Evolutionary adaptation of a reflex system: sensory hysteresis counters muscle ‘catch’ tension

Summary The metathoracic femoral chordotonal organ is a receptor of the locust,Schistocerca, hindleg that encodes the angle of the femoro-tibial joint. However, the discharge of the organ shows considerable hysteresis, in that there is a substantial decline in the level of afferent firing when the tibia is moved and then returned to its initial position. Similar hysteresis is also seen in some joint receptors and interneurons of other invertebrates and vertebrates. When the chordotonal organ is stimulated in freely moving locusts, mimicking sudden changes in joint angle, reflex discharges can be elicited in the tibial extensor muscle that resist apparent joint movement and also show similar hysteresis. This pattern of motoneuron activity is demonstrated to potentially function to eliminate residual, catch muscle tensions that result from increases in motoneuron firing frequency. This adaptation could also serve to produce accurate load compensation.     

Genetic and biochemical studies on perchloroethylene ‘in vitro’ and ‘in vivo’

Perchloroethylene (PCE) was tested in a diploid strain (D7) of the yeast Saccharomyces cerevisiae in suspension tests with and without a mammalian microsomal activation system (S9) and ‘in vivo’ by the intrasanguineous host-mediated assay. In addition, enzyme alteration studies were performed in mice non-pretreated or pretreated with phenobarbital + β-naphthoflavone. PCE did not induce any genetic effect either ‘in vitro’ or ‘in vivo’. In the suspension test, PCE was more toxic without metabolic activation and less toxic with mammalian microsomal activation. The enzymatic determinations showed an increase of the aminopyrine demethylase activity and of the level of cytochrome P-450.     

Faith on Trial: Blasphemy and ‘Lawfare’ in Indonesia

ABSTRACT

This article develops the argument that blasphemy trials occupy a pivotal role in ‘religion-making’ in post-1998 Indonesia. Examining a blasphemy trial on the island of Lombok in 2010, I argue that the process of democratisation has given civilian actors more opportunity to engage Indonesia’s blasphemy law, a process analysed in terms of ‘lawfare’. Examining the interplay of legal regulation and the campaign against ‘deviant’ religion launched by conservative Muslim groups, the article tracks the affective consequences of this regulation, showing how the blasphemy law inspires civilians to investigate suspected cases of heresy. While blasphemy trials purportedly protect religion from insult and foster religious order, this article argues that religion lawfare breeds suspicion and divisions among citizens.     

Morphology and accessibility of the ‘transverse’ tubular system in frog sartorius muscle after glycerol treatment

Summary Sartorius muscles were exposed to a hypertonic Ringer's fluid containing 400mm glycerol and subsequently returned to normal Ringer's fluid. Employing lanthanum as an extracellular marker and after suitable preparation, sections of muscle fibers were examined with an electron-microscope. Extensive alteration in transverse tubular morphology occurs after glycerol treatment. The number of sites at the Z line level usually containing complete triads decreases by about two-thirds. In about half of the sites with altered morphology no transverse tubules were present, while in the other half the sites were completely empty. Fibers at all depths in glycerol-treated muscles were equally affected. The remnants of the transverse tubules which remain were not very accessible to extracellular lanthanum. Estimates based on measurements of the presence or absence of lanthanum indicate that glycerol treatment disconnects 90% of the transverse tubules from the external solution. The remaining tubules connected to the external solution are largely but not entirely located in a surface layer of about one-tenth the fiber radius in depth.     

The ‘Psychic Surgeon’ and the schizophrenic patient: Crisis in a ‘Medicodrama’

This paper is concerned with a Filipino psychic surgeon confronted by a particularly challenging case of a kind perhaps unprecedented in his practice. The paper describes and analyzes how the practitioner modified his usual clinical performance and adapted his actions to demands of an extremely difficult situation. The case is viewed in wider perspective relative to the significance of performative acts of healing in a pluralistic medical setting.     

