Species loss of stoneflies (Plecoptera) in the Czech Republic during the 20th century

1. Rapid expansion and intensification of anthropogenic activities in the 20th century has caused profound changes in freshwater assemblages. Unfortunately, knowledge of the extent and causes of species loss (SL) is limited due to the lack of reliable historical data. An unusual data set allows us to compare changes in the most sensitive of aquatic insect orders, the Plecoptera, at some 170 locations in the Czech Republic between two time periods, 1955–1960 and 2006–2010. Historical data (1890–1911) on assemblages of six lowland rivers allow us to infer even earlier changes. 2. Regional stonefly diversity decreased in the first half of the 20th century. Streams at lower altitudes lost a substantial number of species, which were never recovered. In the second half of the century, large‐scale anthropogenic pressure caused SL in all habitats, leading to a dissimilarity of contemporary and previous assemblages. The greatest changes were found at sites affected by organic pollution and a mixture of organic pollution and channelisation or impoundment. Colonisation of new habitats was observed in only three of the 80 species evaluated. 3. Species of moderate habitat specialisation and tolerance to organic pollution were most likely to be lost. Those with narrow specialisations in protected habitats were present in both historical and contemporary collections. 4. Contemporary assemblages are the consequence of more than a 100 years of anthropogenic impacts. In particular, streams at lower altitude and draining intensively exploited landscapes host a mere fragment of the original species complement. Most stonefly species are less frequently present than before, although their assemblages remain almost intact in near‐natural mountain streams. Our analyses demonstrate dramatic restriction of species ranges and, in some cases, apparent changes in altitudinal preference throughout the area.     

Computer simulations of glycolytic enzyme interactions with F-actin

Muscle actin and fructose-1,6-bisphosphate aldolase (aldolase) were chemically crosslinked to produce an 80 kDa product representing one subunit of aldolase linked to one subunit of actin. Hydroxylamine digestion of the crosslinked product resulted in two 40.5 kDa fragments, one that was aldolase linked to the 12 N-terminal residues of actin. Brownian dynamics simulations of muscle aldolase and GAPDH with F-actin (muscle, yeast, and various mutants) estimated the association free energy. Mutations of residues 1-4 of muscle actin to Ala individually or two in combination of the first four residues reduced the estimated binding free energy. Simulations showed that muscle aldolase binds with the same affinity to the yeast actin as to the double mutated muscle actin; these mutations make the N-terminal of muscle actin identical to yeast, supporting the conclusion that the actin N-terminus participates in binding. Because the depth of free energy wells for yeast and the double mutants is less than for native rabbit actin, the simulations support experimental findings that muscle aldolase and GAPDH have a higher affinity for muscle actin than for yeast actin. Furthermore, Brownian dynamics revealed that the lower affinity of yeast actin for aldolase and GAPDH compared to muscle actin, was directly related to the acidic residues at the N-terminus of actin.     

Interactions of glyceraldehyde-3-phosphate dehydrogenase with G- and F-actin predicted by Brownian dynamics

Brownian dynamics (BD) was used to simulate the binding of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) to G- and F-actin. High-resolution three-dimensional models (X-ray and homology built) of the proteins were used in the simulations. The electrostatic potential about each protein was predicted by solving the linearized Poisson-Boltzmann equation for use in BD simulations. The BD simulations resulted in complexes of GAPDH with G- or F-actin involving positively charged surface patches on GAPDH (Lyses 24, 69, 110 and 114) and negatively charged residues of the N- and C-termini (Asps 1, 25 and 363 and Glus 2, 4, 224 and 364) of actin. The actin residues all belong to subdomain 1. Although the positively charged surface patches of GAPDH are not close enough to each other to enhance their electrostatic potential, occasionally two subunits of the GAPDH tetramer may simultaneously interact with two neighboring monomers of F-actin. These results are different from those of fructose-1,6-bisphosphate aldolase, where quaternary structure directly influenced binding by two subunits combining their electrostatic potentials (see previous study, Ouporov et al., 1999, Biophys. J. 76: 17-27). Instead, GAPDH uses its quaternary structure to span the distance between two different actin subunits so that it can interact with two different actin subunits simultaneously.     

Evidence that primary infection of Charollais sheep with Toxoplasma gondii may not prevent foetal infection and abortion in subsequent lambings

A study carried out on a sheep farm examined whether Toxoplasma gondii foetal infection and associated abortion occur in successive lambings. We identified 29 ewes that gave birth to lambs on at least 2 successive years over our study period, 2000-2003. Tissue samples from the progeny of these ewes were analysed by PCR to determine infection status with T. gondii. T. gondii-infected lambs were born in 31% of successive pregnancies. T. gondii-positive lambs were aborted in successive pregnancies in 21% of lambings during study period, 2000-2003. The frequency of successive abortions within this flock over the period 1992-2003 was 18%. If a lamb was congenitally infected there was a high risk (69%) that the successive lamb from that ewe would also be congenitally infected. Similarly, if a lamb was aborted there was a high risk (55%) of abortion in the next lamb produced. These data suggest that life-long immunity to T. gondii infections may not always be acquired following an initial infection and raises the question as to whether the mechanisms of T. gondii transmission prior to and during ovine pregnancies are fully understood.     

Aspects of hadrosaurian cranial anatomy

Supraorbital bones in Saurolophus angustirostris are described, and their presence in all hadrosaurs is suggested. Frontal-nasal and premaxillar-nasal fontanellae are distinguished in hadrosaurs; their presence is explained as connected with growth and considered to he responsible for the variability of crest structures. New data indicating the presence of a cartilaginous diverticulum nasi within the circumnarial depression in Saurobphus ongustirostris are presented. A physiological (respiratory and/or thermoregulatory) function of the nasal diverticulum is proposed.     

Growth inhibition of selected food-borne bacteria, particularly Listeria monocytogenes, by plant extracts

C hung , K.-T., T homasson , W.R. & W u -Y uan , C.D. 1990. Growth inhibition of selected food-borne bacteria, particularly Listeria monocytogenes , by plant extracts. Journal of Applied Bacteriology 69 , 498–503.
Six extracts from Chinese medicinal plants: Tin Men Chu, Sey Lau Pai, Siu Mao Heung, Bak Tao Yung, Kam Chin Chiu and Liao Ya, were tested for their inhibitory effect on selected food-borne bacteria by the well assay technique. Among them, Tin Men Chu, Siu Mao Heung and Sey Lau Pai inhibited the growth of Staphylococcus aureus, Klebsiella pneumonia, Escherichia coli, Shigella flexneri, Streptococcus faecalis, Salmonella paratyphi, Salm. enteritidis, Enterobacter aero-genes, Pseudomonas fluorescens, Proteus vulgaris, Alcaligenes faecalis , and three strains of Listeria monocytogenes . Two of these three extracts, Tin Men Chu and Siu Mao Heung, suppressed the growth of L. monocytogenes Scott A in cabbage juice. This inhibition was prevented by the addition of protein but not sodium chloride. Plant extracts show potential to control the growth of food-borne bacteria.