Are chemical barriers necessary for evolution of butterfly-plant associations?

Summary The association between heliconiine butterflies and Passion flower vines is composed of three or more subassociations, in which each Heliconius species group feeds on a different Passiflora subgenus. The relationships are consistent with the adaptive zone hypothesis of Ehrlich and Raven, which would suggest that (1) species of the subgenus Plectostemma proliferated as a result of chemical barriers to herbivory, which created a herbivore-free adaptive zone in which speciation and diversification took place, and (2) species of the H. erato-charitonia group overcame these barriers and entered a competitor-free adaptive zone, in which they proliferated and speciated with those plants as hosts. The hypothesis that plant secondary chemicals were responsible for creating such barriers to herbivory was tested using heliconiine species as bioassays, in which reduced growth rates indicated presence of chemical barriers to feeding. Contrary to expectation, plants of the subgenus Plectostemma showed little or no chemical defense against any species of heliconiine caterpillar. In contrast many plants of the primitive subgenus Granadilla possessed significant chemical barriers against herbivory by heliconiine larvae, excepting those species in the H. numata-melpomene species group. I concluded that chemical barriers to feeding were not responsible for proliferation and diversification in the subgenus Plectostemma, nor did chemicals create a competitor-free adaptive zone in which the H. erato-charitonia species-group could proliferate and speciate. Chemical barriers may have been important in the evolution of the subgenus Granadilla-heliconiine association. I suggest that plant allelochemics are only one of many possible barriers to herbivory which can help create adaptive zones for plants and their herbivores, and that the patterns of butterfly foodplant specialization discussed by Ehrlich and Raven (1964) are not necessarily the result of biochemical adaptation and counteradaptation.     

Is photobleaching necessary for Raman imaging of bone tissue using a green laser?

Raman microspectroscopy is widely used for musculoskeletal tissues studies. But the fluorescence background obscures prominent Raman bands of mineral and matrix components of bone tissue. A 532-nm laser irradiation has been used efficiently to remove the fluorescence background from Raman spectra of cortical bone. Photochemical bleaching reduces over 80% of the fluorescence background after 2 h and is found to be nondestructive within 40 min. The use of electron multiplying couple charge detector (EMCCD) enables to acquire Raman spectra of bone tissues within 1-5 s range and to obtain Raman images less than in 10 min.     

Is photobleaching necessary for Raman imaging of bone tissue using a green laser?

Raman microspectroscopy is widely used for musculoskeletal tissues studies. But the fluorescence background obscures prominent Raman bands of mineral and matrix components of bone tissue. A 532-nm laser irradiation has been used efficiently to remove the fluorescence background from Raman spectra of cortical bone. Photochemical bleaching reduces over 80% of the fluorescence background after 2 h and is found to be nondestructive within 40 min. The use of electron multiplying couple charge detector (EMCCD) enables to acquire Raman spectra of bone tissues within 1-5 s range and to obtain Raman images less than in 10 min.     

Is a decrease in cyclic AMP a necessary and sufficient signal for maturation of amphibian oocytes?

Acetylcholine rapidly lowered the intracellular levels of cyclic AMP in stage 5 and 6 Xenopus laevis oocytes. Acetylcholine alone did not induce oocyte maturation, though it did accelerate maturation induced by progesterone. The effect of acetylcholine on oocyte maturation was independent of extracellular calcium concentration. Adenosine increased cyclic AMP and abolished the progesterone-induced decrease in cyclic AMP levels in follicles and in denuded oocytes. This effect of adenosine was blocked by the Ra purinergic receptor antagonist, theophylline. Despite those effects, adenosine alone induced maturation in stage 6 oocytes and accelerated progesterone-induced maturation in both stage 5 and 6 cells. Adenosine also induced a significant increase in the rate of 45Ca efflux from oocytes in the presence and the absence of external calcium. We suggest that the activation of cell surface receptors involved in the release of calcium from cellular stores may induce or accelerate oocyte maturation independently of small changes in intracellular cyclic AMP concentration.     

Is it necessary for screening irregular antibodies of blood donors?

