clock gene expression becoming arrhythmic and upregulation of metabolic genes occurring at different times during the day. Early-autumn and late-winter photoperiodic cues in the laboratory thus seem to be sufficient to entrain the krill clock and promote metabolic synchronization, whereas midwinter and mid-summer photoperiodic cues seem to be insufficient for krill entrainment. Krill in the field may overcome the seasonal lack of overt photoperiodic cycle occurring during midsummer and mid-winter by using alternative light-related Zeitgebers (i.e., varying light intensity rather than the presence or absence of light) to promote basic homeostatic rhythms over 24 h

The Seasonal Metabolic Activity Cycle of Antarctic Krill (Euphausia superba): Evidence for a Role of Photoperiod in the Regulation of Endogenous Rhythmicity

Antarctic krill (Euphausia superba), a key species in the Southern Ocean, reduce their metabolism as an energy saving mechanism in response to the harsh environmental conditions during the Antarctic winter. Although the adaptive significance of this seasonal metabolic shift seems obvious, the driving factors are still unclear. In particular, it is debated whether the seasonal metabolic cycle is driven by changes in food availability, or if an endogenous timing system entrained by photoperiod might be involved. In this study, we used different long-term photoperiodic simulations to examine the influence of light regime and endogenous rhythmicity on the regulation of krill seasonal metabolic cycle. Krill showed a seasonal cycle of growth characterized by null-to-negative growth rates during autumn-winter and positive growth rates during spring-summer, which was manifested also in constant darkness, indicating strong endogenous regulation. Similar endogenous cycles were observed for the activity of the key-metabolic enzyme malate dehydrogenase (MDH) and for the expression levels of a selection of metabolic-related genes, with higher values in spring-summer and lower values in autumn-winter. On the other side, a seasonal cycle of oxygen consumption was observed only when krill were exposed to simulated seasonal changes in photoperiod, indicating that light-related cues might play a major role in the regulation of krill oxygen consumption. The influence of light-regime on oxygen consumption was minimal during winter, when light-phase duration was below 8 h, and it was maximal during summer, when light-phase duration was above 16 h. Significant upregulation of the krill clock genes clk, cry2, and tim1, as well as of the circadian-related opsins rh1a and rrh, was observed after light-phase duration had started to decrease in early autumn, suggesting the presence of a signaling cascade linking specific seasonal changes in the Antarctic light regime with clock gene activity and the regulation of krill metabolic dormancy over the winter

Functional outcome of adulthood selective dorsal rhizotomy for spastic diplegia

Objective The medical evidence supporting the efficacy of selective dorsal rhizotomy (SDR) on children with spastic diplegia is strong. However, the outcome of SDR on adults with spastic diplegia remains undetermined. The aim is to study the effectiveness and morbidities of SDR performed on adults for the treatment of spastic diplegia. Methods Patients who received SDR in adulthood for the treatment of spastic diplegia were surveyed. The survey questionnaire addressed the living situation, education level, employment, health outcomes, postoperative changes of symptoms, changes in ambulatory function, adverse effects of SDR and orthopedic surgery after SDR. Results The study included 64 adults, who received SDR for spastic diplegia. The age at the time of surgery was between 18 and 50 years. The age at the time of the survey was between 20 and 52 years. The follow-up period ranged from one to 28 years. The study participants reported post-SDR improvements of the quality of walking in 91%, standing in 81%, sitting in 57%, balance while walking 75%, ability to exercise in 88%, endurance in 77%, and recreational sports in 43%. Muscle and joint pain present before surgery improved in 64% after surgery. Concerning the level of ambulatory function, all patients who walked independently in all environments maintained the same level of ambulatory function. Eighteen percent of the patients who walked independently in some environments improved to the independent walking in all environments. All patients who walked with an assistive device before SDR maintained the assistive walking after SDR. Concerning adverse effects of SDR, 50% (32 of 64 patients) developed numbness in the various parts of the legs. Two patients reported a complete loss of sensation in parts of the legs, and one patient reported numbness and constant pain in the bilateral lower extremities. Ten patients (16%) reported recurrent spasticity after SDR, and three patients (5%) reported ankle clonus, which is an objective sign of spasticity. Tendon lengthening surgery after SDR was needed in 27% and hip and knee surgery in 2% and 6%, respectively. Conclusions The great majority of our 64 patients, who received adulthood SDR for spastic diplegia, improved the quality of ambulation and abated signs of early aging. Numbness and diminished sensation in the lower extremity was the most common adverse effect of the adulthood SDR

