Colicin biology.

Colicins are proteins produced by and toxic for some strains of Escherichia coli. They are produced by strains of E. coli carrying a colicinogenic plasmid that bears the genetic determinants for colicin synthesis, immunity, and release. Insights gained into each fundamental aspect of their biology are presented: their synthesis, which is under SOS regulation; their release into the extracellular medium, which involves the colicin lysis protein; and their uptake mechanisms and modes of action. Colicins are organized into three domains, each one involved in a different step of the process of killing sensitive bacteria. The structures of some colicins are known at the atomic level and are discussed. Colicins exert their lethal action by first binding to specific receptors, which are outer membrane proteins used for the entry of specific nutrients. They are then translocated through the outer membrane and transit through the periplasm by either the Tol or the TonB system. The components of each system are known, and their implication in the functioning of the system is described. Colicins then reach their lethal target and act either by forming a voltage-dependent channel into the inner membrane or by using their endonuclease activity on DNA, rRNA, or tRNA. The mechanisms of inhibition by specific and cognate immunity proteins are presented. Finally, the use of colicins as laboratory or biotechnological tools and their mode of evolution are discussed.     

Colicin Biology

Colicins are proteins produced by and toxic for some strains of Escherichia coli. They are produced by strains of E. coli carrying a colicinogenic plasmid that bears the genetic determinants for colicin synthesis, immunity, and release. Insights gained into each fundamental aspect of their biology are presented: their synthesis, which is under SOS regulation; their release into the extracellular medium, which involves the colicin lysis protein; and their uptake mechanisms and modes of action. Colicins are organized into three domains, each one involved in a different step of the process of killing sensitive bacteria. The structures of some colicins are known at the atomic level and are discussed. Colicins exert their lethal action by first binding to specific receptors, which are outer membrane proteins used for the entry of specific nutrients. They are then translocated through the outer membrane and transit through the periplasm by either the Tol or the TonB system. The components of each system are known, and their implication in the functioning of the system is described. Colicins then reach their lethal target and act either by forming a voltage-dependent channel into the inner membrane or by using their endonuclease activity on DNA, rRNA, or tRNA. The mechanisms of inhibition by specific and cognate immunity proteins are presented. Finally, the use of colicins as laboratory or biotechnological tools and their mode of evolution are discussed.     

Mechanisms of killing spores of Bacillus subtilis by acid, alkali and ethanol

AIMS: To determine the mechanisms of killing of Bacillus subtilis spores by ethanol or strong acid or alkali. METHODS AND RESULTS: Killing of B. subtilis spores by ethanol or strong acid or alkali was not through DNA damage and the spore coats did not protect spores against these agents. Spores treated with ethanol or acid released their dipicolinic acid (DPA) in parallel with spore killing and the core wet density of ethanol- or acid-killed spores fell to a value close to that for untreated spores lacking DPA. The core regions of spores killed by these two agents were stained by nucleic acid stains that do not penetrate into the core of untreated spores and acid-killed spores appeared to have ruptured. Spores killed by these two agents also did not germinate in nutrient and non-nutrient germinants and were not recovered by lysozyme treatment. Spores killed by alkali did not lose their DPA, did not exhibit a decrease in their core wet density and their cores were not stained by nucleic acid stains. Alkali-killed spores released their DPA upon initiation of spore germination, but did not initiate metabolism and degraded their cortex very poorly. However, spores apparently killed by alkali were recovered by lysozyme treatment. CONCLUSIONS: The data suggest that spore killing by ethanol and strong acid involves the disruption of a spore permeability barrier, while spore killing by strong alkali is due to the inactivation of spore cortex lytic enzymes.SIGNIFICANCE AND IMPACT OF THE STUDY: The results provide further information on the mechanisms of spore killing by various chemicals.     