To explore the necessity of electronic crossmatching applied to irregular antibodies from blood donors, to ensure blood transfusion safety. Irregular antibody screening was performed on blood samples collected in the Dongguan Blood Center from Apr 17, 2014 to Dec 31, 2017. Primary screening was performed on the Sanquin automatic blood group analyzer by the microcolumn gel method (Sanquin). The positive samples were analyzed again using the salt medium method, polybrene method and micro-column gel method (Diana) for the second screening. If the second screening was positive, it was used to determine irregular antibody specificity (using panel cells) and any irregular antibody titer was detected. A total of 208,004 samples were detected, of which 316 were positive (316/208,004; 0.152%). Among them, 120 alloantibodies (120/135,139; 0.088%) were detected in male donors, which was much lower than in female donors (173/72,865; 0.237%) (P<0.01). A total of 16 kinds of known irregular antibodies and 40 cases of unknown antibody specificity were detected, with 119 cases of IgG type and 197 cases of IgM type, at the ratio of 1.65:1. In female donors, the frequencies of anti-D, anti-E, anti-M and anti-Le^a were significantly higher than in male donors (P<0.01). In married couples, the frequencies of anti-D and anti-E were significantly higher than those unmarried (P<0.05). In minority nationalities, the frequency of anti-M was significantly higher than in the Han nationality (P<0.05). In non-Guangdong donors, the frequencies of anti-D and anti-Le^a were significantly higher than in Guangdong donors. 87.02% of irregular antibody positive donors’ antibody titers were lower than “++”, which was deemed as no serious hazard for clinical transfusion. The study suggests that it is unnecessary to screen for irregular antibodies in blood donors. Male donors from Guangdong may not be required to undergo screening for irregular antibodies, and anti-D and anti-E only identification is also not required to be detected in female donors.     

Is it necessary for screening irregular antibodies of blood donors?

To explore the necessity of electronic crossmatching applied to irregular antibodies from blood donors, to ensure blood transfusion safety. Irregular antibody screening was performed on blood samples collected in the Dongguan Blood Center from Apr 17, 2014 to Dec 31, 2017. Primary screening was performed on the Sanquin automatic blood group analyzer by the microcolumn gel method (Sanquin). The positive samples were analyzed again using the salt medium method, polybrene method and micro-column gel method (Diana) for the second screening. If the second screening was positive, it was used to determine irregular antibody specificity (using panel cells) and any irregular antibody titer was detected. A total of 208,004 samples were detected, of which 316 were positive (316/208,004; 0.152%). Among them, 120 alloantibodies (120/135,139; 0.088%) were detected in male donors, which was much lower than in female donors (173/72,865; 0.237%) (P<0.01). A total of 16 kinds of known irregular antibodies and 40 cases of unknown antibody specificity were detected, with 119 cases of IgG type and 197 cases of IgM type, at the ratio of 1.65:1. In female donors, the frequencies of anti-D, anti-E, anti-M and anti-Le^a were significantly higher than in male donors (P<0.01). In married couples, the frequencies of anti-D and anti-E were significantly higher than those unmarried (P<0.05). In minority nationalities, the frequency of anti-M was significantly higher than in the Han nationality (P<0.05). In non-Guangdong donors, the frequencies of anti-D and anti-Le^a were significantly higher than in Guangdong donors. 87.02% of irregular antibody positive donors’ antibody titers were lower than “++”, which was deemed as no serious hazard for clinical transfusion. The study suggests that it is unnecessary to screen for irregular antibodies in blood donors. Male donors from Guangdong may not be required to undergo screening for irregular antibodies, and anti-D and anti-E only identification is also not required to be detected in female donors.     

Is the nexus necessary for cell-to-cell coupling of smooth muscle?

Summary Electronmicroscopic study of electrically coupled smooth muscles was undertaken to determine the distribution of nexuses in various types of smooth muscle. The study revealed that while nexal structures were commonplace in some types of smooth muscle, they were very rare or absent in others, even though in some cases these cells were only a few nanometers distant from one another. The persistence in thin section of these structures in the main circular muscle of dog intestine after poor fixation, fixation under strain, cell shrinkage, and metabolic damage of various sorts seems to rule out the thesis that they are labile. The absence of nexuses in longitudinal muscle of dog intestine examined both by thin section and by freeze fracture suggests that in this tissue they are absent or very rarein vivo and cannot account for electrical coupling.Nexuses were discernible in thin sections of main circular muscle after a variety of experimental conditions of fixation. Metabolic inhibition orin vitro permanganate fixation partially destroyed nexal contacts. These procedures induced tissue, membrane apposition and an accompanying increase in the number of structures which resemble nexuses at low magnification (nexus-like structures). Nexus-like structures occurred in all smooth muscle fixed byin vitro permanganate associated with apposition of membranes and poor preservation of basement membrane. A technique ofin vitro permanganate fixation was developed which prevented tissue swelling; consequently nexus-like structures were absent in tissues so treated. The suggestion is made that some structures described in the literature as nexuses, following permanganate fixation, may represent nexus-like structures.The balance of evidence suggests that nexuses need not be present for electrical coupling of some smooth muscle cells, in which other types of cell-to-cell contacts must be invoked.     

