Relationship between osmoprotection and the structure and intracellular accumulation of betaines by Escherichia coli

Abstract Naturally occuring betaines, especially glycine betaine and proline betaine, were accumulated by Escherichia coli from urine. In synthetic hyperosmotic medium, with an homologous series of added betaines, (CH₃)₃N⁺-(CH₂) _n -COO⁻, osmoprotective activity and intracellular accumulation decreased monotonically as n increased from 1 to 5. In contrast, α -substituted glycine betaines were accumulated in a similar manner to glycine betaine, but with different osmoprotective activities. Arsenobetaine, with a quaternary arsonium group, was also accumulated but amino acids which can become negatively charged in a chemically basic environment were not.     

Relationship between chimpanzee Rh-like genes and the R-C-E-F blood group system

The antigenic closeness between the chimpanzee alloantigen R^c of the R-C-E-F system, and the human alloantigen Rh_o(D) suggests a phylogeconnection between their genes. To confirm at the molecular level the common origin of these genes, genomic DNA from 16 unrelated chimpanzees of various R-C-E-F phenotypes were digested by three restriction enzymes and analyzed by Southern blot using a human Rh cDNA probe and three exon-specific probes. Restrictions profiles displayed reach polymorphism. Correlations between some bands and certain R-C-E-F phenotypes demonstrate that the human Rh cDNA probe defines in chimpanzee genomic DNA some genes of the R-C-E-F system.     

Leukaemia inhibitory factor and the regulation of pre-implantation development of the mammalian embryo

This paper reviews the evidence that certain growth factors, particularily leukaemia inhibitory factor (LIF), play a crucial role in regulating the development of the pre-implantation mammalian embryo. LIF was originally implicated in regulating the early development of the mouse embryo because it inhibited the differentiation of embryonic stem (ES) cells, pluripotential cells derived from the inner cell mass of the blastocyst. Subsequent studies on its role in vivo revealed, surprisingly, that it is essential for the growth rather than the differentiation of the blastocyst. In vivo, overtly normal blastocysts can be produced in a LIF-deficient environment that are capable of forming viable fertile adults. However, in the absence of LIF, they fail to implant and enter into a state resembling that exhibited by blastocysts undergoing delayed implantation, which is characterized by a cessation of cell proliferation. This failure to implant occurs because the principle sites of LIF production are the endometrial glands of the uterus. These synthesize and secrete LIF at implantation, with LIF synthesis essential for implantation. Preliminary evidence indicates that LIF synthesis is required both by the uterus for it to undergo decidualization and by the blastocyst for implantation. These data indicate that the maternal environment plays a crucial role in the development and growth of the pre-implantation embryo, by supplying factors that regulate these processes in the embryo. © 1994 Wiley-Liss, Inc.     

Fasciola hepatica: A secreted cathepsin L-like proteinase cleaves host immunoglobulin

Adult Fasciola hepatica secrete a cysteine proteinase capable of cleaving host IgG close to the papain cleaving site. The proteinase was separated by size permeation chromatography. Gelatinsubstrate polyacrylamide gel electrophoresis analysis revealed that the proteinase migrates as 6 proteolytic bands in the apparent molecular size range 60–90 kDa. Based on pH profiles of activity, inhibition studies using diethylpyrocarbonate and the diazomethylketone Z-phe-ala-CHN₂, and characterising the substrate specificity of the enzymes using fluorogenic peptide substrates we have shown that the 60–90-kDa proteinases are cathepsin L-Iike proteinases.     

Angiotensin II Type 1 Receptor mRNA Levels in the Brains of Normotensive and Spontaneously Hypertensive Rats

Abstract: The type 1 angiotensin II (All) receptor (AT₁-R) has been implicated in the physiological actions mediated by All in the brain. In view of the reported hyperactivity of the brain All system in the spontaneously hypertensive rat (SHR), we compared the expression of AT,-R mRNAs in the brains of normotensive [Wistar Kyoto (WKY)] and SHR animals. Northern blot analysis showed about three- and ∼20-fold increases in the levels of AT₁-R mRNAs from the hypothalamus and brainstem areas, respectively, of the SHR compared with the WKY rat brain. This was attributable to greater levels of both AT,_1A- and AT,_1B-R mRNA subtypes in these areas from the SHR. These observations suggest that increased All receptor levels in SHR brain may, in part, be a result of increased expression of the AT₁-R gene.     