Effects of β₂-agonists on force during and following anoxia in rat extensor digitorum longus muscle

Electrical stimulation of isolated muscles may lead to membrane depolarization, gain of Na(+), loss of K(+) and fatigue. These effects can be counteracted with β(2)-agonists possibly via activation of the Na(+)-K(+) pumps. Anoxia induces loss of force; however, it is not known whether β(2)-agonists affect force and ion homeostasis in anoxic muscles. In the present study isolated rat extensor digitorum longus (EDL) muscles exposed to anoxia showed a considerable loss of force, which was markedly reduced by the β(2)-agonists salbutamol (10(-6) M) and terbutaline (10(-6) M). Intermittent stimulation (15-30 min) clearly increased loss of force during anoxia and reduced force recovery during reoxygenation. The β(2)-agonists salbutamol (10(-7)-10(-5) M) and salmeterol (10(-6) M) improved force development during anoxia (25%) and force recovery during reoxygenation (55-262%). The effects of salbutamol on force recovery were prevented by blocking the Na(+)-K(+) pumps with ouabain or by blocking glycolysis with 2-deoxyglucose. Dibutyryl cAMP (1 mM) or theophylline (1 mM) also improved force recovery remarkably. In anoxic muscles, salbutamol decreased intracellular Na(+) and increased (86)Rb uptake and K(+) content, indicating stimulation of the Na(+)-K(+) pumps. In fatigued muscles salbutamol induced recovery of excitability. Thus β(2)-agonists reduce the anoxia-induced loss of force, leading to partial force recovery. These data strongly suggest that this effect is mediated by cAMP stimulation of the Na(+)-K(+) pumps and that it is not related to recovery of energy status (PCr, ATP, lactate).     

‘Chancing on a spectacle:’ co-occurring animal migrations and interspecific interactions

Migrations of diverse wildlife species often converge in space and time, with their journeys shaped by similar forces (i.e. geographic barriers and seasonal resources and conditions); we term this ‘co-migration’. Recent studies have illuminated multi-speciesmigrations by land and sea including the simultaneous movements of numerous insects, birds, bats and of fish invertebrates marine predators. Beyond their significance as natural wonders, species with overlapping migrations may interact ecologically, with potential effects on population and community dynamics. Direct and indirect ecological interactions (including predation and competition) between migrant species remain poorly understood, in part because migration is the least-studied phase of animals’ annual cycles. To address this gap, we conducted a literature review to examine whether animal migration studies incorporate multiple species and to what extent they investigate interspecific interactions between co-migrants. Following a key word search, we read all migration research papers in 23 relevant peer-reviewed journals during 2008–2017. Thirty percent of animal migration papers reported two or more species with coinciding migrations, suggesting that co-migrations are common, although few studies investigated or discussed these mixed-species migrations further. Synthesizing these, we present examples and describe five types of ecological interactions between migrating species, including predator–prey, host–parasite and commensal relationships. Considering migratory animals as interacting with migrant communities will enhance understanding of the drivers of migration and could improve predictions about wildlife responses to global change. Further research focused on multi-species migrations could also inform conservation efforts for migratory animal populations, many of which are declining or shifting, with unexplored consequences for other co-migratory species.     

‘Life after last orders’: microbiology as a career

The 2003 conference of the International Biodegradation and Biodeterioration Society (www.biodeterioration. org) and the International Biodegradation Research Group (www.ibrg.org), was held last September at the Manchester Metropolitan University. The conference, ‘Management and Control of Undesirable Microorganisms’, followed the usual format of lectures, questions, posters and social events, but an additional event was staged for younger society members. Funding from FEMS, the Federation of European Microbiology Societies, in the form of a Young Scientists Grant, enabled the attendance of delegates from across Europe including the Czech Republic, Latvia, Germany, Russia, Uzbekistan and the UK. These delegates, and the rest of the conference, were invited to a workshop entitled ‘Life after Last Orders’, where some of the slightly older members of the Society described their career paths. Informal 5–10 minute presentations were followed by question/answer sessions, which also included some interesting contributions from the floor. The session was chaired by the two youngest members of IBBS Council, Kathryn Whitehead, a PhD student at MMU, and Chris van der Gast, from the University of Oxford Centre for Environmental Biotechnology. The following narratives describe the career paths of two ‘experienced’ microbiologists! It was fascinating to hear how the careers of one's peers had developed.     