Is a decline in offspring quality a necessary consequence of maternal age?

Recent studies in two species of Drosophila have demonstrated a negative effect of parental age on offspring fitness, including a reduced hatch rate of eggs and larval-to-adult viability. This has led to a call to consider the decline of offspring quality as a function of parental age in theoretical considerations of the evolution of ageing. We have tested whether a decline in egg and larval quality of older mothers is a general feature of senescence by examining it in the cockroach Nauphoeta cinerea. We also tested whether maternal age affected the reproductive potential of daughters. Although maternal age at first reproduction profoundly affected maternal fitness, there was no difference in hatch rate or larval viability between the offspring of young and old mothers. Likewise, the reproductive potential of the daughters of young and old mothers was the same. Thus, while maternal age effects may be important aspects of ageing in some systems, the generality and overall importance for theories of ageing remain unclear.     

Human grief: Is its intensity related to the reproductive value of the deceased?

Thurstone's method of comparative judgement was used to measured the intensity of grief that parents of high-, moderate-, and low-reproductive value were expected to experience at the death of male and female children of different ages. The results were correlated with reproductive values for male and female British Columbians and for !Kung Bushwomen. Grief ratings were more highly correlated with reproductive value than with age and more highly correlated with reproductive values of !King Bushwomen than with those of British Columbians. The correlations were higher for male- than for female-stimulus children. The correlations of female ratings with reproductive value were higher than male ratings with reproductive value, although not as high as expected. However, the correlation between grief ratings and reproductive value did not increase as the reproductive value of the raters declined.     

Parasites lost? An overlooked hypothesis for the evolution of alternative reproductive strategies in amphibians

Amphibians exhibit the greatest diversity of reproductive strategies of all tetrapod vertebrates. While authors have traditionally attributed the evolution of these strategies to factors such as complex topography, unpredictable larval environments, and predation on larvae and eggs, support for any of these hypotheses has been limited. Importantly, most authors have ignored parasites, including unicellular pathogens and multicellular parasites, as selective agents capable of influencing amphibian evolution. Insights in disease transmission, amphibian immunity, and their interaction with various life histories require that we consider parasites to be selective pressures in our exploration of the evolution of amphibian reproductive strategies. I review recent findings and describe how these principles converge to form a novel conceptual hypothesis for the evolution of alternative reproductive strategies in amphibians. I offer some specific predictions and recommend that parasites be considered with other selective pressures when constructing formal, falsifiable hypotheses during evaluative studies of amphibian reproductive behavior.     

Is a rise in intracellular concentration of free calcium necessary or sufficient for stimulated cytoskeletal-associated actin?

The addition of the calcium ionophore A23187 to rabbit neutrophils increases the amount of actin associated with the cytoskeleton regardless of the presence or absence of calcium in the incubation medium. In the presence of extracellular calcium, the effect of A23187 is biphasic with respect to concentration. The action of the ionophore is rapid, transient, and is inhibited by pertussis toxin, hyperosmolarity, and quinacrine. On the other hand, the addition of pertussis toxin or hyperosmolarity has small if any, effect on the rise in intracellular calcium produced by A23187. While quinacrine does not affect the fMet-Leu-Phe-induced increase in cytoskeletal actin and the polyphosphoinositide turnover, its addition inhibits completely the stimulated increase in Ca-influx produced by the same stimulus. The results presented here suggest that a rise in the intracellular concentration of free calcium is neither necessary nor sufficient for the stimulated increase in cytoskeletal-associated actin. A possible relationship between the lipid remodeling stimulated by chemoattractants and the increased cytoskeletal actin is discussed.     

Cognitive effects of variations in pubertal timing: Is puberty a period of brain organization for human sex-typed cognition?