Purification and Properties of an S-Adenosylmethionine: 2,4-Disubstituted Phenol O-Methyltransferase from Phanerochaete chrysosporium

An enzyme catalyzing the O-methylation of acetovanillone (3-methoxy-4-hydroxyacetophenone) by S-adeno-sylmethionine was isolated from Phanerochaete chrysosporium and purified 270-fold by ultrafiltration, anion-exchange chromatography, and gel filtration. The enzyme exhibited a pH optimum between 7 and 9 and was rapidly denatured at temperatures above 55°C. The K_m values for acetovanillone and S-adenosylmethionine were 34 and 99 μM, respectively. S-Adenosylhomocysteine acted as a powerful competitive inhibitor of S-adenosylmethionine, with a K_i of 41 μM. The enzyme was also susceptible to inhibition by thiol reagents and low concentrations of heavy metal ions. Gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the enzyme was monomeric and had a molecular weight of approximately 53,000. Substrate specificity studies showed that 3-methoxy- and 3,5-dimethoxy-substituted 4-hydroxy-benzaldehydes, -benzoic acids, and -acetophenones were the preferred substrates for the enzyme. The corresponding 3,4-dihydroxy compounds were methylated relatively slowly, while the 3-hydroxy-4-methoxy compounds were almost inactive as substrates. Substituents in both the 2 and 4 positions relative to the hydroxyl group appeared to be essential for significant enzyme attack of a substrate. Provided that certain steric criteria were satisfied, the nature of the substituent was not critical. Hence, xenobiotic compounds such as 2,4-dichlorophenol and 2,4-dibromophenol were methylated almost as readily as acetovanillone. However, an extended side chain in the 4 position was not compatible with activity as a substrate, and neither homovanillic, caffeic, nor ferulic acid was methylated. The substrate range of the O-methyltransferase tends to imply a role in the catabolism or detoxification of lignin degradation products such as vanillic and syringic acids.     

Accumulation of the β-subunit of polygalacturonase 1 in normal and mutant tomato fruit

Polyclonal antiserum raised against the native PG1 isoform of tomato fruit (Lycopersicon esculentum Mill.) polygalacturonase [poly(1,4--d-galacturonide) glycanohydrolase, EC 3.2.1.15] bound to each of the subunits of the protein and also to a range of other fruit proteins. Affinity purification was used to remove antibody molecules that bound to the native form of the PG2 isoform. The resulting serum bound to native PG1, denatured PG2 and -subunits of PG1 but not to native PG2 or other fruit proteins. This anti-PG1 serum was used to monitor the occurrence of the PG1 -subunit and PG2 in detergent extracts of tomato tissues. The -subunit polypeptide was detected in pericarp but not locule tissue of fruit, including fruit of the rin and nor mutants. It increased in amount in the pericarp tissues from an early stage to the mature green stage, clearly prior to any appreciable accumulation of the PG2 subunit. The -subunit polypeptide was not detected in stem or leaf tissues. A PG2-specific antiserum was used to study the interaction of PG2 with the isolated -subunit. The PG2 isoform was bound to the -subunit over a wide range of salt concentrations and pH; the interaction was independent of the presence of reducing agents. It is concluded that strong non-covalent forces are involved in the interaction. The results are consistent with a model in which the -subunit is positioned in the cell wall structure and provides a specific binding site for the active PG2 subunit when this is synthesised during ripening.Abbreviations B breaker - MG mature green - M_r relative molecular mass - nor non-ripening mutant - PAGE polyacrylamide gel electrophoresis - PG polygalacturonase - rin ripening inhibitor mutant - SDS sodium dodecyl sulphate     

