Mute Swans in Great Britain: a review,current status and long-term trends

We review the recent history of the Mute Swan in Great Britain and discuss the factors known to be affecting the population. Following a rise in the national population during the 1950s, numbers decreased sharply during the 1960s, and changed relatively little between 1970/71 and 1984/85. However, there has been considerable regional variation in the fortunes of Mute Swan populations during this period, with dramatic declines in some areas. Although several factors were thought to be contributing to such declines, poisoning from the ingestion of lead fishing weights was shown to be the largest single cause of death amongst swans in a number of areas. Voluntary measures to address this problem were initiated in 1982 and culminated in the banning by law of use of lead weights in 1987.Winter counts were used to investigate the current status and distribution of the Mute Swan in Great Britain and to examine long-term regional trends. The maximum total count reached 12600 birds in January 1990, which compares with an average of 9550 for the previous five winters. However, accounting for birds missed, the population may now number at least 25 000. Peak total numbers have mostly occurred in September, after which numbers remain approximately stable until December and then decline. Patterns of seasonal abundance vary between regions and habitats and these are discussed.The British population has increased dramatically since 1986/87 and reached its highest level for 27 years in 1987/88. There have been recent increases in most regions with record levels being reached mostly in 1987 or 1988, and there has been growth in the numbers on all habitat types, especially on reservoirs, gravel extraction pits and freshwater marshes. The timing of these increases corresponds very closely with the introduction of legislation against the use of lead fishing weights, and the incidence of lead poisoning is known to have been considerably reduced by such measures.     

CD and Fourier transform ir spectroscopic studies of peptides. II. Detection of β-turns in linear peptides

Comparative CD and Fourier transform ir (FTIR) spectroscopic data on N-Boc protected linear peptides with or without the (Pro-Gly) β-turn motif (e.g., Boc-Tyr-Pro-Gly-Phe-Leu-OH and Boc-Tyr-Gly-Pro-Phe-Leu-OH) are reported herein. The CD spectra, reflecting both backbone and aromatic contributions, were not found to be characteristic of the presence of β-turns. In the amide I region of the FTIR spectra, analyzed by self-deconvolution and curve-fitting methods, the β-turn band shewed up between 1639 and 1633 cm^?1 in trifluoroethanol (TFE) but only for models containing the (Pro-Gly) core. This band war-also present in the spectra in chloroform but absent in dimethylsulfoxide. These findings, in agreement with recent ir data on cyclic models and 3₁₀-helical polypeptides and protein in D₂O [see S. J. Prestrelski, D. M. Byler, and M. P. Thompson (1991), International Journal of Peptide and Protein Research, Vol. 37, pp. 508–512; H. H. Mantsch, A. Perczel. M. Hollósi, and G. D. Fasman (1992), FASEB Journal, Vol. 6, p. A341; H. H. Mantsch. A. Perczel, M. Hollósi, and G. Fasman (1992), Biopolymers. Vol. 33, pp. 201–207; S. M. Miick, G. V. Martinez, W. R. Fiori, A. P. Tedd, and G. L. Millhauser (1992). Nature, Vol. 359, pp. 653–655], suggest that the amide I band, with a major contribution from the acceptor C ? O of the 1 ← 4 intramolecular H bond of β-turns, appears near or below 1640 cm^?1, rather than above 1660 cm^?1. In TFE, bands between 1670 and 1660 cm^?1 are mainly due to “free” carbonyls, that is, C ? O's of amides that are solvated but not involved in the characteristic H bonds of periodic secondary structures or β-turns. © 1994 John Wiley & Sons, Inc.     

Extracts from MDX and normal mouse skeletal muscle contain similar levels of mitogenic activity for myoblasts

The mdx mouse has been used as an animal model for human Duchenne muscular dystrophy (DMD). Unlike DMD, skeletal muscles of mdx mice undergo successful regeneration and do not show extensive fibrosis and functional impairment. Growth factors have been proposed to be involved in muscle growth and regeneration. We compared mitogenic activity for skeletal myoblasts released after injury in mdx and control mice, using crushed muscle extract (CME) as a model system. We found that CMEs from normal and mdx mice contained similar mitogenic activities per microgram protein, and produced similar maximal levels of mitogenic stimulation. Skeletal muscles from mdx mice, however, released higher amounts of CME protein per gram of muscle weight compared to controls, possibly as a result of histological or physiological alterations in mdx muscle tissue. Adequate mitogenic activity in CME from mdx muscles may be related to successful muscle regeneration in mdx mice.     

