How many and which ant species are being accidentally moved around the world?

Human transportation facilitates the dispersal of exotic ants, but few studies have quantified the magnitude and geography of these movements. We used several non-parametric indices to estimate the number of species successfully introduced to or established in new regions. We also compared their source biogeographic realms to assess the importance of geographical origin in determining the likelihood of establishment after introduction. Occurrence data on exotic ants derive from studies of three temperate regions. Our results suggest that the numbers of introduced or established ants may be much larger than the numbers so far documented. Ants introduced or established in new regions tend to arrive from the same or neighbouring realms, as would be expected if exotic species tend to match climates and if arrival/establishment is dependent upon higher trade rates from neighbouring countries.     

Left and right in the amphibian world: which way to develop and where to turn?

The last decade has seen a dramatic increase in studies on the development, function and evolution of asymmetries in vertebrates, including amphibians. Here we discuss current knowledge of behavioral and anatomical asymmetries in amphibians. Behavioral laterality in the response of both adult and larval anurans to presumed predators and competitors is strong and may be related, respectively, to laterality in the telencephalon of adults and the Mauthner neurons of tadpoles. These behavior lateralities, however, do not seem to correlate with visceral asymmetries in the same animals. We briefly compare what is known about the evolution and development of asymmetry in the structure and function of amphibians with what is known about asymmetries in other chordate and non-chordate groups. Available data suggest that the majority of asymmetries in amphibians fall into two independent groups: (1) related to situs viscerum and (2) of a neurobehavioral nature. We find little evidence linking these two groups, which implies different developmental regulatory pathways and independent evolutionary histories for visceral and telencephalic lateralizations. Studies of animals other than standard model species are essential to test hypotheses about the evolution of laterality in amphibians and other chordates.     

Hybrid larch heterosis: for which traits and under which genetic control?

RCD1 is a member of the plant-specific SRO protein family. Several SRO genes have been functionally identified in the regulation of abiotic stresses in Arabidopsis and other plant species. However, the function of SROs is largely unknown in apple (Malus×domestica). In this study, six MdSRO-encoding genes were isolated, categorized into two types and mapped to six chromosomes. The phylogenetic analysis demonstrated that the sequences of the AtSRO and MdSRO proteins are highly conserved. Subsequently, expression analysis showed that MdSRO genes had different expression profiles in different tissues and in response to various stresses. Finally, MdRCD1 was isolated for functional identification. The results showed that resistance to oxidation stress in apple calli was enhanced by MdRCD1 overexpression and weakened by MdRCD1 suppression. MdRCD1 also played a crucial role in the regulation of ROS homeostasis in transgenic apple calli and Arabidopsis. Ectopic expression of MdRCD1 significantly enhanced resistance to salt and oxidative stresses in transgenic lines. In addition, MdRCD1 also enhanced drought tolerance due to its influence on stomatal opening. Based on these results, we conclude that MdRCD1 is an important regulator in abiotic stress response.

     

An integrin chicken and egg problem: which comes first, the extracellular matrix or the cytoskeleton?

Integrins have the ability to organise macromolecular structures both inside and outside the cell. Analysis of integrin function in the developing embryos of worms and flies suggests that, although the extracellular matrix directs integrins to organise intracellular proteins, the cytoskeleton may have the first word.     

The good,the bad,and the ugly: which Australian terrestrial mammal species attract most research?

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Coexistence of competing parasitoids: which is the fugitive and where does it hide?