Immunotherapy of cervical cancer as a biological dissipative structure

Cervical cancer can be not only prevented, but also effectively treated. Decreased efficiency of biochemical, neurohormonal and/or immunological mechanisms leads to infectious states which, irrespective of their bacterial, viral or parasitic aetiology, are only the necessary, but not the sufficient causes of neogenesis. The cause of cancer is the natural and common phenomenon of the self-organization of systems, endangered by ending of their existence, into more efficient time-space structures at the expense of their surrounding. Infected cells or infectiously changed tissues in their final phase of existence are often recognized as a precancerous state, but their genome does not differ from other organism cells, and that is why the carcinogenesis can still be prevented by direct fighting of pathogenic microorganisms, and indirectly by strengthening the body by neurohormonal therapy or vaccine immunopotentialization. Primary prophylaxis of neoplasms requires that not only the dissipathogenic state of cells be prevented, but also their tissue surrounding be normalized to head off the risk of the self-organization of neoplastic forms of life, differing in their genetic identity from the surrounding cells. Lactovaginal immunopotentialization complements the conservative and operative methods of oncological treatment, as well as has prophylactic application in women with the history of miscarriages, premature deliveries, lack of or significantly shortened lactation, neurohormonal menstruating disorders, chronic and recurrent inflammations of the reproductive organs, long-term hormonal contraception and hormone replacement therapy during menopause, or only deficiency of Lactobacillus vaginalis, as indicators of risk of cervical cancer.     

Maternal ‘imprinting’ or maternal ‘labelling’ in goats?

The present study on maternal ‘imprinting’ in goats initially failed to replicate previous findings that mothers discriminate between their own and alien young, accepting their own kid and rejecting alien kids. Rather, 62% of the mothers accepted both their own and alien kid. This disparity was not due to breed differences, age, or behaviour of the aliens but to length of time the alien kids had been with their own mother. When behaviour was eliminated through anaesthesia or left intact, older aliens that had had no contact with their mother were accepted by other mothers, while those aliens with more than 8 h of contact with their own mothers were rejected (whether anaesthetized or not) by other mothers. Maternal ‘imprinting’ in goats may take longer than previously reported, and mothers may ‘label’ their kids and learn to recognize the labels.     

Dispersal in Marine Organisms without a Pelagic Larval Phase

In contrast to marine organisms whose offspring go through an extended planktonic stage, the young of others develop directly into benthic juveniles or into yolky nonfeeding larvae that spend only a few hours in the plankton before settling. Yet, paradoxically, many such species have geographic distributions that are comparable to those with a pelagic dispersal stage. This article reviews some of the ways in which these organisms can expand their distributions: drifting, rafting, hitchhiking, creeping, and hopping. Drifting applies to species in which larvae may be short-lived, but adults can detach or be detached from their benthic substratum and be passively carried to new areas, floating at the water's surface or below it. Many encrusting species and mobile species can spread by rafting, settling on natural or artificial floating substrata which are propelled by wind and currents to new regions. Hitchhiking applies to those attaching to vessels or being carried in ballast water of ships to a distant region in which their offspring can survive. Other marine species extend their distributions by hopping from one island of hard substratum or favorable sedimentary microhabitat to another, while creeping species extend their distributions along shores or shelves where habitats remain similar for long distances.     

Macrophage spreading in vitro. III. The effect of metabolic inhibitors, anesthetics and other drugs on spreading induced by subtilisin

The effect of certain drugs on macrophage spreading induced by the proteolytic enzyme sub-tilisin was quantitatively examined and the 50 and 90 % inhibitory concentrations of the drugs were determined. In most instances the viability of the macrophages was preserved, as shown by phagocytic tests and by experiments in which cells pretreated with the drugs and washed were shown to spread when exposed to subtilisin. Inhibitors of electron transport, oxidative phosphorylation or uncouplers at rather small concentrations all effectively blocked macrophage spreading, indicating an ATP requirement. Spreading was also inhibited by neutral or cationic anesthetics and the reciprocal of their 50 % inhibitory concentrations was linearly related to their octanol-water partition coefficients. Inhibition by the anesthetics paralleled their effects on other membrane phenomena, such as nerve conduction, osmotic lysis of erythrocytes, viral induced cell fusion, or Sarcoma I cell to substrate adhesion, also suggesting a membrane target. Spreading was reduced by the anti-inflammatories indomethacin, or phenylbutazone, by high doses of colchicine or vinblastine, by the putative microfilament-acting drug cytochalasin B or by the SH- reagent n-ethyl maleimide. Colchicine and vinblastine effects may involve mechanisms other than their microtubular actions. Several other drugs, including inhibitors of protein synthesis, did not inhibit the spreading of macrophages. Spreading induced by substrate-bound immune complexes was also inhibited by representative metabolic inhibitors or anesthetics.     

Proteins of hepatitis B surface antigen.

