Aliens at home?

If we ponder how alien life might look like on other planets, we don''t have to go far, Simon Conway Morris argues, since life forms on Earth have already pushed life to the limits.When in 1609 Galileo first saw the moons of Jupiter, he must have been spellbound. I was certainly so enrapt when I saw Europa and her three companions strung like a line of jewels. Galileo may have appreciated the irony that my guide was a Jesuit priest, and the somewhat antiquated telescope we used was but a few yards from the Papal summer residence in Castel Gandolfo. Galileo prized open the door and before long, scientific imagination was fired by the prospect of innumerable inhabited worlds. As the centuries progressed, imagination raced ahead of facts, with the Moon optimistically colonized by Selenites, and Mars transformed by immense canals to supply the parched regions of a planet plunging into desertification. From this dying planet H.G. Wells propelled his aliens to terrorize southern England with immense tripods housing sinister octopoids.Now we might be closer to knowing if Wells was in any sense on the right track. The spectacular success in detecting extrasolar planets has produced a roster in excess of 450, and this technology potentially allows us to detect Earth-like planets. Even if many of the known planets are too large to be habitable and lie, for the most part, beyond the inferred ‘habitable zones'', before long we will get some clues as to how densely our galaxy is inhabited. The consensus points in two directions. First, life is a universal. Second, our biosphere will be of almost no use when it comes to comparisons. Let me draw your attention to a remarkably unappreciated fact: if you want to understand aliens, stay at home.Am I serious? After all it is already clear that extrasolar planetary systems are vastly different to our Solar System. Immense planets orbit their suns every few days, their surfaces far more torrid than that of Venus. Other planets most likely possess giant oceans, hundreds of kilometres deep. The diversity of moons and planets in our Solar System is a reminder of what may await us light years from Earth. Even among our neighbours, a case can be made for possible life in the clouds of Venus and Jupiter, the oceans of Europa and hydrocarbon lakes of Titan, and—with perennial optimism—in the permafrost of Mars. We might assume, therefore, that the range of environments available to life, its ‘habitation box'', is gigantic, and that Earth''s biosphere just nestles in one tiny corner. Oddly enough the evidence is exactly the opposite. Life on Earth has reached the limits of what is possible—anywhere.Temperature? The current limit on Earth is 122 °C. Plunging in the opposite direction the evidence is just as remarkable. At temperatures well below freezing, life carries on cheerfully. Even far beyond the eutectic, in which free water cannot form, organisms remain in a state of suspended animation with rates of damage and repair almost precisely matched. What of extreme desiccation? Evidently life has reached the limits of water activity. Entertainingly some of the hardiest forms are fungi that inhabit the weird alien world of Blue Stilton cheese. So, too, the bright colouration of salt pans is a familiar sight, and these osmotic extremes not only host rich microbial faunas but life that can flourish in the most bitter of brines. What of the extremes of pH—bleach versus battery acid? Once again, alkaliphiles and acidophiles disport themselves in ponds and streams that would have the Health and Safety officers in a state of panic. Pressure, either crushingly high or extremely attenuated? Life, of course, exists in the deepest oceanic trenches, but how much deeper might be viable? The weakest link seems to be the pressure sensitivity of the phospholipid membranes, suggesting that even on planets with titanic oceans life won''t survive much deeper than in the Mariana Trench. The same argument applies to the deep crust: at about 5 km the crushingly high pressures also coincide with the thermal limits imposed by the geothermal gradient. Shall we look to the skies? Clouds carry bacteria, but even at quite modest heights it seems to be accidental freight rather than a nebulous ecosystem.Terrestrial life has conquered nearly all of the ‘habitation box'' and its evolution begs so many questions. Are some forms, such as the hyperthermophiles, survivors from the Earth''s apocalyptic beginnings? Maybe, but most have clearly been reinvented several times. Getting to the limits of life isn''t that difficult, but how do extremophiles not only survive but flourish in these environments? Often the adaptations seem minor, which merely means they are more subtle than we might realize. What of the future? So far as the Earth is concerned it must cope with ever increasing solar luminosity: the last men will long predecease the last microbe. Possibly long before, we will engage in the first great galactic diaspora; but wherever our biologists journey they may find that life ‘out there'' got no further than the blue jewel that is Earth.     

Is Her Majesty at home?

When Queen Elizabeth is at home in Buckingham Palace, tradition has it that the Royal Standard is raised, so that all may know the fact. Although it is not crucial for most of us to know whether Her Majesty is home, it is in social insects. Endler et al. have recently shown how an ant queen signals her presence to her remote workers: she marks her eggs. This is significant because it provides insight into how queens maintain reproductive monopoly within their colonies.     

