Countershading enhances crypsis with some bird species but not others

Although the theory of self-shadow concealing countershadingis over a century old, there are very few direct empirical teststo substantiate the prediction that prey that are dorsally darkenedand ventrally lightened (generally termed countershaded) sufferlower rates of attack than other prey. In this paper, we reportexperiments designed to determine whether artificial, countershadedprey are chosen by predators less often than those that areall light, all dark, or reverse shaded (i.e., dorsally lightenedand ventrally darkened). Artificial prey were presented in gardensand parks to free-living birds, either on white backgroundsor on backgrounds with some degrees of color matching. In oneexperiment, birds were unmarked, and in the other, they wereindividually identifiable. We found that in three experimentaltrials, countershaded baits were attacked at a rate not significantlydifferent from that of uniformly dark baits. In one experimentaltrial, countershaded baits were at some advantage. When we examinedthe data set for this trial more closely, it was apparent thatblackbirds were taking countershaded baits least often, butblue tits and robins conferred no special advantage to countershadedbaits. Hence, the efficacy of countershading may vary with speciesof predator.     

A sparse neural code for some speech sounds but not for others

The precise neural mechanisms underlying speech sound representations are still a matter of debate. Proponents of 'sparse representations' assume that on the level of speech sounds, only contrastive or otherwise not predictable information is stored in long-term memory. Here, in a passive oddball paradigm, we challenge the neural foundations of such a 'sparse' representation; we use words that differ only in their penultimate consonant ("coronal" [t] vs. "dorsal" [k] place of articulation) and for example distinguish between the German nouns Latz ([lats]; bib) and Lachs ([laks]; salmon). Changes from standard [t] to deviant [k] and vice versa elicited a discernible Mismatch Negativity (MMN) response. Crucially, however, the MMN for the deviant [lats] was stronger than the MMN for the deviant [laks]. Source localization showed this difference to be due to enhanced brain activity in right superior temporal cortex. These findings reflect a difference in phonological 'sparsity': Coronal [t] segments, but not dorsal [k] segments, are based on more sparse representations and elicit less specific neural predictions; sensory deviations from this prediction are more readily 'tolerated' and accordingly trigger weaker MMNs. The results foster the neurocomputational reality of 'representationally sparse' models of speech perception that are compatible with more general predictive mechanisms in auditory perception.     

Dissecting why superovulation and embryo transfer usually work on some farms but not on others

Bovine embryo transfer is a well-established commercial industry that is often associated with veterinary practices. Practitioners offering embryo transfer services may possess a very high standard of technical expertise; however, success in the production of embryos and the impregnation of recipients cannot be achieved unless the cattle are healthy and maintained in a well-managed cattle operation. In addition to appropriate gonadotropin treatments of donor cattle, the use of highly fertile semen, known to have been properly stored and handled is required for success. Recipient cattle must be managed with the same attention to detail as donors. Traditionally, PGF has been used for the synchronization of recipients. However, PGF is limited in its effectiveness early and late in the bovine estrus cycle. Recipient estrus synchronization with progesterone releasing intravaginal inserts has been successful and high pregnancy rates have resulted following embryo transfer.     

PMA alone induces proliferation of some murine T cell clones but not others

The responses of cloned murine T cell lines to the phorbol ester, phorbol myristate acetate (PMA), were investigated. PMA alone was able to stimulate proliferation of some clones but not others. Two Lyt-2+, cloned cytolytic T lymphocyte (CTL) lines proliferated in response to stimulation by PMA alone, but several L3T4+, cloned helper T lymphocyte (HTL) lines did not. In contrast, all clones tested released lymphokines in response to stimulation by the combination of PMA and the calcium ionophore A23187. Moreover, all clones proliferated in response to stimulation by the combination of PMA and A23187. The proliferation of HTL in response to PMA + A23187 could be completely inhibited either by cyclosporine A (CsA) or by PC61.5, a monoclonal antibody directed against the murine IL 2 receptor; however, the proliferation of CTL in response to PMA alone was not affected either by CsA or by PC61.5. These results suggest that of the murine T cell clones tested, HTL proliferate in response to stimulation via an IL 2-dependent, autocrine pathway; in contrast, CTL, in addition to an IL 2-dependent pathway, may possess an additional IL 2-independent pathway of proliferation. CTL that proliferate in response to stimulation by PMA alone may be useful models in the study of T cell proliferation.     