Purified 22-nm forms of hepatitis B surface antigen (Hbsag) representing the three major antigenic subtypes (adw, ayw, and adr) were analyzed for their constituent polypeptides by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. No consistent difference in either the number or relative distributions of the polypeptides was observed for the various subtypes. Seven polypeptides were designated as P-1 through P-7 in order of their decreasing mobilities. By comparison with protein standards, their molecular weights were estimated as 23, 29.5, 36, 41.5, 53.5, 72, and 97 thousand. The P-1 and P-2 components represented the major polypeptides; P-2 and P-5 might by glycoproteins, based on their reaction with periodic acid-Shiff reagent. Each polypeptide contains cysteine residues. HBSAg was radiolabeled with 3H or 14C by reductive methylation or iodinated with 125I by the chloramine-T or lactoperoxidase procedures. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of labeled HBSAg yielded patterns identical to those obtained with protein stain. Comparison of HBSAg labeled by the chloramine-T and lactoperoxide procedures indicated that there was no distinction between internal or external components within the 22-nm structure.     

Evolution in the pentastomids

The Pentastomida, or tongue worms, form an aberrant group of annulated endoparasites little known to most parasitologists and veterinarians. Although there is no doubt of their affiliation to arthropods, textbooks often rank the Pentastomida as a separate phylum. Riley's many publications on the group have 'promoted it from the realm of the completely unknown to the semi-obscure', but still much research is needed on their basic biology, as little is known about their biochemistry, ecology or their evolutionary relationships. This review by Rolf Haugerud is intended to inspire curiosity about the Pentastomida by discussing their evolution in relation to their phylogeny, host relationships, geographic distribution, transmission and impact.     

RNA and DNA aptamers in cytomics analysis.

BACKGROUND: The systematic evolution of ligands by exponential enrichment (SELEX) technique is a combinatorial library approach in which DNA or RNA molecules (aptamers) are selected by their ability to bind their protein targets with high affinity and specificity, comparable to that of monoclonal antibodies. In contrast to antibodies conventionally selected in animals, aptamers are generated by an in vitro selection process, and can be directed against almost every target, including antigens like toxins or nonimmunogenic targets, against which conventional antibodies cannot be raised. METHODS: Aptamers are ideal candidates for cytomics, as they can be attached to fluorescent reporters or nanoparticles in order to study biological function by fluorescence microscopy, by flow cytometry, or to quantify the concentration of their target in biological fluids or cells using ELISA, RIA, and Western blot assays. RESULTS: We demonstrate the in vitro selection of anti-kinin B1 receptor aptamers that could be used to determine B1 receptor expression during inflammation processes. These aptamers specifically recognize their target in a Northern-Western blot assay, and bind to their target protein whenever they are exposed in the membrane. CONCLUSIONS: Currently, aptamers are linked to fluorescent reporters. We discuss here the present status and future directions concerning the use of the SELEX technique in cytomics.     

Reglucosylation by UDP-glucose:glycoprotein glucosyltransferase 1 delays glycoprotein secretion but not degradation

UDP-glucose:glycoprotein glucosyltransferase 1 (UGT1) is a central quality control gatekeeper in the mammalian endoplasmic reticulum (ER). The reglucosylation of glycoproteins supports their rebinding to the carbohydrate-binding ER molecular chaperones calnexin and calreticulin. A cell-based reglucosylation assay was used to investigate the role of UGT1 in ER protein surveillance or the quality control process. UGT1 was found to modify wild-type proteins or proteins that are expected to eventually traffic out of the ER through the secretory pathway. Trapping of reglucosylated wild-type substrates in their monoglucosylated state delayed their secretion. Whereas terminally misfolded substrates or off-pathway proteins were most efficiently reglucosylated by UGT1, the trapping of these mutant substrates in their reglucosylated or monoglucosylated state did not delay their degradation by the ER-associated degradation pathway. This indicated that monoglucosylated mutant proteins were actively extracted from the calnexin/calreticulin binding-reglucosylation cycle for degradation. Therefore trapping proteins in their monoglucosylated state was sufficient to delay their exit to the Golgi but had no effect on their rate of degradation, suggesting that the degradation selection process progressed in a dominant manner that was independent of reglucosylation and the glucose-containing A-branch on the substrate glycans.     

