The failure of morphology to contribute to the modern synthesis

How much, if anything, morphology contributed to the modern synthesis is partly a matter of how one defines that term. In the strict sense, morphology is a purely formal discipline and had very little to contribute. Morphology may also be considered a kind of data, and when it becomes functional a better case can be made for its role in evolutionary studies. Be that as it may, the incorporation of morphology into the synthesis was a later development. The initial focus was at the populational level, including the problems of speciation, which makes sense because that was where the opportunities seemed to be. As the synthesis evolved and matured it expanded its horizons and incorporated a larger range of topics. Very little discussion of morphology occurs in the canonical writings of the so-called architects. At the time when the synthesis was supposedly complete, which was around 1950, the incorporation of morphology into it was just beginning.     

My perpetual cycle: from student to researcher to teacher to student ..

This contribution stems from the personal experience of the author regarding how he became acquainted with embryology and how he finally entered the field of developmental biology. It reports his feelings as a student of the Histology and Embryology course as it was taught in the late 1970s, and his present efforts in teaching developmental biology to university students. In the Developmental Biology course at Pisa University today, students are taught the tissue, molecular and genetic mechanisms that regulate development of several model systems. Drosophila is introduced at the beginning, because of the great knowledge that it has brought to the unraveling of the molecular aspects of development and because it allows several basic concepts to be introduced, and vertebrate systems follow. Other topics include the classic experiments on amphibian systems, which are explained in the light of recent molecular advances, as well as the genetically more versatile vertebrate systems such as the mouse.     

In vivo phototransformation of phytochrome in relation to its binding to a particulate fraction of maize coleoptiles

When the phytochrome molecule of maize coleoptiles absorbs sufficientenergy it binds to its putative binding site in a particulatefraction irrespective of whether or not it is in the P_fr form.The extent of binding depends on the light dosage. Red lightis more efficient than far red light but both are effectivein causing phytochrome to bind. Using phytochrome binding tosubcellular particles as the prototype of a primary physiologicalresponse it is concluded that P_fr may not necessarily be theonly physiologically active form of phytochrome. (Received May 31, 1976; )     

Automated technique to evaluate thymocyte adhesion to thymic epithelial cells

Thymocyte adhesion to thymic epithelial cells is a relevant issue during intrathymic T-cell differentiation, and directly intervenes in the generation and expansion of the T-cell repertoire. In view of these data, it was apparent the usefulness of an automated strategy to evaluate the degree of thymic epithelial cell-thymocyte adhesion. This prompted us to develop an ELISA procedure (using an anti-Thy1 reagent) to determine the degree of thymocyte adhesion onto cultured thymic epithelial cells. The procedure described herein is simple, non-radioactive and reproducible. Additionally, it can potentially be applied to quantitate the degree of thymocyte adhesion to any cellular or non-cellular substrate (for example, extracellular matrix). Moreover, it detected fluctuations of thymocyte adhesion secondary to glucocorticoid treatment of epithelial cells. Thus, it can be regarded as a further tool to analyze intrathymic interactions.     

Attitude of zoo visitors to the idea of feeding live prey to zoo animals

Two hundred UK zoo visitors were asked about their attitudes regarding the feeding of live prey to zoo animals. All visitors agreed with live insects being fed to lizards, providing it was done off-exhibit, and only 4% objected if done on-exhibit. Seventy-two percent of visitors agreed with live fish being fed to penguins on-exhibit and 84.5% agreed to feeding live fish off-exhibit. However, only 32% agreed to a live rabbit being fed to a cheetah on exhibit, whereas 62.5% agreed to this if done off-exhibit. In general we found female interviewees more likely to object to the feeding of live vertebrate prey. Comments volunteered by interviewees suggested that they agreed with feeding live vertebrate prey because ‘it is natural’. If they objected, it was because ‘it would upset them or their children’. Zoo Biol 16:343–347, 1997. © 1997 Wiley-Liss, Inc.     

Institutional refusal to offer assisted dying: A response to Shadd and Shadd

Ever since medical assistance in dying (MAID) became legal in Canada in 2016, controversy has enveloped the refusal by many faith‐based institutions to allow this service on their premises. In a recent article in this journal, Philip and Joshua Shadd have proposed ‘changing the conversation’ on this issue, reframing it as an exercise not of conscience but of an institutional right of self‐governance. This reframing, they claim, will serve to show how health‐care institutions may be justified in refusing to provide MAID on moral or religious grounds. I argue that it will not make it easier to justify institutional refusal, and is likely to make it harder.     