Is titin a ‘winding filament’? A new twist on muscle contraction

Recent studies have demonstrated a role for the elastic protein titin in active muscle, but the mechanisms by which titin plays this role remain to be elucidated. In active muscle, Ca(2+)-binding has been shown to increase titin stiffness, but the observed increase is too small to explain the increased stiffness of parallel elastic elements upon muscle activation. We propose a 'winding filament' mechanism for titin's role in active muscle. First, we hypothesize that Ca(2+)-dependent binding of titin's N2A region to thin filaments increases titin stiffness by preventing low-force straightening of proximal immunoglobulin domains that occurs during passive stretch. This mechanism explains the difference in length dependence of force between skeletal myofibrils and cardiac myocytes. Second, we hypothesize that cross-bridges serve not only as motors that pull thin filaments towards the M-line, but also as rotors that wind titin on the thin filaments, storing elastic potential energy in PEVK during force development and active stretch. Energy stored during force development can be recovered during active shortening. The winding filament hypothesis accounts for force enhancement during stretch and force depression during shortening, and provides testable predictions that will encourage new directions for research on mechanisms of muscle contraction.     

Lipid,phenol and carotenoid changes in ‘Bianca’ grapevine leaves after mechanical wounding: a case study

Metabolic changes can occur in plants in response to abiotic stress. Extensive use of leaf discs (mechanical wounding) in studies regarding the effect on the biochemical response of the grapevine to different types of biotic stress makes it necessary to understand metabolic perturbation after injury. In this study, we investigate how mechanical wounding can affect the metabolism of grapevine leaf tissue using Bianca variety as case study. Two sizes of leaf discs (1.1 and 2.8 cm in diameter) were excised from leaves, and phenol, lipid and carotenoid perturbation were investigated 0, 6, 12, 24, 48, 96 and 120 h post cutting. In our study, we found an accumulation of molecules belonging to stilbenoid and stilbene classes such as trans-resveratrol, trans-piceide, Z-miyabenol C, E-cis-miyabenol C and ampelopsin D + quadrangularin A after abiotic stress. The increase in fatty acids such as linoleic acid, linolenic acid and oleic + cis-vaccenic acid during the first 12 h after injury, followed by a return to basal level, allowed us to surmise their role in response to abiotic stress, in particular to mechanical wounding in grapevine leaves. Different-sized discs caused a different response to the tissue, with a higher accumulation in 1.1-cm-diameter discs, especially of phenol compounds. The results of this work can be used to better understand metabolic changes due to biotic stress, having previous knowledge about the perturbation caused by abiotic stress.     

Aboriginal ‘Difference’ and ‘Autonomy’ Then and Now: Four Decades of Change in a Western Desert Society

In just a few decades, Aboriginal people living near Australia's Western Desert fringe have experienced an extraordinarily intense trajectory of change: from a highly autonomous nomadic existence, through ‘first contacts’, the pastoral and mission frontiers, the devastating impacts of alcohol and of Western lifestyle diseases, the outstation movement, resource exploration and mining, a long but largely successful struggle for native title, and much else. In this paper, notions of ‘difference’ and ‘autonomy’ are used to explore these transformations. The situation among the Mardu is here linked to the gulf between government policies and lived Aboriginal experience. If the self‐management thrust of 1970s policies achieved partial restoration of Aboriginal autonomy, recent Federal Government policies are intent on intervention to reduce difference and claw back some of that autonomy. Their determination to force Aboriginal people out of their ‘dysfunctional’ ‘cultural museums’ (homeland settlements) and into greater economic engagement ignores the crucial underpinnings of security and identity among remote Aborigines. The retention of difference, albeit at considerable social cost and entrenched disadvantage, is still strongly preferred by Mardu to the kinds of engagement with the dominant society that not only assault their sense of self but also threaten to overwhelm whatever autonomy remains to them.     

‘Fine’ and ‘coarse’ mycorrhizal fungi on red clover plants in acid soils: Root colonization and plant responses

Three sterilized acid soils were inoculated with inocula of vesicular-arbuscular mycorrhizal fungi. Soils were limed and/or P fertilized to produce different fertility levels. Most inocula consisted of mixtures of fine + coarse type endophytes. Red clover (Trifolium pratense L.) was seeded in pots and grown in a glasshouse for 4 months. Root colonization by VAM fungi, the relative infection byGlomus tenue compared to that by coarse VAM fungi and the effect of inoculation on red clover growth and mineral nutrition (P, K, Ca and Mg) were studied. Spores were also checked and tentatively identified.Results showed that root colonization by VAM fungi was higher than 50% in most cases, the lower values being found in the soil with the highest P content. Inocula containingG. mosseae + G. tenue infected plant roots only in limed (pH>5.7) soils. A study of the relative colonization by fine and coarse endophytes showed that the competitive ability againstG. tenue followed the orderG. fasiculatum > G. mosseae > G. epigaeum > G. macrocarpum, although soil properties and fertility were crucial factors.Glomus lacteum was tentatively identified in two of the three experimental soils. The inoculum in whichGlommus tenue was most infective was also the most efficient in improving plant growth and nutrient uptake. The effect of inoculation on P and Mg uptake followed a similar pattern.     