Analysis of the circadian transcriptome of the Antarctic krill Euphausia superba

Antarctic krill (Euphausia superba) is a high latitude pelagic organism which plays a central role in the Southern Ocean ecosystem. E. superba shows daily and seasonal rhythms in physiology and behaviour, which are synchronized with the environmental cycles of its habitat. Recently, the main components of the krill circadian machinery have been identified and characterized. However, the exact mechanisms through which the endogenous timing system operates the control and regulation of the overt rhythms remains only partially understood. Here we investigate the involvement of the circadian clock in the temporal orchestration of gene expression by using a newly developed version of a krill microarray platform. The analysis of transcriptome data from krill exposed to both light-dark cycles (LD 18:6) and constant darkness (DD), has led to the identification of 1,564 putative clock-controlled genes. A remarkably large proportion of such genes, including several clock components (clock, period, cry2, vrille, and slimb), show oscillatory expression patterns in DD, with a periodicity shorter than 24\u2009hours. Energy-storage pathways appear to be regulated by the endogenous clock in accordance with their ecological relevance in daily energy managing and overwintering. Our results provide the first representation of the krill circadian transcriptome under laboratory, free-running conditions

Light regime affects the seasonal cycle of Antarctic krill (Euphausia superba): impacts on growth, feeding, lipid metabolism, and maturity

Light regime is an important zeitgeber for Antarctic krill (Euphausia superba Dana, 1850), which seems to entrain an endogenous timing system that synchronizes its life cycle to the extreme light conditions in the Southern Ocean. To understand the flexibility of Antarctic krill’s seasonal cycle, we investigated its physiological and behavioural responses to different light regimes and if an endogenous timing system was involved in the regulation of these seasonal processes. We analysed growth, feeding, lipid content, and maturity in a 2-year laboratory experiment simulating the latitudinal light regimes at 52°S and 66°S and constant darkness under constant food level. Our results showed that light regime affected seasonal cycles of growth, feeding, lipid metabolism, and maturity in Antarctic krill. Seasonal patterns of growth, feeding, and maturity persisted under constant darkness, indicating the presence of an endogenous timing system. The maturity cycle showed differences in critical photoperiods according to the simulated latitudinal light regime. This suggests a flexible endogenous timing mechanism in Antarctic krill, which may determine its response to future environmental changes

The Seasonal Metabolic Activity Cycle of Antarctic Krill (Euphausia superba): Evidence for a Role of Photoperiod in the Regulation of Endogenous Rhythmicity

Antarctic krill (Euphausia superba), a key species in the Southern Ocean, reduce their metabolism as an energy saving mechanism in response to the harsh environmental conditions during the Antarctic winter. Although the adaptive significance of this seasonal metabolic shift seems obvious, the driving factors are still unclear. In particular, it is debated whether the seasonal metabolic cycle is driven by changes in food availability, or if an endogenous timing system entrained by photoperiod might be involved. In this study, we used different long-term photoperiodic simulations to examine the influence of light regime and endogenous rhythmicity on the regulation of krill seasonal metabolic cycle. Krill showed a seasonal cycle of growth characterized by null-to-negative growth rates during autumn-winter and positive growth rates during spring-summer, which was manifested also in constant darkness, indicating strong endogenous regulation. Similar endogenous cycles were observed for the activity of the key-metabolic enzyme malate dehydrogenase (MDH) and for the expression levels of a selection of metabolic-related genes, with higher values in spring-summer and lower values in autumn-winter. On the other side, a seasonal cycle of oxygen consumption was observed only when krill were exposed to simulated seasonal changes in photoperiod, indicating that light-related cues might play a major role in the regulation of krill oxygen consumption. The influence of light-regime on oxygen consumption was minimal during winter, when light-phase duration was below 8 h, and it was maximal during summer, when light-phase duration was above 16 h. Significant upregulation of the krill clock genes clk, cry2, and tim1, as well as of the circadian-related opsins rh1a and rrh, was observed after light-phase duration had started to decrease in early autumn, suggesting the presence of a signaling cascade linking specific seasonal changes in the Antarctic light regime with clock gene activity and the regulation of krill metabolic dormancy over the winter