Various sensitivities of yeasts to lycorine

Lycorine, an Amaryllidaceae alkaloid, is a powerful inhibitor of growth in higher plants and algae. Thirty-one strains of yeasts, belonging to different genera and species, were screened to study the effect of lycorine on their growth. The strains were incubated at 25 degrees C in a 2% glucose medium with different concentrations of lycorine (10, 50 and 100 microM), and their growth after 72 hours was evaluated. Most of the strains showed no sensitivity to lycorine. However, in Schizosaccharomyces pombe (IMAT-V Pbx) and Aureobasidium pullulans (DBV A77) lycorine significantly inhibited growth (59-73%), while, on the contrary, in Saccharomycopsis fibuligera (DBV 3812) and Cryptococcus terreus (CBS 1895) it was clearly stimulated (76-140%). The fact that lycorine inhibits growth in some yeasts while it stimulates it in others means that neither of the two previously formulated interpretations on the molecular mechanism of action of alkaloid can explain all cases. In other words, it does not seem that lycorine just inhibits protein synthesis, as claimed by Kukhanova et al. (1983), nor, on the other hand, do the data presented here prove that lycorine specifically inhibits ascorbic acid biosynthesis (Arrigoni et al., 1975). We must now check the ability of yeasts to split lycorine and study whether yeasts do actually have an ascorbic acid system.     

Use of potassium depletion to assess adaptation of ruminal bacteria to ionophores.

When mixed ruminal bacteria from cattle fed timothy hay were suspended in a medium containing a low concentration of potassium, monensin and lasalocid catalyzed a rapid depletion of potassium from cells. The ionophore-mediated potassium depletion was concentration dependent, and it was possible to describe the relationship with saturation constants. Mixed ruminal bacteria never lost more than 50% of their potassium (Kmax = 46%), and the concentrations of monensin and lasalocid needed to cause half-maximal potassium depletion (Kd) were 178 and 141 nM, respectively. When cattle were fed 350 mg of monensin per day, the ratio of ruminal acetate to propionate decreased from 4.2 to 2.9, and the Kd of monensin was eightfold greater than the value for mixed ruminal bacteria from control animals. Monensin supplementation also caused a twofold increase in the Kd of lasalocid. Lasalocid supplementation (350 mg per day) had no effect on the ruminal acetate-to-propionate ratio, but it caused a twofold increase in the Kd values of monensin and lasalocid. Increases in Kd occurred almost immediately after ionophore was added to the ration, and the Kd values returned to their prefeeding values within 14 days of withdrawal. Ionophore supplementation had no effect on the Kmax values, and approximately 50% of the population was always highly ionophore resistant. Because the Kd values of even adapted ruminal bacteria were low (< 1.5 microM), it appears that a large proportion of the ruminal ionophore is bound nonselectively to feed particles or ionophore-resistant bacteria.     

Differential regulation of the immune response to SRBC by monoclonal antibodies to interferon-gamma

Three monoclonal antibodies against different epitopes of interferon-gamma (IFN-gamma) were used to assess its role as a normal immunomodulatory molecule. Two of these antibodies were able to reduce significantly the primary antibody response to sheep erythrocytes in an in vitro culture system. One of these two antibodies has been reported to suppress both the antiviral and macrophage activation factor activities of IFN-gamma by binding to its carboxyl terminus. These findings indicate that IFN-gamma is an important lymphokine for the maximum expression of the immune response and that it acts via the carboxyl terminus of the molecule. This antibody suppressed the immune response only when added at the initiation of culture, suggesting that the action of IFN-gamma is on an early component of the response. The third monoclonal antibody, which binds to the amino end of IFN-gamma, did not suppress the in vitro response. However, it was able to block the effects exerted by an immunosuppressive dosage of exogenous IFN-gamma on in vitro antibody production. These results indicate that the immunosuppression vitro antibody production. These results indicate that the immunosuppression induced by the addition of IFN-gamma to a primary antibody response and the role that it plays in that response are mediated through different sites on the molecule and, therefore, probably by different mechanisms.     