Liposomal amphotericin B is toxic to fungal cells but not to mammalian cells

Amphotericin B is an efficacious but extremely toxic anti fungal drug. Recently it has been shown that the incorporation of Amphotericin B in multilamellar liposomes results in a marked reduction in drug toxicity in mice with no loss of anti fungal potency. Until now, the mechanistic basis of the enhanced therapeutic index of liposomal Amphotericin B has been unclear. In this report, however, we show that the in vivo effects can be mimicked in vitro where free but not liposomal Amphotericin B causes lysis of erythrocytes while both free and liposomal drug kill fungal cells. These results suggest that the markedly improved therapeutic index of liposomal Amphotericin B is largely due to a fundamental alteration in the ability of the drug to interact with mammalian cell membranes rather than to alterations in pharmacokinetics or drug distribution.     

Epidermal growth factor advances some aspects of development but retards others in both rats and hamsters

The present experiments were undertaken to confirm the recent suggestion that epidermal growth factor (EGF) can have both retarding and accelerating effects on development, using a greater number of developmental indices than hitherto; to extend such studies to another species, the golden hamster, and to compare the responses of males and females. On each of days 0-3, one male and one female rat pup from each of 16 litters of 6 pups were injected subcutaneously with human EGF (0.5 micrograms/g body weight), one male and one female with vehicle, and the remaining two pups were not injected. As expected, EGF accelerated incisor eruption and eye-opening. However, EGF retarded the detachment of the pinna and the appearance of the auditory startle response. Free-fall righting was little affected. Hamster litters were left undisturbed till day 7 to minimise infanticide. Thereafter, experimental design was as far as possible the same as for the rats. Pups from 18 litters were injected on days 7-10. EGF advanced eye-opening, but retarded auditory startling, vaginal opening and the weaning growth spurt. Free-fall righting was unaffected. Hence, EGF had similar accelerating and retarding effects on development in both rats and hamsters. Also, these effects were the same in males and females for most indices.     

Surface ciliation of anuran amphibian larvae: persistence to late stages in some species but not others

Scanning electron microscopy was used to examine the surfaces of 21 species of tadpoles from six families, from Gosner Stage 25/26 until close to metamorphosis. Contrary to most previous reports, ciliated epidermal cells persisted until late stages in many but not all species and not at all locations examined. The commonest location for ciliated cells was around the nostrils, suggesting a role in chemosensation. Ciliated cells also occurred around the circumference of the eye, suggesting a cleaning role. Several species had ciliated cells on the tail. The densest, most regular arrays of ciliated cells occurred in species that tend to hang motionless in still-water pools, suggesting a respiratory function for these cells.     

Homologous recombination is elevated in some Werner-like syndromes but not during normal in vitro or in vivo senescence of mammalian cells