How mothers find their pups in a colony of Antarctic fur seals

In Antarctic fur seals, Arctocephalus gazella, mothers must identify their own young among hundreds or even thousands of pups, if they are to invest in their own offspring and avoid misdirecting their parental care. When returning to their breeding colony from a foraging trip of several days at sea, mothers have to find and identify their young before suckling can occur. There appears to be little confusion about which pup belongs to a mother, and adoption is absent or rare. Using behavioral observations, we investigated the means by which female Antarctic fur seals identified their pups in a breeding colony of about 750 mother-pup pairs on Kerguelen Island. We evaluated the importance of vision, scent communication, vocalizations, and rendezvous locations as possible explanations of how mothers find their pups. Every pup that a mother examined, whether her own or not, exchanged naso-nasal inspection with her, suggesting a strong role for olfactory communication in individual recognition. Both mothers and pups called to each other, and mothers that searched for pups over a longer period gave more calls and encountered more pups. Thus, vocalizations may have been used to attract pups that might be offspring. Nursing usually occurred in the same place from the end of one maternal visit to the colony and the arrival at the beginning of the next visit, suggesting that nursing locations may serve as a meeting place, or rendezvous, for mothers and pups. These results suggest that finding pups is a two-stage process for females, in which pups for sampling are attracted by calls or examined at the previous nursing location, and then individual identification is made by olfactory cues.     

Apprehension and Pedagogy in Evolution Education

Instructors’ apprehensions and the decisions instructors make about pedagogy are often linked when it comes to teaching evolution. Whether it is the reticence of K-12 teachers that their instruction may affect their students’ religious beliefs detrimentally or that they may become caught up in some administrative, media, parental, or school political turmoil or whether it is the apprehension of college students who perceive that their religious beliefs are being explicitly challenged, such fears can be reduced by understanding their roots and by honing pedagogy in ways that reduce perceived threats. This article describes why it is prudent to address these often secretly held apprehensions and how to help instructors feel free to employ their best pedagogical methods to teach evolution without lingering fear. Some suggestions are given for pre-college and college instructors interested in combining effective pedagogy with as little perceived threat as possible. Methods are offered that allow instructors to focus on underlying scientific misconceptions even if those misconceptions are ultimately facilitated by non-scientific sources, while giving creationist or creationist-leaning students a chance to learn the appropriate scientific conceptions without their religious beliefs being explicitly threatened in a science course.     

Tolerance to manganese toxicity among cultivars of lucerne (Medicago sativa L.)

Two sand culture experiments were carried out to identify commercial cultivars of lucerne or alfalfa (Medicago sativa L.) which contain elite, Mn-tolerant plants for use in a selection programme to increase the acid-soil tolerance of this perennial legume. Differences in Mn tolerance, both within and between cultivars, were observed when a range of cultivars were exposed to regular waterings with dilute nutrient solution containing 20 or 25 mg Mn L^–1. Under these moderately toxic regimes, the winter dormant cultivars Cimmaron and WL 318 were found to contain elite plants that had greater dry matter yields than their mean cultivar yield under non-toxic Mn conditions.Cultivars which contained elite, Mn-tolerant plants could not be identified by phenotypic characteristics such as their height or their toxicity symptom score, nor by their winter dormancy class. Possible reasons for the occurrence of elite plants in these cultivars are discussed. The elite, high yielding Mn-tolerant plants could not be identified from the other plants within their cultivar population by their Mn toxicity symptoms nor by their height.     

The Immediate Source of the Oviposition-Deterring Pheromone Produced by Larvae of Adalia bipunctata (L.) (Coleoptera, Coccinellidae)

As is the case for other insects ovipositing on or in resources that are limited in time and/or space, the two-spot ladybird beetle, Adalia bipunctata (L.) produces an oviposition-deterring pheromone (ODP), which is produced by the larval stages. Foraging larvae touch the substrate with their tarsi and the anal disk on the tenth abdominal segment. The aim of this paper was to determine whether the ODP produced by larvae was deposited by the tarsi or the anal disk. Fourth instar larvae either had their anal disk and tarsi, or anal disk, or tarsi coated with a water-soluble mounting medium. Larvae so treated were allowed to walk on filter paper that was subsequently presented to gravid females. The tracks of larvae that had both their tarsi and anal disk masked did not inhibit oviposition. However, the tracks of larvae that had only their tarsi masked significantly inhibited oviposition but those of larvae that had only their anal disk masked did not. It is concluded that the ODP is deposited on the substrate by the anal disk on the tenth abdominal segment of larvae.     

Reported versus measured adult statures

Reported and measured statures were obtained for 100 husband-wife pairs. In addition, wives were asked to specify whether their husbands were tall, medium, or short. Correlations between reported and measured statures are high (0.84–0.97) and wives tend to overestimate their own measured stature by about 1 cm, and that of their husbands by about 1.3 cm. Wives correctly classify their husbands as tall, medium, or short in about 70% of the cases, using terciles of the stature distribution of American men as the standard. Reported statures may be useful proxies for measured statures for certain purposes. In the absence of measured or reported statures, a wife's categorization of her husband as tall, medium, or short may be satisfactory for some group studies.     