Covalent binding of eicosanoids to platelet proteins

Following an incubation of washed human platelets with 14C-arachidonic acid, a small fraction of the radioactivity became tightly bound to the protein pellet. Three criteria suggested that it was actually a covalent binding: it was not removed by exhaustive extractions with solvents of various polarities, it was not dialysable against SDS-buffer and it corresponded to the labeling of several protein bands after SDS-polyacrylamide gel electrophoresis. The use of several pharmacological agents (indomethacin, eicosatetraynoic acid, dazoxiben, diamide) has allowed us to divide this binding into three components: the first one, independent from both cyclooxygenase and lipoxygenase, the second one dependent on cyclooxygenase products and finally the third one, dependent on lipoxygenase products.     

What's History Got to Do with It? A Response to Seddon's Definition of Reintroduction

A recent article in Restoration Ecology by Philip Seddon aims at unraveling the definitions of various types of species translocations—from reintroductions to assisted colonization—and points out the slippery slope of misused words. I argue here that defining reintroduction is not as straightforward as Seddon presents it. Commonly used definitions of what constitutes a reintroduction all include some reference to “historical” conditions, but what exactly that encompasses is left open. I examine two parts of the reintroduction confusion: first, how the guidance documents and laws define reintroduction and second, how these definitions might be interpreted when reintroductions are presented in public forums. Rather than moving away from reintroductions toward interventions of other names, I encourage scientists to use a broad definition of reintroduction presented by the IUCN to open up reintroduction as a viable label for bringing a species back to an area regardless of when it was previously there or why it became extinct.     

从生命伦理到生命法

20世纪下半叶以来,生命科技的发展极大地增进了人类的福祉,但也引生了大量伦理与法律问题,使得生命科技的伦理调整与法律规范成为必然。在生命科技发展的过程中,生命伦理发挥了重要的引领作用,它以其自身特定的机制保障着生命科技的健康发展。生命伦理与生命法存在着明显区别,这些区别使得生命伦理在现代生命科技社会中无法独立承担引领生命科技健康发展的使命,而必须与生命法共同在生命科技社会治理中发挥作用。在现代生命科技社会中,生命法具有不可取代的重要作用,正是基于此,20世纪70年代以来,各国兴起了一场生命伦理法律化的运动,纷纷强化了本国的生命法制建设,改变了以往单纯依赖生命伦理调整生命科技活动的历史,使法律也参与到生命科技的规制中来。人类生命科技治理必然要经历一个由单纯依赖生命伦理到依赖生命法与生命伦理相结合的发展阶段。当前,我国生命立法还存在诸多不足,难以适应生命科技发展的现实需要,需要采取相应的完善对策。     

New Threats to Academic Freedom

Using a specific case as an example, the article argues that the Internet allows dissemination of academic ideas to the general public in ways that can sometimes pose a threat to academic freedom. Since academic freedom is a fundamental element of academia and since it benefits society at large, it is important to safeguard it. Among measures that can be taken in order to achieve this goal, the publication of anonymous research seems to be a good option.     

Covalent binding of eicosanoids to platelet proteins

Following an incubation of washed human platelets with ¹⁴C-arachidonic acid, a small fraction of the radioactivity became tightly bound to the protein pellet. Three criteria suggested that it was actually a covalent binding: it was not removed by exhaustive extraction with solvents of various polarities, it was not dialysable against SDS-buffer and it corresponded to the labeling of several protein bands after SDS-polyacrylamide gel eletrophoresis. The use of several pharmacological agents (indomethacin, eicosatetraynoic acid, dazoxiben, diamide) has allowed us to divide this binding into three components : the first one, independent from both cyclooxygenase and lipoxygenase, the second one dependent on cyclooxygenase products and finally the third one, dependent on lipoxygenase products.     