Werner syndrome (WS) is a recessive genetic condition associated with markedly reduced replicative lifespans of cells in culture, high chromosomal instability in vivo and in vitro, and premature appearance of many characteristics of normal aging, including an increased incidence of cancer. We have monitored plasmid homologous recombination frequencies in diploid fibroblasts from 6 Werner or Werner-like syndrome patients, following transfection with a plasmid substrate containing 2 overlapping fragments of the TN5 Neor gene. Plasmid DNA recovered from these cells was then assayed for homologous recombination by (a) transformation of recA- bacteria to Ampr (indicating total viable plasmid) or Neor (indicating viable recombinant plasmid), and (b) by limited-cycle polymerase chain reaction (PCR) to co-amplify a recombinant fragment containing the overlap region, and a control region of the same plasmid, without bacterial transformation. Bacterial assay data indicated that recombination rates in 3 of the 6 WS strains were significantly elevated above normal controls; 4 of 6 appeared elevated by PCR assay. The highest-recombination WS strain showed evidence of reduced degradation of transfected plasmid DNA. For this small sample of WS strains, clinical severity of WS was not well correlated with recombination rate as determined by either assay (Pearson r = 0.78, not significant, for PCR assay); elevated recombination may, however, define a subset of WS at greatest risk for cancer and/or atherosclerosis. PCR assay of a hyperoxia-resistant HeLa cell line, displaying substantially increased chromosome breakage, indicated increased recombination between direct-repeat fragments. Nevertheless, elevated recombination in WS strains is unlikely to be secondary to impaired replicative capacity characteristic of WS cells, or to defective repair of chromosome damage which is increased in WS, since recombination in non-WS strains was unaffected by passage level or repeated UV irradiation.     

Expression of the ASV src gene in hybrids between normal and virally transformed cells: Specific suppression occurs in some hybrids but not others

Somatic cell hybrids have been made between clones of rat cells transformed by avian sarcoma virus and rat or mouse cells that are untransformed. Intraspecies hybrids were either predominantly morphologically normal or predominantly transformed, some clones that formed transformed intraspecies hybrids yielding normal interspecies hybrids. Untransformed hybrids usually showed no detectable alteration in the structure or location of the integrated provirus, but viral RNA and pp60^src kinase activities were much reduced. No decrease in viral gene expression was seen in transformed hybrids. Thus hybrid suppression of viral transformation, mediated in trans by the untransformed parent, is a specific event that depends on both untransformed and transformed parental parameters.     

Group I but not Group II NPV induces antiviral effects in mammalian cells

Nucleopolyhedrovirus(NPV) is divided into Group I and Group II based on the phy-logenetic analysis.It has been reported that Group I NPVs such as Autographa californica multiple NPV(AcMNPV) can transduce mammalian cells,while Group II NPVs such as Helicoverpa armigera single NPV(HaSNPV) cannot.Here we report that AcMNPV was capable of stimulating antiviral ac-tivity in human hepatoma cells(SMMC-7721) manifested by inhibition of Vesicular Stomatitis virus(VSV) replication.In contrast,the HaSNPV and the Spodoptera exigua multiple NPV(SeMNPV) of group II had no inhibitory effect on VSV.Recombinant AcMNPV was shown to induce interferons al-pha/beta even in the absence of transgene expression in human SMMC-7721 cells,while it mediated transgene expression in BHK and L929 mammalian cells without an ensuing antiviral activity.     

Group I but not Group II NPV induces antiviral effects in mammalian cells

Nucleopolyhedrovirus (NPV) is divided into Group I and Group II based on the phylogenetic analysis. It has been reported that Group I NPVs such as Autographa californica multiple NPV (AcMNPV) can transduce mammalian cells, while Group II NPVs such as Helicoverpa armigera single NPV (HaSNPV) cannot. Here we report that AcMNPV was capable of stimulating antiviral activity in human hepatoma cells (SMMC-7721) manifested by inhibition of Vesicular Stomatitis virus (VSV) replication. In contrast, the HaSNPV and the Spodoptera exigua multiple NPV (SeMNPV) of group II had no inhibitory effect on VSV. Recombinant AcMNPV was shown to induce interferons alpha/beta even in the absence of transgene expression in human SMMC-7721 cells, while it mediated transgene expression in BHK and L929 mammalian cells without an ensuing antiviral activity.     

