Working with living krill – the people and the places

The fascination of Antarctic scientists with Antarctic krill and their capabilities has a long and varied history, and prompted many scientists to maintain and manipulate krill under laboratory conditions. Starting in the Discovery era with Mackintosh at the King Edward Point labs on South Georgia, 1930, scientists have collected krill from sailing vessels, small boats, inflatable zodiacs and large ice-breaking vessels. Krill have been maintained in small and large jars, deep rectangular tanks, large round tanks and in flow-through and recycling systems. They have been maintained both on board research vessels and in laboratories, in flowing seawater systems at ambient conditions and in temperature-controlled environmental rooms. A few researchers have transported living krill back to their home laboratories, for example tropical laboratories in Japan (Murano) and Australia (Ikeda), temperate laboratories (Nicol) in Australia, a northern European laboratory in Germany (Marschall) and a sunny maritime laboratory in California (Ross and Quetin). The goals have been varied: short-term experiments to understand in situ physiological rates, long-term experiments to test the effects of manipulations or controlled changes in environmental conditions, and behavioral responses. We take you on a brief historical tour as we trace the lineage of modern day research on living Antarctic krill.     

The effectiveness of a bubble curtain for preventing physical damage to antarctic krill in captivity

Krill in captivity endure spatial restrictions, regardless of the size or shape of tank used. Visual inspection of freshly caught and captive animals suggests that their appendages, particularly the antennae and antennules, are often subject to injury. We have developed a novel method for reducing physical damage to captive krill based on their reported reaction to feeding whales. This method involves creating a bubble curtain that keeps the krill in the centre of the tank and away from potentially damaging hard surfaces. There was no difference in the length of the antennae between any of the captive animals. Trends in the data suggest that the antennules of krill maintained in a 200?L bubble curtain tank and a1000?L holding tank, were longer and less variable in length, than for krill in a 200?L tank with no bubble curtain. Freshly caught krill from the field were found to have damage to both antennae and antennules. The implications of these findings for husbandry of krill and for behavioural studies in the laboratory are discussed.     

The effectiveness of a bubble curtain for preventing physical damage to antarctic krill in captivity

Krill in captivity endure spatial restrictions, regardless of the size or shape of tank used. Visual inspection of freshly caught and captive animals suggests that their appendages, particularly the antennae and antennules, are often subject to injury. We have developed a novel method for reducing physical damage to captive krill based on their reported reaction to feeding whales. This method involves creating a bubble curtain that keeps the krill in the centre of the tank and away from potentially damaging hard surfaces. There was no difference in the length of the antennae between any of the captive animals. Trends in the data suggest that the antennules of krill maintained in a 200 L bubble curtain tank and a1000 L holding tank, were longer and less variable in length, than for krill in a 200 L tank with no bubble curtain. Freshly caught krill from the field were found to have damage to both antennae and antennules. The implications of these findings for husbandry of krill and for behavioural studies in the laboratory are discussed.     

Experiments on the physiology of southern and northern krill, Euphausia superba and Meganyctiphanes norvegica, with emphasis on moult and growth - a review

Physiological data are needed for life history studies on krill, and as parameters for input into energy budgets and models. In conjunction with moult and growth data, these may also prove useful for assessing the fishable biomass of krill. Here, the development of physiological concepts in experimental krill research is briefly evaluated, with emphasis on the gaps to be filled. Krill growth is very flexible, as well as strongly temperature and nutrition dependent. The polar Antarctic krill Euphausia superba grows as fast as the boreal species Meganyctiphanes norvegica, at least during the first 2.5 years, and the species are comparable in terms of physiological plasticity. Accordingly, as krill appear to adjust quickly to specific laboratory conditions, short-term experiments are essential if field conditions are to be reflected as closely as possible. Furthermore, direct comparisons between laboratory experiments and swarming studies in the field are advantageous. For these, M. norvegica is particularly well-suited, as swarms can be followed over longer times and more easily than in E. superba. For example, processes of moult and reproduction were found to be highly coordinated in swarms and populations of Northern krill. For this species a conceptual model of reproduction was developed based on a combination of short-term laboratory observations coupled with field data on moult and ovary stages. In further physiological experiments krill should be studied as groups when swarming. Using proxies, that is applying physiological and/or biochemical methods side by side, is a promising way to enhance the reliability of life history data.     