Interaction between the black yeast Aureobasidium pullulans and the gall midge Lasioptera ephedricola in gall formation on the desert shrub Ephedra trifurca

Galls produced by the cecidomynd Lastoptera ephedncola on Ephedia trifurca always have a black ring associated with them while galls produced by the congener L ephedrae never do Black ring material after microscopic examination and culture proved to be Aureobasidium pullulans In addition to lacking black ring material neither L ephedrae galls nor healthy stems consistently yielded Aureobasidium on culture Gall and larva size measurements indicated that continued larval presence is not necessary for gall development, suggesting fungus initiated gall formation However inoculation of healthy stems with Aureobasidium caused lesions hut not galls The mycelium m galls did not appear grazed and neither larvae nor pupae contained Aureobasidium propagules suggesting that larvae do not feed directly on fungi These data also suggest that there is no trans-pupal passage of fungus from larvae or pupae to adults Newly emerged females do not carry fungal propagules suggesting that thcy are not inoculated upon exiting the gall Gall position leaf culture and stem culture data suggest that the fungus is picked up from leaves prior to oviposition     

Physical mapping of inhibin β-A in domestic cattle

The gene for the -A subunit of inhibin (INHBA) was assigned to bovine syntenic group U13 by bovine x rodent hybrid somatic cells and the polymerase chain reaction (PCR). A 482-bp PCR fragment was used to clone a 37-kb cosmid. This cosmid was assigned to bovine Chromosome (Chr) 4 (BTA 4) by fluorescence in situ hybridization (FISH). This is the first assignment of a U13 marker to a bovine chromosome. A restriction fragment length polymorphism (RFLP) was detected with PstI within the INHBA cosmid.     

Characterization of the T, L, I, S, M and P cell surface (immobilization) antigens of Tetrahymena thermophila: molecular weights, isoforms, and cross-reactivity of antisera.

In the ciliate protist Tetrahymena thermophila the L, H, T, I, S, M and P cell surface proteins (immobilization antigens) are expressed under different conditions of temperature (L, H, T), culture media (I, S), and mutant genotype (M, P). Immunoblot and autoradiographic studies using antisera to purified protein show that the molecular weights of these proteins range from 25,000 to 59,000. The H, T, S, M and P antigens are recognized as single polypeptides, whereas L, I, and one allelic form of T each appear to consist of a family of polypeptides. Although antisera are specific in immobilization and immunofluorescence assays of surface protein in living cells, cross-reactivity is seen with denatured protein on immunoblots. It is hypothesized that the surface protein genes are organized into families of evolutionarily related isoloci.     

Biochemistry and pharmacology of 7α-substituted androstenediones as aromatase inhibitors