A comment on ‘ethnic discrimination in employment and housing’

This article investigates Los Angeles employers' attitudes towards African American and immigrant Latino low-skill workers. Using 145 in-depth interviews of employers in four industries, I find that a central concern of employers of low-skill jobs is control at the workplace, and employers consequently seek workers whom they perceive as manageable and pliable. As such, the most salient component of employers' attitudes towards African American and immigrant Latino low-skill workers is their perception that the manageability and pliability of workers vary by race, nativity and gender. I also link employers' micro-level attitudes to broader societal level ideologies about race and opportunity. I find that employers' attitudes were embedded within an ideology of individualism, as exemplified by the idea of the 'American Dream', and reflected the growing belief that race-based claims are illegitimate.     

Patronage in a Holy Place: Preliminary research notes on a ‘parallel structure’ in a Yugoslav pilgrimage centre*

Eric Wolf has argued that the study of patron‐client relations and other ‘parallel structures’ may be useful for furthering our understanding of complex societies. As for political patronage, Wolfs suggestion has been taken to heart. As far as religion is concerned, his suggestion has barely met with any response at all. Data obtained from a Yugoslav peasant community seem to indicate that Wolf s proposition is applicable to the religious field as well. In Medjugorje, a pilgrimage centre in Bosnia‐Hercegovina, a patronage network has evolved around a small group of young local seers. The relations with the ‘official’, clergy‐run Marian devotion are rather strained. This article explores the dynamics of that parallel structure of the institutional Church, and discusses if and in what respects this visionary‐centered patronage network differs from patron‐client configurations in the political field.     

Algae extracts and methyl jasmonate anti-cancer activities in prostate cancer: choreographers of ‘the dance macabre’

Background

GSAO (4-(N-(S-glutathionylacetyl)amino) phenylarsonous acid) and PENAO (4-(N-(S-penicillaminylacetyl)amino) phenylarsonous acid) are tumour metabolism inhibitors that target adenine nucleotide translocase (ANT) of the inner-mitochondrial membrane. Both compounds are currently being trialled in patients with solid tumours. The trivalent arsenical moiety of GSAO and PENAO reacts with two matrix facing cysteine residues of ANT, inactivating the transporter. This leads to proliferation arrest and death of tumour and tumour-supporting cells.

Results

The two reactive ANT cysteine residues have been identified in this study by expressing cysteine mutants of human ANT1 in Saccharomyces cerevisiae and measuring interaction with the arsenical moiety of GSAO and PENAO. The arsenic atom of both compounds cross-links cysteine residues 57 and 257 of human ANT1.

Conclusions

The sulphur atoms of these two cysteines are 20 Å apart in the crystal structures of ANT and the optimal spacing of cysteine thiolates for reaction with As (III) is 3-4 Å. This implies that a significant conformational change in ANT is required for the organoarsenicals to react with cysteines 57 and 257. This conformational change may relate to the selectivity of the compounds for proliferating cells.     

‘Hemiepiphyte’: a confusing term and its history

Background and Scope

Over more than 120 years of scientific study since Schimper''s seminal work, the recognized categories of structurally dependent plants have changed several times. Currently, ignoring parasitic mistletoes, it is usual to distinguish four functional groups: (1) true epiphytes; (2) primary hemiepiphytes; (3) secondary hemiepiphytes; and (4) climbing plants, i.e. lianas and vines. In this Viewpoint, it is argued that the term secondary hemiepiphytes (SHs) is misleading, that its definition is hard to impossible to apply in the field and, possibly causally related to this conceptual problem, that the use of this category in field studies is inconsistent, which now hampers interpretation and generalization.

Conclusions

Categories will frequently fail to capture gradual biological variation, but terms and concepts should be as unambiguous as possible to facilitate productive communication. A detailed analysis of the conceptual problems associated with the term SH and its application in scientific studies clearly shows that this goal is not fulfilled in this case. Consequently, the use of SH should be abandoned. An alternative scheme to categorize structurally dependent flora is suggested.