Living krill, zooplankton and experimental investigations: a discourse on the role of krill and their experimental study in marine ecology

Krill occupy critical positions in a many marine ecosystems and have been the subject of a number of concerted studies yet there are large areas of their biology that still remain a mystery. Most species of krill are open ocean animals, which makes direct observation and sampling difficult. Krill also exhibit a number of physiological and behavioural attributes which frustrate attempts to understand their life history. Krill are conceptually difficult to come to terms with; they are obviously different from larger marine organisms such as squid, fish, whales and fish yet they are also quite distinct from those animals classed as zooplankton such as copepods. Despite these differences they have most often been grouped with zooplankton and have been studied using techniques developed for animals which are orders of magnitude smaller than they. This mismatch has affected our view of their interactions with the physical world and also affects their perceived trophic interactions. Their size and mobility also interferes with our ability to sample them effectively and thus to develop our appreciation of their true role in the marine ecosystem. Understanding how intermediate-sized animals, such as krill, function in aquatic ecosystem is critical to better management of the marine environment.     

Effect of solar ultraviolet radiation on survival of krill larvae and copepods in Antarctic Ocean

The effect of solar ultraviolet radiation on the survival rate of Antarctic zooplankton was examined in February–March in 2002. We investigated survival rate of calyptopis larvae of Euphausia superba and late copepodite stages (IV and V) of large dominant calanoid species, Calanoides acutus and Calanus propinquus reared in quartz jars with three different radiation regimes (total radiation, exclusion of UVB, exclusion of UVA and UVB) and a dark control. The survival rates of the krill larvae decreased after 3 days from start of the experiment, being below 50% at 4 days in the treatments with total radiation and exclusion of UVB, although most individuals could survive until the end of the experiments in the treatments with exclusion of both UVA and UVB and dark control. The calanoid juveniles showed almost same pattern of survival curves as the krill larvae did, but survived slightly longer. Although >10% of surface UVA radiation at 340 and 380 nm penetrated down to 30 m, both C. acutus and C. propinquus were mostly distributed above 20 m. Surface swarm of the krill larvae can be often recognized in the previous studies. These results suggest that not only solar UVB but also UVA radiation potentially lower the survival rate of Antarctic zooplankton at depth less than 20 m.     

Living krill,zooplankton and experimental investigations: a discourse on the role of krill and their experimental study in marine ecology

Krill occupy critical positions in a many marine ecosystems and have been the subject of a number of concerted studies yet there are large areas of their biology that still remain a mystery. Most species of krill are open ocean animals, which makes direct observation and sampling difficult. Krill also exhibit a number of physiological and behavioural attributes which frustrate attempts to understand their life history. Krill are conceptually difficult to come to terms with; they are obviously different from larger marine organisms such as squid, fish, whales and fish yet they are also quite distinct from those animals classed as zooplankton such as copepods. Despite these differences they have most often been grouped with zooplankton and have been studied using techniques developed for animals which are orders of magnitude smaller than they. This mismatch has affected our view of their interactions with the physical world and also affects their perceived trophic interactions. Their size and mobility also interferes with our ability to sample them effectively and thus to develop our appreciation of their true role in the marine ecosystem. Understanding how intermediate-sized animals, such as krill, function in aquatic ecosystem is critical to better management of the marine environment.     

Rising population cost for treating people living with HIV in the UK, 1997-2013

Background

The number of people living with HIV (PLHIV) is increasing in the UK. This study estimated the annual population cost of providing HIV services in the UK, 1997–2006 and projected them 2007–2013.

Methods

Annual cost of HIV treatment for PLHIV by stage of HIV infection and type of ART was calculated (UK pounds, 2006 prices). Population costs were derived by multiplying the number of PLHIV by their annual cost for 1997–2006 and projected 2007–2013.