Conformation of gramicidin in relation to its ability to form bilayers with lysophosphatidylcholine

The ability of gramicidin to induce bilayer formation in lysophosphatidylcholine (LPC) systems was investigated as a function of the conformation of the peptide. The conformation was varied by using different solvents to cosolubilize gramicidin and lipid. Using circular dichroism (CD), it was found that when codissolved in trifluoroethanol (TFE), after drying and subsequent hydration, gramicidin is mainly present in the single-stranded beta 6.3-helical configuration, whereas when using chloroform/methanol or ethanol as the solvent, it is proposed that the dominant conformation of gramicidin in the membrane is that of the double-stranded antiparallel dimer. Employing 31P NMR, the stoichiometry for bilayer formation was found to be 6 to 7 lipid molecules per gramicidin monomer, when samples were prepared from TFE, whereas a stoichiometry of 4 was found when chloroform/methanol or ethanol was the solvent. Upon heating the latter samples, a conversion was observed in the CD pattern toward that indicative of the beta 6.3-helical configuration. This change was accompanied by an increase in the extent of bilayer formation. Next, it was investigated whether the conformation of gramicidin and its ability to induce bilayer formation were dependent on the lipid acyl chain length. CD measurements of samples prepared from TFE indicated that gramicidin, independent of acyl chain length, was present in the beta 6.3-helical configuration but the intensity of the ellipticities at 218 nm increased with the length of the acyl chain. The extent of bilayer formation in these samples was found to be largely chain length independent.(ABSTRACT TRUNCATED AT 250 WORDS)     

Results of the introduction of Coregonids to Lake Vashozero

The results of the introduction of coregonids—the whitefish Coregonus lavaretus and the European cisco C. albula—to Lake Vashozero are considered. It is shown that a positive result was obtained from the introduction of the European cisco; it has naturalized in the lake and successfully reproduces. The biology of the European cisco in a water body new for it was studied, and it was compared to its initial form from Onega Lake. The structure of trophic relations in the water body has changed with the introduction of the European cisco. Previously there was one flow of matter and energy in the lake: benthos—benthophagous fish—carnivorous fish. Now, however, another flow has been added: plankton—European cisco—carnivorous fish.     

Failure of medullary carcinoma of the thyroid to respond to doxorubicin therapy

We describe 3 patients with metastatic medullary carcinoma of the thyroid who were treated with doxorubicin hydrochloride (Adriamycin). Serum calcitonin was measured before and after doxorubicin therapy. Doxorubicin failed to arrest the progression of the disease in any of the patients. Although serum calcitonin levels dropped in 1 patient during therapy, they remained markedly elevated in all 3 patients. From the present series it appears that medullary thyroid carcinoma often does not have a response to doxorubicin.     

From proteomic inventory to architecture

Electron tomography can provide three-dimensional reconstructions of large pleomorphic structures at molecular resolution. While the principles of electron tomography have been known for decades, its use has gathered momentum only in recent years. Technological advances have made it possible to apply it to ice-embedded biological material (cryotomography), thereby ensuring a close-to-life preservation of the samples. In combination with advanced computational methods, such as molecular identification based on pattern recognition, it is a promising approach to comprehensively map macromolecular architecture inside organelles and cells and to visualize macromolecules at work in their natural environment.     

Binding of methotrexate to dihydrofolate reductase and its relation to protonation of the ligand

Stopped-flow spectrophotometry and stopped-flow fluorometry have been used to study the binding of methotrexate (MTX) and 3-deazamethotrexate (3-deazaMTX) to dihydrofolate reductase (DHFR) isoenzymes from Streptococcus faecium and from Lactobacillus casei. The absorbance change and fluorescence quenching that occur when MTX binds to DHFR isoenzyme II from S. faecium (SFDHFR II) are both biphasic and give similar apparent rate constants for both phases. The faster phase has an apparent rate constant that is dependent on MTX concentration and therefore corresponds to the initial binding reaction. From the concentration dependence it has been calculated that the association rate constant is 3.0 X 10(5) M-1 s-1 at 20 degrees C and pH 7.3, and the association constant (equilibrium constant) under these conditions is 5.8 X 10(5) M-1. By examination of the amplitude of the fast-phase absorbance change at various wavelengths, it has been determined that the absorbance change occurring in the fast phase is due to MTX protonation. Within the limits of the method it was thus not possible to detect a difference in the rates of binding and of protonation of MTX. The MTX association rate constant is pH dependent, decreasing 330-fold as the pH is decreased from 5.0 to 9.0. The data fit well to a curve generated by assuming a single ionization with a pKa of 6.0 and a pH-independent association rate constant 1000-fold greater for binding of protonated MTX to SFDHFR II than for binding of unprotonated MTX.(ABSTRACT TRUNCATED AT 250 WORDS)