Utilisation of a tropical bay as a nursery area by sharks of the families Carcharhinidae and Sphyrnidae

Synopsis At least eight species of sharks of the families Carcharhinidae and Sphyrnidae use Cleveland Bay in northern Australia as a communal nursery area.Carcharhinus dussumieri, C. fitzroyensis, C. limbatus andC. tilstoni use the bay as a seasonal primary nursery, with juveniles occurring in it for only a few months each year immediately after birth. Alternatively,Carcharhinus sorrah, Rhizoprionodon acutus andR. taylori use the bay as a year-round primary and secondary nursery, with juveniles remaining in it up to the size at maturity. AdultR. taylori also persist in the bay, a behavioural pattern possibly explained by their small maximum size. While present immediately after birth the type of utilisation pattern displayed bySphyrna lewini could not be clarified in this study. Although diets of these species in the bay are similar, there is probably little direct competition for food due to the highly productive habitats in the bay supporting an abundance of food resources. The highest numbers of juveniles occur when prey species are the most abundant, and when temporal separation of some seasonally-occurring species of sharks in effect.     

Age and growth of the Australian sharpnose shark,Rhizoprionodon taylori,from north Queensland,Australia

Synopsis Age and growth were studied inRhizoprionodon taylori using specimens caught in Cleveland Bay, North Queensland, Australia. Von Bertalanffy growth parameters were estimated using three different techniques: vertebral ageing, back calculation and length frequency. Vertebrae from 138 specimens were sectioned and narrow circuli counted to estimate age. Marginal increment analysis verified that circuli were produced annually in late summer, probably as a result of stress during the mating season. The oldest female was 7 and male 6 years old. Von Bertalanffy growth parameters estimated from vertebral ageing data for males were t_O = 0.410 yr, K = 1.337, L = 652.2 mm, and for females t_O = 0.455 yr, K = 1.013 and L = 732.5 mm. Growth parameters determined by length frequency and back calculation techniques concurred with those from vertebral ageing. Growth of the 0+ age class was very rapid, averaging 140% of the size at birth in the first year. Males and females matured after only one year, the lowest age at maturity reported in the family Carcharhinidae. Annual growth increments decreased rapidly after maturity, and little growth occurred after three years.     

Joyful by nature: approaches to investigate the evolution and function of joy in non-human animals

The nature and evolution of positive emotion is a major question remaining unanswered in science and philosophy. The study of feelings and emotions in humans and animals is dominated by discussion of affective states that have negative valence. Given the clinical and social significance of negative affect, such as depression, it is unsurprising that these emotions have received more attention from scientists. Compared to negative emotions, such as fear that leads to fleeing or avoidance, positive emotions are less likely to result in specific, identifiable, behaviours being expressed by an animal. This makes it particularly challenging to quantify and study positive affect. However, bursts of intense positive emotion (joy) are more likely to be accompanied by externally visible markers, like vocalisations or movement patterns, which make it more amenable to scientific study and more resilient to concerns about anthropomorphism. We define joy as intense, brief, and event-driven (i.e. a response to something), which permits investigation into how animals react to a variety of situations that would provoke joy in humans. This means that behavioural correlates of joy are measurable, either through newly discovered ‘laughter’ vocalisations, increases in play behaviour, or reactions to cognitive bias tests that can be used across species. There are a range of potential situations that cause joy in humans that have not been studied in other animals, such as whether animals feel joy on sunny days, when they accomplish a difficult feat, or when they are reunited with a familiar companion after a prolonged absence. Observations of species-specific calls and play behaviour can be combined with biometric markers and reactions to ambiguous stimuli in order to enable comparisons of affect between phylogenetically distant taxonomic groups. Identifying positive affect is also important for animal welfare because knowledge of positive emotional states would allow us to monitor animal well-being better. Additionally, measuring if phylogenetically and ecologically distant animals play more, laugh more, or act more optimistically after certain kinds of experiences will also provide insight into the mechanisms underlying the evolution of joy and other positive emotions, and potentially even into the evolution of consciousness.