Results

Average annual treatment costs across all stages of HIV infection ranged from £17,034 in 1997 to £18,087 in 2006 for PLHIV on mono-therapy and from £27,649 in 1997 to £32,322 in 2006 for those on quadruple-or-more ART. The number of PLHIV using NHS services rose from 16,075 to 52,083 in 2006 and was projected to increase to 78,370 by 2013. Annual population cost rose from £104 million in 1997 to £483 million in 2006, with a projected annual cost between £721 and £758 million by 2013. When including community care costs, costs increased from £164 million in 1997, to £683 million in 2006 and between £1,019 and £1,065 million in 2013.

Conclusions

Increased number of PLHIV using NHS services resulted in rising UK population costs. Population costs are expected to continue to increase, partly due to PLHIV''s longer survival on ART and the relative lack of success of HIV preventing programs. Where possible, the cost of HIV treatment and care needs to be reduced without reducing the quality of services, and prevention programs need to become more effective. While high income countries are struggling to meet these increasing costs, middle- and lower-income countries with larger epidemics are likely to find it even more difficult to meet these increasing demands, given that they have fewer resources.     

Developmental changes in the responses of O2 uptake and ventilation to acutely declining O2 tensions in larval krill Meganyctiphanes norvegica

The effect of exposure to acutely declining oxygen tensions on O₂ uptake (M_O2) and ventilation has been investigated in different larval stages of Northern krill Meganyctiphanes norvegica (calytopis III/early furcilia I, late furcilia I, furcilia III and V). An ability to regulate M_O2 during acutely declining P_O2 began to appear about furcilia III (critical O₂ tension or P_c=15.4±0.73 kPa) and had improved by furcilia V (P_c=12.6±0.39 kPa). Hypoxia-related hyperventilation was achieved by an increase in pleopod (but not thoracic limb) activity (P_c∼11 kPa), a sensitivity which also appeared at, or just before, furcilia V even though an earlier stage (furcilia III) had a full compliment of functional setose pleopods. While this regulatory ability appeared as the gills were beginning to form, furcilia V is still early in gill ontogeny compared with adults. Preexposure to very moderate hypoxia (60% and 70% O₂ saturation) of furcilia III and V resulted in substantial mortality, but where it did not (furcilia V, 80% O₂ saturation), there was no effect of keeping krill at this P_O2 on either M_O2 or ventilation, suggesting that the development of respiratory regulation in M. norvegica is not open to environmental influence in the same way as for other crustaceans. We suggest that ontogeny of pleopod control provides furcilia V+ with both a stronger means of propulsion, allowing the ontogeny of DVM but also with an ability to regulate M_O2 during exposure to acutely declining P_O2s. The onset of respiratory regulation (furcilia V) preceded the onset of DVM (furcilia VI+). As pleopod ontogeny is associated intimately with the ontogeny of DVM and respiratory regulation, in the Gullmarsfjord this co-occurrence is fortuitous as krill can be required during DVM to migrate into hypoxic water which they are not equipped to deal with, in physiological terms, before furcilia V.     

Cholinergic and adrenergic tone on the heart of the Antarctic dragonfish, Gymnodraco acuticeps, living at sub-zero temperatures

Heart rate and ventral aortic blood pressures were recorded from the Antarctic dragonfish,Gymnodraco acuticeps, a member of the family Bathydraconidae. At −1.0 °C, the resting heart rate was 17.4 beats per minute and the ventral aortic pressure was 3.4 kPa. Cholinergic and adrenergic tone on the heart was determined by administration of the muscarine and ß-adrenoreceptor antagonists, atropine and sotalol, respectively. Neither antagonist influenced ventral aorta blood pressure; however, injection of atropine resulted in a significant increase in heart rate, and sotalol a decrease in heart rate. The cholinergic tone accounted for 30% of intrinsic heart rate and the adrenergic tone 26% of intrinsic heart rate. Comparison of these cardiac data with those for other teleosts from a wide range of thermal environments revealed no significant correlation for either cholinergic or adrenergic tone with body temperature (i.e. thermal independence); however, the resting and intrinsic heart rate of teleosts were strongly correlated with temperature.     