Does hospital at home for palliative care facilitate death at home? Randomised controlled trial

ObjectiveTo evaluate the impact on place of death of a hospital at home service for palliative care.DesignPragmatic randomised controlled trial.SettingFormer Cambridge health district.Participants229 patients referred to the hospital at home service; 43 randomised to control group (standard care), 186 randomised to hospital at home.InterventionHospital at home versus standard care.ResultsTwenty five (58%) control patients died at home compared with 124 (67%) patients allocated to hospital at home. This difference was not significant; intention to treat analysis did not show that hospital at home increased the number of deaths at home. Seventy three patients randomised to hospital at home were not admitted to the service. Patients admitted to hospital at home were significantly more likely to die at home (88/113; 78%) than control patients. It is not possible to determine whether this was due to hospital at home itself or other characteristics of the patients admitted to the service. The study attained less statistical power than initially planned.ConclusionIn a locality with good provision of standard community care we could not show that hospital at home allowed more patients to die at home, although neither does the study refute this. Problems relating to recruitment, attrition, and the vulnerability of the patient group make randomised controlled trials in palliative care difficult. While these difficulties have to be recognised they are not insurmountable with the appropriate resourcing and setting.

Key messages

• Terminally ill patients allocated to hospital at home were no more likely to die at home than patients receiving standard care
• Although the subsample of patients actually admitted to hospital at home did show a significant increase in likelihood of dying at home, whether this was due to the service itself or the characteristics of patients admitted to hospital at home could not be determined
• The need to balance ideal research design against the realities of evaluation of palliative care had the effect that the trial achieved less statistical power than originally planned
• Particular problems were that many patients failed to receive the allocated intervention because of the unpredictable nature of terminal illness, inclusion of other service input alongside hospital at home, and the wide range of standard care available
• The trial illustrated problems associated with randomised controlled trials in palliative care, none of which are insurmountable but which require careful consideration and resourcing before future trials are planned

     

Niche shift in invasive species: is it a case of “home away from home” or finding a “new home”?

In recent years, there has been a rather acrimonious debate on matters concerning the biology of invasive species, some as fundamental as the definition and what constitutes an invasive species. However, an abiding commonality of all invasive species is the fact that they have all moved away from their native ranges to newer and often non-native ranges. In plants, Lantana camara has shifted from its native South American range distribution to most other parts of the world. In animals, the African giant snail has dispersed from Africa to most parts of Asia. What do such niche shifts signify about the nature and quality of the habitats to which the invasive species have moved? In this paper, using the classical niche paradigm, we analyse if niche shifts of thirty-three of the world’s top invasive species constitute just moving from one habitat to another similar habitat somewhere on the earth (home away from home) or that they have moved to totally new habitats (different from their native home). Surprisingly, our results show that for 90% of the world’s top invasive species, movements have been largely restricted to homes away from home, rather than into alien homes. This clearly indicates the potential inertia that species might face in moving out of their fundamental niche. We discuss these results in the context of the overall debate on invasion biology and how niche conservatism may have played a role in dampening the rates of invasion.

     

Are cultured human myotubes far from home?

Satellite cells can be isolated from skeletal muscle biopsies, activated to proliferating myoblasts and differentiated into multinuclear myotubes in culture. These cell cultures represent a model system for intact human skeletal muscle and can be modulated ex vivo. The advantages of this system are that the most relevant genetic background is available for the investigation of human disease (as opposed to rodent cell cultures), the extracellular environment can be precisely controlled and the cells are not immortalized, thereby offering the possibility of studying innate characteristics of the donor. Limitations in differentiation status (fiber type) of the cells and energy metabolism can be improved by proper treatment, such as electrical pulse stimulation to mimic exercise. This review focuses on the way that human myotubes can be employed as a tool for studying metabolism in skeletal muscles, with special attention to changes in muscle energy metabolism in obesity and type 2 diabetes.     

How does Trichinella spiralis make itself at home?

The nurse cell-parasite complex of Trichinella spiralis is unlike anything else in Nature. It is derived from a normal portion of striated skeletal muscle cell and develops in a matter of 15 to 20 days after the larva invades that cell type. What are the molecular mechanisms at work that result in this unique relationship? Here, Dickson Despommier presents a hypothesis to account for its formation, in which secreted tyvelosylated proteins of the larva play a central role. These proteins are always present in the intracellular niche of the larva from Day 7 after infection and may be responsible for redirecting host genomic expression, leading to nurse cell formation.     