Group Ⅰ but not Group Ⅱ NPV induces antiviral effects in mammalian cells

Nucleopolyhedrovirus (NPV) is divided into Group Ⅰ and Group Ⅱ based on the phylogenetic analysis. It has been reported that Group Ⅰ NPVs such as Autographa californica multiple NPV (AcMNPV) can transduce mammalian cells, while Group Ⅱ NPVs such as Helicoverpa armigera single NPV (HaSNPV) cannot. Here we report that AcMNPV was capable of stimulating antiviral activity in human hepatoma cells (SMMC-7721) manifested by inhibition of Vesicular Stomatitis virus (VSV) replication. In contrast, the HaSNPV and the Spodoptera exigua multiple NPV (SeMNPV) of group Ⅱ had no inhibitory effect on VSV. Recombinant AcMNPV was shown to induce interferons alpha/beta even in the absence of transgene expression in human SMMC-7721 cells, while it mediated transgene expression in BHK and L929 mammalian cells without an ensuing antiviral activity.     

Increased temperature disrupts chemical communication in some species but not others: The importance of local adaptation and distribution

Environmental conditions experienced by a species during its evolutionary history may shape the signals it uses for communication. Consequently, rapid environmental changes may lead to less effective signals, which interfere with communication between individuals, altering life history traits such as predator detection and mate searching. Increased temperature can reduce the efficacy of scent marks released by male lizards, but the extent to which this negative effect is related to specific biological traits and evolutionary histories across species and populations have not been explored. We experimentally tested how increased temperature affects the efficacy of chemical signals of high‐ and low‐altitude populations of three lizard species that differ in their ecological requirements and altitudinal distributions. We tested the behavioral chemosensory responses of males from each species and population to male scent marks that had been incubated at one of two temperatures (cold 16°C or hot 20°C). In high‐altitude populations of a mountain species (Iberolacerta monticola), the efficacy of chemical signals (i.e., latency time and number of tongue flicks) was lower after scent marks had been exposed to a hot temperature. The temperature that scent marks were incubated at did not affect the efficacy of chemical signals in a ubiquitous species (Podarcis muralis) or another mountain species (I. bonalli). Our results suggest that specific ecological traits arising through local adaptation to restricted distributions may be important in determining species vulnerability to climatic change.     

Behaviour in captivity predicts some aspects of natural behaviour,but not others,in a wild cricket population

Examining the relevance of ‘animal personality’ involves linking consistent among- and within-individual behavioural variation to fitness in the wild. Studies aiming to do this typically assay personality in captivity and rely on the assumption that measures of traits in the laboratory reflect their expression in nature. We examined this rarely tested assumption by comparing laboratory and field measurements of the behaviour of wild field crickets (Gryllus campestris) by continuously monitoring individual behaviour in nature, and repeatedly capturing the same individuals and measuring their behaviour in captivity. We focused on three traits that are frequently examined in personality studies: shyness, activity and exploration. All of them showed repeatability in the laboratory. Laboratory activity and exploration predicted the expression of their equivalent behaviours in the wild, but shyness did not. Traits in the wild were predictably influenced by environmental factors such as temperature and sunlight, but only activity showed appreciable within-individual repeatability. This suggests that some behaviours typically studied as personality traits can be accurately assayed in captivity, but the expression of others may be highly context-specific. Our results highlight the importance of validating the relevance of laboratory behavioural assays to analogous traits measured in the wild.     

Substrate flexibility regulates growth and apoptosis of normal but not transformed cells

One of the hallmarks of oncogenictransformation is anchorage-independent growth (27). Herewe demonstrate that responses to substrate rigidity play a major rolein distinguishing the growth behavior of normal cells from that oftransformed cells. We cultured normal or H-ras-transformedNIH 3T3 cells on flexible collagen-coated polyacrylamide substrateswith similar chemical properties but different rigidity. Compared withcells cultured on stiff substrates, nontransformed cells on flexiblesubstrates showed a decrease in the rate of DNA synthesis and anincrease in the rate of apoptosis. These responses on flexiblesubstrates are coupled to decreases in cell spreading area and tractionforces. In contrast, transformed cells maintained their growth andapoptotic characteristics regardless of substrate flexibility. Theresponses in cell spreading area and traction forces to substrateflexibility were similarly diminished. Our results suggest that normalcells are capable of probing substrate rigidity and that propermechanical feedback is required for regulating cell shape, cell growth,and survival. The loss of this response can explain the unregulated growth of transformed cells.