Consequences of competition on the reproduction and mortality of three species of terrestrial slugs

The interaction of three species of terrestrial slugs was studied in six field cages containing monocultures and 2-way combinations. A. columbianus and A. ater were non-aggressive species and L. maximus was highly aggressive during the summer. All three species were similar in body design and resource utilization. Reproduction (egg size, eggs/batch, number of batches, wet-weight productivity) and mortality were monitored through the 1977 season. L. maximus drastically reduced reproductive success of the non-aggressive slugs and increased their mortality. There were also significant interactions between the non-aggressive species. Compared to other invertebrates, the life history characteristics of A. columbianus are strongly K-selected and probably evolved through intraspecific exploitative competition in predictable, stable forest habitats. A. ater is best classified as a refuging r-selected species adapted to less predictable, unstable field environments. L. maximus appears to be α-selected and its overall design is suited to density-dependent regulation in fields.     

Kinetics of the helix-coil transition of a polypeptide with non-ionic side groups, derived from ultrasonic relaxation measurements.

Ultrasonic absorption and velocity dispersion curves have been measured in the temperature induced helix-coil transition range of poly-N5-(3-hydroxypropyl)-L-glutamine in a methanol/water mixture. The results clearly reflect an effect due to the kinetics of the conformational conversion. A practically single relaxation time is observed which passes through a maximum when plotted versus the degree of transition. This maximum occurs at definitely less than 50% helix as predicted for by the theory for the comparatively short chain length involved here. The results are discussed in relation to previous theoretical and experimental findings.     

Distribution and taxonomy of Pleistocene radiolarians from KH94-4-AMR-2PC core of the Southern Ocean region

This paper presents first comprehensive account of radiolarian taxa from the Pleistocene sequence of the Antarctic region. On the basis of 54 samples from the piston core KH94-4-AMR-2PC, 71 well-preserved radiolarian species were identified and illustrated. Their systematics, morphological variability and distribution in this Southern Ocean region are given and also compared with similar data available from other regions. Ten new taxa are described in detail but are yet to be formally named. This study provides a more extensive database and new taxa for comparative studies of other parts of the ocean sectors of the Antarctic region.     

Attitudes and sexual behaviours of unmarried people with HIV/AIDS living in the Niger Delta region of Nigeria

Background Increasing morbidity and mortality associated with HIV/AIDS may be attributable to the lifestyle of individuals. Appropriate sexual behaviour and lifestyle modification may be helpful strategies for prevention and control of HIV/AIDS in many countries.Aim The study was designed to assess the impact of attitudes and sexual behaviour on control of HIV/AIDS among unmarried people living with HIV/AIDS in Uyo, a community in the Niger Delta region of Nigeria.Method A total of 365 unmarried individuals living with HIV/AIDS were assessed at the HIV clinic of the University of Uyo Teaching Hospital. Attitudes and sexual behaviour were evaluated using the Attitude and Sexual Behaviour Questionnaire adapted from previous studies.Results Of the 365 individuals living with HIV/AIDS, 142 (38.9%) were male and 223 (61.1%) were female. The majority of the subjects were below 50 years of age. The mean ages (± SD) of men and women were 36.8 ± 3.9 and 29.2 ± 1.7 years, respectively. Sexual attitudes and behaviours were variable. There was no change in the partner''s reaction to sex for 28.9% of men and 27.8% of women, abstinence in 7.7% of men and 8.1% of women, and breakdown of the relationship with the partner for 4.9% of men and 7.2% of women. More women than men agreed to undergo testing after their partners had tested positive for HIV. Sexual activity was higher in women than men, with 4.9% of men and 10.3% of women reporting daily sexual intercourse, 16.2% of men and 15.7% of women reporting weekly intercourse, and occasional sexual intercourse being reported by 44.4% of both men and women. After testing positive, 58.4% of male partners and 56.9% of female partners were persuaded to use condoms during sexual intercourse.Conclusion This study has demonstrated unhealthy attitudes and sexual behaviour among individuals living with HIV/AIDS in the Niger Delta region of Nigeria. This can potentially limit efforts and investment in controlling HIV/AIDS in this region. Therefore there is a need to initiate concrete policies and programmes that would encourage people living with HIV/AIDS in the Niger Delta region to adopt a healthy lifestyle.     