CEUSPEC — a computerized system for fetal home telemetry

We have developed a computerized system whereby the fetal heart rate can be recorded telemetrically from patients' homes, transmitted over conventional public telephone lines, and then computer-processed in real time in the obstetric unit.     

The host cytosol: front-line or home front?

Intracellular pathogens replicate in modified vacuolar compartments or in the cytosol of host cells. Many pathogenic bacterial species have evolved to modify the host vacuolar environment, but little is known about the mammalian cytosol as a medium for bacterial growth. Recent studies indicate that the cytosol is restrictive for the growth of bacteria other than cytosolic pathogens in contrast to earlier research that provided evidence that any bacteria with access to the cytosol can replicate there. Comparison of these studies suggests that the cytosolic contents of various host cell types can be differentially permissive for bacterial growth, and that both host and bacterial factors are important in determining the ability of particular bacteria to replicate in the cytosol.     

Which physicians make home visits and why? A survey

BACKGROUND: Recent changes in the North American health care system and certain demographic factors have led to increases in home care services. Little information is available to identify the strategies that could facilitate this transformation in medical practice and ensure that such changes respond adequately to patients'' needs. As a first step, the authors attempted to identify the major factors influencing physicians'' home care practices in the Quebec City area. METHODS: A self-administered questionnaire was sent by mail to all 696 general practitioners working in the Quebec City area. The questionnaire was intended to gather information on physicians'' personal and professional characteristics, as well as their home care practice (practice volume, characteristics of both clients and home visits, and methods of patient assessment and follow-up). RESULTS: A total of 487 physicians (70.0%) responded to the questionnaire, 283 (58.1%) of whom reported making home visits. Of these, 119 (42.0%) made fewer than 5 home visits per week, and 88 (31.1%) dedicated 3 hours or less each week to this activity. Physicians in private practice made more home visits than their counterparts in family medicine units and CLSCs (centres locaux des services communautaires [community centres for social and health services]) (mean 11.5 v. 5.8 visits per week), although the 2 groups reported spending about the same amount of time on this type of work (mean 5.6 v. 5.0 hours per week). The proportion of visits to patients in residential facilities or other private residences was greater for private practitioners than for physicians from family medicine units and CLSCs (29.7% v. 18.9% of visits), as were the proportions of visits made at the patient''s request (28.0% v. 14.2% of visits) and resulting from an acute condition (21.4% v. 16.0% of visits). The proportion of physicians making home visits at the request of a CLSC was greater for those in family medicine units and CLSCs than for those in private practice (44.0% v. 11.3% of physicians), as was the proportion of physicians making home visits at the request of a colleague (18.0% v. 4.5%) or at the request of hospitals (30.0% v. 6.8%). Physicians in family medicine units and CLSCs did more follow-ups at a frequency of less than once per month than private practitioners (50.9% v. 37.1% of patients), and they treated a greater proportion of patients with cognitive disorders (17.2% v. 12.6% of patients) and palliative care needs (13.7% v. 8.6% of patients). Private practitioners made less use of CLSC resources to assess home patients or follow them. Male private practitioners made more home visits than their female counterparts (mean 12.8 v. 8.3 per week), although they spent an almost equal amount of time on this activity (mean 5.7 v. 5.2 hours per week). INTERPRETATION: These results suggest that practice patterns for home care vary according to the physician''s practice setting and sex. Because of foreseeable increases in the numbers of patients needing home care, further research is required to evaluate how physicians'' practices can be adapted to patients'' needs in this area.     

Which population density affects home ranges of co-occurring rodents?

Animal space use patterns can be affected by the intra- and interspecific density of individuals competing for resources, with home ranges generally decreasing with increasing population density. By applying spatially explicit capture–recapture models implemented in the R package secr, we study whether home ranges of co-occurring yellow-necked mice, Apodemus flavicollis, and bank voles, Myodes glareolus, are related to population density of (a) conspecifics (intraspecific density), (b) the other sympatric species, A. flavicollis or M. glareolus (interspecific density), or (c) total rodent density (A. flavicollis plus M. glareolus). Home ranges of both species were negatively related to intraspecific population density, and were not related to interspecific density or total rodent density. Given that rodents tend to reduce home ranges if resources are abundant, this pattern may merely result from the higher abundance of resources generally associated with high density populations, if the two species were responding to different subsets of resources. However, intraspecific density could directly reduce home ranges, because conspecifics are more likely to interfere with each other due to the overlapping of space use patterns. Therefore, results suggest complementary space or resource use patterns between species, with consequent weak competition and niche differentiation. Across several years and population densities, home ranges of the two co-occurring rodents thus appear to be affected by conspecifics only, suggesting that the two species may coexist in the study area owing to limited space or resource use overlap.     