There is considerable interest in the organizational effects of pubertal sex hormones on human sex-related characteristics. Recent evidence from rodents suggests that there is a decreasing window of sensitivity to sex hormones throughout adolescence. If adolescence also represents a period of brain organization in human beings, then the timing of exposure to sex-typical hormones at puberty should have long-term effects on sex-typed characteristics: individuals with early timing should be more sex-typed than individuals with late timing. We tested this hypothesis in 320 young adults by relating their pubertal timing (retrospective comparison to peers) to cognitive abilities that show sex differences. Results provide partial support for the hypothesis. For men, pubertal timing was inversely related to scores on a test of three-dimensional mental rotations. Effects do not appear to be due to duration of hormone exposure (time since puberty), but other potential influences need further study.     

New records of an invasive bumble bee in northern Chile: expansion of its range or new introduction events?

The Eurasian bumble bee Bombus terrestris Linnaeus has been used commercially for pollination of a large number of crop species worldwide. This species has become invasive in several countries where it has escaped into natural environments. This species has become naturalized in many zones of Chile and southern Argentina, and may potentially invade other regions and countries in South America. These naturalized populations of B. terrestris have been associated with rapid population declines of the native bee B. dahlbomii Guérin-Méneville. We report new records of the exotic bee B. terrestris in the Region de Arica y Parinacota in the far north of Chile, which includes portions of the Atacama Desert. We used species distribution models (SDMs) and multivariate analyses to evaluate whether these occurrences represent new escapes from managed colonies or natural dispersal of the species from its southern invaded range. These reports of B. terrestris indicate a northward expansion of this bee. In our analyses, these new areas of occurrences have environmental conditions similar to those observed in the species’ southern invaded range, and our SDMs predict that B. terrestris dispersal through the Atacama is possible, although not likely given the occasional flower blooming in that region of Chile. These new occurrences in northern Chile reflect a potential for future invasion into other regions of South America by B. terrestris. Future surveys in the area should be intensified to evaluate if viable populations of this invasive species may become established.     

Is the computed speciation of copper in a wide range of Chinese soils reliable?

Free Cu species in soils is a key issue to its bioavailability. However, predictive models for Cu speciation across a wide range of soils were still unavailable. In this study, Cu speciation in 34 contaminated soil samples were investigated via analytical technique and predictive models. The results showed that most of free Cu²⁺ was underestimated when using default log K_CuFA and 65% active fulvic acid as inputs in models of WHAM VI and NICA-Donnan. The best prediction was found when using either adjusted active fulvic acid from 10% to 125% for WHAM VI or from 15% to 65% for NICA-Donnan model with the RMSE < 0.32 and r² > 0.96. In contrast, NICA-Donnan demonstrated a slightly stronger binding for Cu than WHAM VI due to extra 26% of samples was underestimated. This work presents a comprehensive database of Cu speciation and an effective attempt of free Cu²⁺ prediction in a wide range of Chinese soils.     

The evolution of comparative cognition: Is the snark still a boojum?

In “The Snark is a Boojum”, Beach [Beach, F.A., 1950. The snark was a boojum. American Psychologist. 5, 115–124] famously asserted that animal psychology embraced too few species and too few problems to deserve the name comparative. Later in the 20th century, others [e.g. Kamil, A.C., 1988. A synthetic approach to the study of animal intelligence. In: Leger, D.W. (Ed.), Comparative Perspectives in Modern Psychology. Nebraska Symposium on Motivation, vol. 35. University of Nebraska Press, Lincoln, NE, pp. 230–257; Shettleworth, S.J., 1993. Where is the comparison in comparative cognition? Alternative research programs. Psychological Science. 4, 179–184] expressed similar concerns about the new subfield of comparative cognition, suggesting that a more biological approach to choice of species and problems was needed to balance a dominant anthropocentrism. The last 10–15 years have seen many new developments, and a recent survey like Beach’s reveals a very different picture. Not only are many more species being studied, contributions by researchers from different backgrounds are increasing, and research on comparative cognition is better connected with developmental psychology, behavioral neuroscience, primatology, behavioral ecology, and other fields. Contemporary research addresses three major aspects of cognition about equally: basic processes, physical cognition, and social cognition. This article describes a selected research program from each area, chosen to exemplify current trends and challenges for the field.