Access to glacial and subglacial environments in the Solar System by melting probe technology

A key aspect for understanding the biological and biochemical environment of subglacial waters, on Earth or other planets and moons in the Solar system, is the analysis of material embedded in or underneath icy layers on the surface. In particular the Antarctic lakes (most prominently Lake Vostok) but also the icy crust of Jupiter’s moon Europa or the polar caps of Mars require such investigation. One possible technique to penetrate thick ice layers with small and reliable probes is by melting, which does not require the heavy, complex and expensive equipment of a drilling rig. While melting probes have successfully been used for terrestrial applications e.g. in Antarctic ice, their performance in vacuum is different and theory needs confirmation by tests. Thus, a vacuum chamber has been used to perform a series of melting tests in cold (liquid nitrogen cooled) water ice samples. The feasibility of the method was demonstrated and the energy demand for a space mission could be estimated. Due to the high energy demand in case of extraterrestrial application (e.g. Europa or polar caps of Mars), only heating with radioactive isotopes seems feasible for reaching greater depths. The necessary power is driven by the desired penetration velocity (approximately linearly) and the dimensions of the probe (proportional to the cross section). In comparison to traditional drilling techniques the application of a melting probe for exploration of Antarctic lakes offers the advantage that biological contamination is minimized, since the Probe can be sterilized and the melting channel freezes immediately after the probe’s passage, inhibiting exchange with the surface layers and the atmosphere. In order to understand the physical and chemical nature of the ice layers, as well as for analysing the underlying water body, a melting probe needs to be equipped with a suite of scientific instruments that are capable of e.g. determining the chemical and isotopic composition of the embedded or dissolved materials.     

Open-ocean barriers to dispersal: a test case with the Antarctic Polar Front and the ribbon worm Parborlasia corrugatus (Nemertea: Lineidae)

Open-ocean environments provide few obvious barriers to the dispersal of marine organisms. Major currents and/or environmental gradients potentially impede gene flow. One system hypothesized to form an open-ocean dispersal barrier is the Antarctic Polar Front, an area characterized by marked temperature change, deep water, and the high-flow Antarctic Circumpolar current. Despite these potential isolating factors, several invertebrate species occur in both regions, including the broadcast-spawning nemertean worm Parborlasia corrugatus. To empirically test for the presence of an open-ocean dispersal barrier, we sampled P. corrugatus and other nemerteans from southern South America, Antarctica, and the sub-Antarctic islands. Diversity was assessed by analyzing mitochondrial 16S rRNA and cytochrome c oxidase subunit I sequence data with Bayesian inference and tcs haplotype network analysis. Appropriate neutrality tests were also employed. Although our results indicate a single well-mixed lineage in Antarctica and the sub-Antarctic, no evidence for recent gene flow was detected between this population and South American P. corrugatus. Thus, even though P. corrugatus can disperse over large geographical distances, physical oceanographic barriers (i.e. Antarctic Polar Front and Antarctic Circumpolar Current) between continents have likely restricted dispersal over evolutionary time. Genetic distances and haplotype network analysis between South American and Antarctic/sub-Antarctic P. corrugatus suggest that these two populations are possibly two cryptic species.     

DTPA soil extractable and plant heavy metal concentrations with soil-added Cd treatments

Summary The numbers, weights, and ages of root nodules were determined in a homogeneous 6- to 7-year-old stand ofHippophaë rhamnoides in a coastal sand-dune area. Large variations in the number of nodules, which ranges from 30 to 281 per m² were found. Most of the nodules occurred between 10 and 60 cm below the soil surface. In the surface layer and lower than 60 cm only small numbers of nodules were present. It is concluded that relatively large samples have to be investigated to obtain an impression of the nodulation of a given stand and to permit a comparison of the contribution of dinitrogen fixation in different stands.Close correlation was found between nodule numbers and the age of the roots, young roots having the highest numbers. However, the wide variation in the number of nodules per square metre could not be explained solely by the age distribution of the roots. The possible role of some other factors is discussed. No relationship was found between the nodule weight and the age of the nodule. The mean dry weight of living nodule material was 5.3 g per m². Most nodules reached an age of up to 3 years. The significance of nodule decay for the distribution of the endophyte in the soil and in the process of nodule formation is discussed.     