Most insects harbour a community of parasitoids that coexist in spite of competition for resources. One potential mechanism for coexistence of competitors is a tradeoff between dispersiveness and local competitive ability. Here we present a study of competition between the specialized parasitoids Hyposoter horticola and Cotesia melitaearum sharing the Glanville fritillary butterfly, Melitaea cinxia . Within one host generation, the parasitoid larvae interact inside the host during each of the three C. melitaearum generations. We founds that in the summer when the host is small, the solitary H. horticola is the superior competitor, suppressing the gregarious C. melitaearum as eggs or small larvae. When multiparasitism occurs in the autumn the two parasitoid species engage in physical combat and C. melitaearum is favoured. Finally, a previous study showed that in the third C. melitaearum generation the univoltine H. horticola grows quickly during its final instar, excluding young C. melitaearum simply through limited time and resources. We found that contrary to expectations of the evolution of gregariousness, C. melitaearum , which lives in sibling groups, has biting mandibles in the first instar while the solitary H. horticola has suctorial mouthparts. Previous studies suggest that the two parasitoids co-exist because H. Horticola is dispersive and C. melitaearum is a strong local competitor. However, putting together the results of this experiment and out recent understanding of the adult wasp foraging behaviours and large scale population dynamics, we conclude that H. horticola is both a superior local competitor and more dispersive than C. melitaearum . Cotesia melitaearum has no impact on the population dynamics of H. horticola , persisting as a fugitive using a small fraction the larvae left unparasitized by H. horticola .     

Identity of esterase-22 and egasyn,the protein which complexes with microsomal β-glucuronidase

Recent experiments have demonstrated that egasyn not only sequesters -glucuronidase in microsomes by forming high molecular weight complexes with -glucuronidase, but also has carboxyl esterase activity. We have found several new phenotypes of egasyn-esterase after electrophoresis and isoelectric focusing of liver homogenates and purified egasyn of inbred and wild mouse strains. Several phenotypes corresponded in relative mobility and relative isoelectric point among inbred strains to that recently reported for esterase-22 by Eisenhardt and von Deimling [(1982). Comp. Biochem. Physiol. 73B:719]. This genetic evidence, plus a wide variety of comparative biochemical and physiological data, indicates that egasyn is identical to esterase-22. Both parental types of egasyn isozymes are expressed in heterozygous F₁ progeny, suggesting that alterations in the egasyn structural gene are responsible for the altered isoelectric points. Also, egasyn is a monomer since no new esterase bands appear in F₁ progeny. The variants in isoelectric point of egasyn map at or near the egasyn (Eg) gene within the esterases of cluster 1 near Es-9 on chromosome 8.This work was supported by Grant GM-33559 from the National Institutes of Health.     

Small for gestational age and the metabolic syndrome: which mechanism is suggested by epidemiological and clinical studies?

The metabolic and cardiovascular complications associated with in-utero undernutrition have been identified during the past 10 years. Reduced fetal growth is independently associated with an increased risk of development of cardiovascular diseases, the insulin-resistance syndrome or one of its components (i.e., hypertension, dyslipidaemia, impaired glucose tolerance and type 2 diabetes). Insulin resistance appears to be a key component underlying these metabolic complications. Although the mechanism remains unclear, several pieces of evidence support an active role of adipose tissue in the emergence of insulin resistance (an abnormal growth pattern and repartition, hypersensitivity to catecholamines, regulation of leptin and adiponectin secretion and modulation of peroxisome proliferator-activated receptor gamma). Among individuals born SGA, those who are more at risk of gaining excess adiposity are those who are thin at birth following a period of fetal growth restriction. This period of undernutrition is followed by a neonatal period of catch-up growth and renutrition. This pattern induces important modifications in adipose tissue, with long-term consequences, among which is a high risk of early development of insulin resistance. Not all individuals born SGA will show such modifications in adipose tissue, meaning that not all of those born SGA are at risk of insulin resistance and diabetes. From a broader point of view, several hypotheses have been proposed over the past 10 years to explain this unexpected association between being born SGA and the later development of disease. Each of them points to a detrimental fetal environment, to a genetic susceptibility or to interactions between these two components playing a critical role in this context. Although not confirmed, the hypothesis suggesting that this association could be the consequence of genetic/environmental interactions remains the most attractive.     

Cancer therapy at the crossroads: which direction for the future?

Magnetic resonance spectroscopy has revealed that cell death in tumors undergoing therapy may follow either from auto-oxidative cellular injury (ACI) or from programmed cell death (apoptosis), depending on the particular form of treatment employed and on its intensity. This short review argues not only in favor of ACI as the preferred mode of cell death, but also for a better understanding of the relationship between the nature of the changes stressed cells undergo and patterns of drug resistance accompanying survival if therapy is to become more successful.     