The inhibition of aromatase, the enzyme responsible for converting androgens to estrogens, is therapeutically useful for the endocrine treatment of hormone-dependent breast cancer. Research by our laboratory has focused on developing competitive and irreversible steroidal aromatase inhibitors, with an emphasis on synthesis and biochemistry of 7α-substituted androstenediones. Numerous 7α-thiosubstituted androst-4-ene-3,17-diones are potent competitive inhibitors, and several 1,4-diene analogs, such as 7α-(4′-aminophenylthio)-androsta-1,4-diene-3,17-dione (7α-APTADD), have demonstrated effective enzyme-activated irreversible inhibition of aromatase in microsomal enzyme assays. One focus of current research is to examine the effectiveness and biochemical pharmacology of 7α-APTADD in vivo. In the hormone-dependent 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat mammary carcinoma model system, 7α-APTADD at a 50 mg/kg/day dose caused an initial decrease in mean tumor volume during the first week, and tumor volume remained unchanged throughout the remaining 5-week treatment period. This agent lowers serum estradiol levels and inhibits ovarian aromatase activity. A second research area has focused on the synthesis of more metabolically stable inhibitors by replacing the thioether linkage at the 7α position with a carbon-carbon linkage. Several 7α-arylaliphatic androst-4-ene-3,17-diones were synthesized by 1,6-conjugate additions of appropriate organocuprates to a protected androst-4,6-diene or by 1,4-conjugate additions to a seco-A-ring steroid intermediate. These compounds were all potent inhibitors of aromatase with apparent K_is ranging between 13 and 19 nM. Extension of the research on these 7α-arylaliphatic androgens includes the introduction of a C₁---C₂ double bond in the A-ring to provide enzyme-activated irreversible inhibitors. The desired 7α-arylaliphatic androsta-1,4-diene-3,17-diones were obtained from their corresponding 7α-arylaliphatic androst-4-ene-3,17-diones by oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). These inhibitors demonstrated enzyme-mediated inactivation of aromatase with apparent k_inacts ranging from 4.4 × 10⁻⁴ to 1.90 x 10⁻³ s⁻¹. The best inactivator of the series was 7α-phenpropylandrosta-1,4-diene-3,17-dione, which exhibited a T_1/2 of 6.08 min. Aromatase inhibition was also observed in MCF-7 human mammary carcinoma cell cultures and in JAr human choriocarcinoma cell cultures, exhibiting IC₅₀ values of 64-328 nM. The 7α-arylaliphatic androgens thus demonstrate potent inhibition of aromatase in both microsomal incubations and in choriocarcinoma cell lines expressing aromatase enzymatic activity. Additionally, the results from these studies provide further evidence for the presence of a hydrophobic binding pocket existing near the 7α-position of the steroid in the active site of aromatase. The size of the 7α-substituent influences optimal binding of steroidal inhibitors to the active site and affects the extent of enzyme-mediated inactivation observed with androsta-1,4-diene-3,17-dione analogs.     

Of mice and wrens: the relation between abundance and geographic range size in British mammals and birds

We examine the relation between population size and geographic range size for British breeding birds and mammals. As for most other assemblages studied, a strong positive interspecific correlation is found in both taxa. The relation is also recovered once the phylogenetic relatedness of species has been controlled for using an evolutionary comparative method. The slope of the relation is steeper for birds than for mammals, but this is due in large part to two species of mammals that have much higher population sizes than expected from their small geographic ranges. These outlying mammal species are the only ones in Britain to be found only on small offshore islands, and so may be exhibiting density compensation effects. With them excluded, the slope of the abundance–range size relation for mammals is not significantly different to that for birds. However, the elevation of the relation is higher for mammals than for birds, indicating that mammals are approximately 30 times more abundant than birds of equivalent geographic range size. An earlier study of these assemblages showed that, for a given body mass, bats had abundances more similar to birds than to non-volant mammals, suggesting that the difference in abundance between mammals and birds might be due to constraints of flight. Our analyses show that the abundance–range size relation for bats is not different for that from other mammals, and that the anomalously low abundance of bats for their body mass may result because they have smaller than expected geographic extents for their size. Other reasons why birds and mammals might have different elevations for the relation between population size and geographic range size are discussed, together with possible reasons for why the slopes of these relations might be similar.     

Analysis of Orthologous Retrovirus-Like Elements in the White-Footed Mouse,Peromyscus leucopus

Three loci in the genome of the white-footed mouse, Peromyscus leucopus, were examined for the presence or absence of orthologous copies of the retrovirus-like element mys using polymerase chain reaction. We examined these loci in 28 mice collected throughout the P. leucopus species range. Mys insertions were present in only one of the individuals examined at the mys-1 and mys-7 loci. Conversely, the mys-6 element was found in several individuals, but the presence of this element was limited to northern latitudes. Because the long terminal repeats (LTRs) of a given element are expected to be identical at the time of retrotransposition into the genome, and to accumulate changes over evolutionary time, within-element LTR sequence comparisons can be used to estimate the relative age of insertions. Within-element LTR differences are greater in mys-6 than in mys-1 or mys-7. The LTRs from orthologous mys-6 elements of six mice were sequenced. The alignment revealed 13 of the 22 differences between the right and left LTRs that were shared by all orthologous mys-6 sites, suggesting that relative to its time of insertion into the genome, mys-6 has only recently spread across the northern part of the species range. Received: 23 January 1996 / Accepted: 24 April 1996