Factors associated with self and informant ratings of the quality of life of people with dementia living in care facilities: a cross sectional study

Background

There is no consensus regarding the optimal approach to assessment of the quality of life of people with dementia. We undertook the present study to describe and determine the factors associated with ratings of the quality of life of a cohort of people with dementia living in a residential care facility.

Methodology/Principal Findings

351 people with dementia living in residential care facilities, and their staff and family informants participated in this cross sectional observational study. Quality of life was measured using self (Quality of Life in Alzheimer''s Disease [QoL-AD] scale), and informant (QoL-AD and Alzheimer''s Disease Related QoL Scale) reports. 226 people (64%) with dementia (median MMSE 17; 12–21) were able to self rate the QoL-AD scale and these subjects'' ratings were compared to ratings by staff and family. Both staff and family informant ratings of the QoL-AD underestimated self ratings (mean difference −7.8, 95% CI −8.8, −6.7 for staff rated QoL-AD; and mean difference −7.2, 95% CI −8.5, −6.0 for family rated QoL-AD). Self ratings of QoL were lower among people who were restrained, had fallen or had pain. Informant ratings of the QoL of the participants with dementia were consistently and significantly lower for people with severe cognitive impairment, who had fallen, had presence of neuropsychiatric symptoms, or where care giver distress was present. Documented restraint, reported pain and neuropsychiatric symptoms were independently associated with lower self rating of the QoL-AD in multivariate models. Cognitive impairment, case conferencing, hospitalizations and neuropsychiatric symptoms were found to be independently associated with staff rated ADRQL.

Conclusions

The majority of people with dementia living in residential care facilities can rate their own QoL. Informant ratings underestimate self ratings of QoL of people with dementia, and appear to be associated with factors which are not associated with self ratings.     

Bmo-miR-3377-5p down-regulates the Bombyx mori Sericin gene-1

MiRNAs are small non-coding molecules, which can regulate a huge number of genes. Based on bioinformatics analysis, we found a target site in the 3′UTR of BmSer-1 for binding bmo-miR-3377-5p. By using semi-quantitative RT-PCR, we detected that miR-3377-5p and BmSer-1 were both more highly expressed in the middle silk gland than in other tissues of 3-day-old fifth-instar Bombyx mori larvae, implying that there is a spatiotemporal condition for miR-3377-5p regulating on BmSer-1. To confirm this prediction, a BmSer-13′UTR recombinant luciferase reporter pGL3.0 [A3-luc-BmSer-1-3′UTR-SV40] and pri-bmo-miR-3377-5p expression pcDNA3.0 [ie1-egfp-pri-bmo-miR-3377-5p-SV40] were constructed and co-transfected into B. mori ovary cells (BmN cells). The results showed that miR-3377-5p suppressed the expression of BmSer-1 significantly (P < .001). When BmN cells were co-transfected by an artificial inhibitor together with a miR-3377-5p expression vector and a BmSer-1-3′UTR recombinant plasmid, BmSer-1 expression increased significantly (P < .05), indicating that the inhibitor was active against miR-3377-5p, and expression of BmSer-1 was recovered. Moreover, we injected miR-3377-5p expression plasmid and bmo-miR-3377-5p inhibitor into 3-day-old fifth-instar larvae. At 36 h post-injection, silk glands were collected for total RNA extraction. Quantitative RT-PCR analysis showed that miR-3377-5p down-regulated the expression of BmSer-1 in vivo, while there was no significant difference inhibitor treatment group compared with NC. Thus, we conclude that miR-3377-5p down-regulated the expression of BmSer-1. Our results provide insight for understanding the function of miRNAs and the regulation network of silk protein genes.