Interpreting biological degradative processes acting on mammalian hair in the living and the dead: which ones are taphonomic?

Although the taphonomic (post-mortem) degradation processes relevant to teeth and bones have been well described, those taking place with regards to mammalian hairs have not been characterized to the same extent. This present article describes, in detail, microscopic changes resulting from the actions of biological agents that digest and degrade hairs. The most noteworthy and prevalent agents responsible for the destruction of hair structure are fungi, which use a range of strategies to invade and digest hairs. One of the most important finds to emerge from this study is that taphonomic structures and processes can easily be interpreted by the unwary as ‘real’, or as class characteristics for a particular animal taxon. Moreover, under certain conditions, ‘taphonomic’ processes normally associated with the dead are also present on the hairs of the living. This work will improve the reliability of hair examinations in forensic, archaeological and palaeontological applications—in addition, the finding has relevance in the protection of mammalian collections susceptible to infestation. This article also addresses the popular myth that ancient peoples were often red-haired and discusses phenomena responsible for this observation. Insights gained from detailed characterization of taphonomic processes in 95 hairs from a variety of species demonstrate the range and breadth of degradative effects on hair structure and colour. Lastly, the study demonstrates that hairs often tell a story and that there is value of extracting as much morphological data as possible from hairs, prior to destructive sampling for biomolecules.     

Synthesis and biological evaluation of a peptide-paclitaxel conjugate which targets the integrin αvβ₆

The integrin α(v)β(6) is an emergent biomarker for non-small cell lung cancer (NSCLC) as well as other carcinomas. We previously developed a tetrameric peptide, referred to as H2009.1, which binds α(v)β(6) and displays minimal affinity for other RGD-binding integrins. Here we report the use of this peptide to actively deliver paclitaxel to α(v)β(6)-positive cells. We synthesized a water soluble paclitaxel-H2009.1 peptide conjugate in which the 2'-position of paclitaxel is attached to the tetrameric peptide via an ester linkage. The conjugate maintains its specificity for α(v)β(6)-expressing NSCLC cells, resulting in selective cytotoxicity. Treatment of α(v)β(6)-positive cells with the conjugate results in cell cycle arrest followed by induction of apoptosis in the same manner as free paclitaxel. However, initiation of apoptosis and the resultant cell death is delayed compared to free drug. The conjugate demonstrates anti-tumor activity in a H2009 xenograft model of NSCLC with efficacy comparable to treatment with free paclitaxel.     

Mimicry vs. similarity: which resemblances between brood parasites and their hosts are mimetic and which are not?

Mimicry is one of the most conspicuous and puzzling phenomena in nature. The best-known examples come from insects and brood parasitic birds. Unfortunately, the term 'mimicry' is used indiscriminately and inconsistently in the brood parasitic literature despite the obvious fact that similarities of eggs, nestlings and adults of brood parasites to their hosts could result from many different processes (phylogenetic constraint, predation, intraspecific arms-races, vocal imitation, exploitation of pre-existing preferences, etc.). In this note I wish to plead for a more careful use of the term. I review various processes leading to a similarity between propagules (both eggs and nestlings) of brood parasites and their hosts and stress that: (1) mimetic and non-mimetic similarities should be differentiated, (2) a mere similarity of host and parasite propagules provides no evidence for mimicry, (3) mimicry is more usefully understood as a (coevolutionary) process rather than an appearance, and (4) mimicry terminology should reflect the process which led to mimetic similarity. Accepting the mimicry hypothesis requires both the experimental approach and rejection of alternative hypotheses explaining similarities of host and parasite propagules.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 69–78.     

Cell-death alternative model organisms: why and which?

Classical model organisms have helped greatly in our understanding of cell death but, at the same time, might have constrained it. The use of other, non-classical model organisms from all biological kingdoms could reveal undetected molecular pathways and better-defined morphological types of cell death. Here we discuss what is known and what might be learned from these alternative model systems.     

Puncture versus capture: which stresses animals the most?

Journal of Comparative Physiology B - The prerogative of animal welfare science includes wild species and ecological studies. Yet, guidance enshrined in legislation is narrowly derived from studies...