Hypolipidemic and antioxidant effects of curcumin and capsaicin in high-fat-fed rats

The beneficial hypolipidemic and antioxidant influences of the dietary spice compounds curcumin and capsaicin were evaluated. Curcumin, capsaicin, or their combination were included in the diet of high-(30%)-fat-fed rats for 8 weeks. Dietary high-fat-induced hypertriglyceridemia was countered by dietary curcumin, capsaicin, or their combination by 12%-20%. Curcumin, capsaicin, and their combination also produced a slight decrease in serum total cholesterol in these animals. Serum alpha-tocopherol content was increased by dietary curcumin, capsaicin, and their combination in high-fat-fed rats. Serum total thiol content in high-fat-fed animals and serum ascorbic acid in normal animals was elevated by the combination of curcumin and capsaicin. Hepatic glutathione was increased by curcumin, capsaicin, or their combination in normal animals. Hepatic glutathione and alpha-tocopherol were increased, whereas lipid peroxide level was reduced by dietary curcumin and combination of curcumin and capsaicin in high-fat-fed animals. Serum glutathione peroxidase and glutathione transferase in high-fat-fed rats were generally higher as a result of dietary curcumin, capsaicin, and the combination of curcumin and capsaicin. Hepatic glutathione reductase and glutathione peroxidase were significantly elevated by dietary spice principles in high-fat-fed animals. The additive effect of the 2 bioactive compounds was generally not evident with respect to hypolipidemic or antioxidant potential. However, the effectiveness of the combination was higher in a few instances.     

Adaptation versus pleiotropy: why do males harm their mates?

Recent studies have documented male traits that cause physicalharm to their mates during copulation. Such harm has been suggestedto either (1) arise as a negative pleiotropic side effect ofadaptations that give males a reproductive advantage in anothercontext or (2) represent a male adaptation per se. In otherwords, male traits that cause harm to their mates may becomeestablished despite the fact that they cause harm or becausethey do so. A critical assumption of the latter hypotheses isthat females respond to infliction of harm in a manner thatis beneficial to their mates: by reducing their propensity toremate and/or by elevating their current reproductive rate.In the present study, we test this assumption by experimentallyinflicting various forms of harm to females immediately aftercopulation in three different insect species. We reveal thatfemales do not delay remating or increase their reproductiverate after being harmed but, on the contrary, remate soonerand lay fewer eggs in some cases. We conclude that selectionfor infliction of harm to females per se is unlikely. Instead,available empirical evidence supports the hypothesis that harmfulmale traits arise as negative pleiotropic side effects of adaptationsthat yield other selective advantages to males during reproductivecompetition.     

Relationship between cell-mediated and humoral immune attack on tumor cells: II. The role of cellular lipid metabolism and cell surface charge in the outcome of immune attack

Treatment of P815 tumor cells with adriamycin increased their sensitivity to killing by anti-P815 antibody plus C, but not by allogeneic P815-sensitized spleen cells. Conversely, mitomycin C treatment enhanced the cells' sensitivity to cell-mediated, but not antibody-C, killing. Hydrocortisone, but not epinephrine, was effective in increasing the resistance of the cells to killing by both antibody-C and cell-mediated attack systems. The ability of the tumor cells to resist antibody-C killing correlated with their ability to incorporate fatty acid into complex cellular lipid; no such correlation was found between the cellular lipid synthesis and tumor cell susceptibility to cell-mediated killing. Drug or hormone-treated tumor cells exhibited unique changes in cellular lipid synthesis and composition and in cell surface physical properties that correlated with their susceptibility to antibody-C or cell-mediated attack. Cells increased in their sensitivity to antibody-C killing exhibited a decreased cholesterol:phospholipid mole ratio. In contrast, cells rendered more sensitive to cell-mediated killing exhibited an increase in polar phospholipid content and a measurable decrease in net negative cell surface charge density. These data implicate unique chemical and/or physical properties of tumor cells to be of fundamental importance for their ability to resist either humoral or cell-mediated immunologic attack; modulation of one or another of these cellular properties results in a change in the cells' susceptibility to immune killing by antibody plus C or by cytotoxic T lymphocytes.