Deciding on a new home: how do honeybees agree?

A swarm of honeybees (Apis mellifera) is capable of selecting one nest-site when faced with a choice of several. We adapt classical mathematical models of disease, information and competing beliefs to such decision-making processes. We show that the collective decision may be arrived at without the necessity for any bee to make any comparison between sites.     

Early home learning environment predicts children’s 5th grade academic skills

We examined whether the early learning environment predicts children’s 5th grade skills in 2,204 families from ethnically diverse, low-income backgrounds; tested the mediating roles of children’s pre-kindergarten school-related skills and later learning environment; and asked whether lagged associations generalize across White, Black, Hispanic English-speaking, and Hispanic Spanish-speaking samples. Children’s early learning environment comprised measures of literacy activities, the quality of mothers’ engagements with children, and learning materials assessed at 14 months, 2 and 3 years, and at pre-kindergarten; learning environments were again assessed in 5th grade. At pre-kindergarten and in 5th grade, children were assessed on pre-academic and academic skills respectively. Early learning environments predicted children’s 5th grade academic skills, and children’s pre-kindergarten skills and 5th grade learning environment mediated longitudinal associations. The early learning environment supports the emergence of pre-academic skills that are stable into early adolescence, and pathways generalize across ethnic/racial groups.     

Daily movements and home range in mithrax spinosissimus (Majidae,Decapoda)†

Individuals of the spider crab Mithrax spinosissimus living in a canal in the Florida Keys were marked and their movements followed over a four‐month period. Individual home range size, extent of daily movement, and extent of day‐night movement were calculated. Although males and females moved similar distances when they did move from one crevice to another, males re‐located more frequently. There was no correlation between animal size and any measure of movement. Extent of daily movement was inversely correlated with spider crab density, especially for female crabs.     

Changes in physical activity and fitness after 3 months of home Wii Fit™ use

The purpose of this study was to examine changes in physical activity and fitness variables in members of 8 volunteer families after 3 months of home use of the Wii Fit? interactive video game. Pre and postintervention measurements were obtained from 21 subjects relative to physical activity (5 days of accelerometry), aerobic fitness (graded treadmill test), muscular fitness (push-ups), flexibility (sit-and-reach test), balance (composite equilibrium score), and body composition (body mass index and % body fat). Use characteristics of the Wii Fit? device were also determined. A series of 2 (age group) × 2 (time) repeated measures analyses of variance were conducted to assess changes over time and between adults and children. Three months of home Wii Fit? use revealed no significant age group × time interactions or main effects of group or time for daily physical activity, muscular fitness, flexibility, balance, or body composition. An age group × time interaction (p = 0.04) was observed in peak VO2 (ml·kg(-1)·min(-1)) with children displaying a significant (p = 0.03) increase after 3 months of Wii Fit? use, whereas adults showed no significant (p = 0.50) change. Daily Wii Fit? use per household declined by 82% (p < 0.01) from 21.5 ± 9.0 min·d(-1) during the first 6 weeks to 3.9 ± 4.0 min·d(-1) during the second 6 weeks. Most measures of health-related fitness in this exploratory study remained unchanged after 3 months of home use of the popular Wii Fit? whole-body movement interactive video game. Modest daily Wii Fit? use may have provided insufficient stimulus for fitness changes.     

A possible home for a bizarre Carboniferous animal: is Typhloesus a pelagic gastropod?

By contrast to many previously enigmatic Palaeozoic fossils, the Carboniferous metazoan Typhloesus has defied phylogenetic placement. Here, we document new features, including possible phosphatized muscle tissues and a hitherto unrecognized feeding apparatus with two sets of ca 20 spinose teeth whose closest similarities appear to lie with the molluscan radula. The ribbon-like structure, located well behind the mouth area and deep into the anterior part of the body, is interpreted as being in an inverted proboscis configuration. Gut contents, mostly conodonts, in the midgut area demonstrate that Typhloesus was an active predator. This animal was capable of propelling itself in the water column using its flexible body and a prominent posterior fin. The affinity of Typhloesus as a pelagic mollusc remains problematic but may lie more closely with the gastropods. Heteropod gastropods share with Typhloesus an active predatory lifestyle and have a comparable general body organization, albeit they possess characteristic aragonitic shells and their origins in the Jurassic post-date Typhloesus. Typhloesus may represent an independent radiation of Mid-Palaeozoic pelagic gastropods.