Protein phosphatases in higher plants: multiplicity of type 2A phosphatases in Arabidopsis thaliana

Two DNA fragments, AP-1 and AP-2, encoding amino acid sequences closely related to Ser/Thr protein phosphatases were amplified from Arabidopsis thaliana genomic DNA. Fragment AP-1 was used to screen. A. thaliana cDNA libraries and several positive clones were isolated. Clones EP8a and EP14a were sequenced and found to encode almost identical proteins (97% identity). Both proteins are 306 amino acids in length and are very similar (79–80% identity) to the mammalian isotypes of the catalytic subunit of protein phosphatase 2A. Therefore, they have been designated PP2A-1 and PP2A-2. A third cDNA clone, EP7, was isolated and sequenced. The polypeptide encoded (308 amino acids, lacking the initial Met codon) is 80% identical with human phosphatases 2A and was named PP2A-3. The PP2A-3 protein is extremely similar (95% identity) to the predicted protein from a cDNA clone previously found in Brassica napus. Southern blot analysis of genomic DNA using AP-1 and AP-2 probes, as well as probes derived from clones EP7, EP8a and EP14a strongly indicates that at least 6 genes closely related to type 2A phosphatases are present in the genome of A. thaliana. Northern blot analysis using the same set of probes demonstrates that, at the seedling stage, the mRNA levels for PP2A-1, PP2A-3 and the gene containing the AP-1 sequence are much higher than those of PP2A-2 and AP-2. These results demonstrate that a multiplicity of type 2A phosphatases might be differentially expressed in higher plants.     

Patterns in the composition and richness of helminth communities in brown trout, Salmo trutta, in a group of reservoirs

Helminth community composition and richness were studied in brown trout, Salmo trutta , in 10 reservoirs of broadly similar age and characteristics situated close to each other in a well-defined region of south-west England. Communities were compared using cluster and ordination analyses, and possible correlations between helminth richness and a number of environmental variables were investigated. The hypothesis that the helminth communities should show high degrees of similarity and that large differences between reservoirs and a high degree of clustering would be unrecognizable was refuted. Levels of community similarity were low and comparable to those determined for helminths in salmonids in natural lakes. Trout in some reservoirs exhibited very distinctive helminth faunas and clustering of reservoirs was apparent. No single factor, including reservoir size and presence of piscivorous birds, had a predominant influence on community richness or composition but rather a multiplicity of local factors was believed to influence these parameters. The results indicate that local factors promoting distinctiveness have a greater influence on the composition and richness of fish helminth communities in lakes and reservoirs than do regional factors promoting similarity.     

The evolution of long interspersed repeated DNA (L1, LINE 1) as revealed by the analysis of an ancient rodent L1 DNA family

Summary All modern mammals contain a distinctive, highly repeated (⩾50,000 members) family of long interspersed repeated DNA called the L1 (LINE 1) family. While the modern L1 families were derived from a common ancestor that predated the mammalian radiation ∼80 million years ago, most of the members of these families were generated within the last 5 million years. However, recently we demonstrated that modern murine (Old World rats and mice) genomes share an older long interspersed repeated DNA family that we called Lx. Here we report our analysis of the DNA sequence of Lx family members and the relationship of this family to the modern L1 families in mouse and rat. The extent of DNA sequence divergence between Lx members indicates that the Lx amplification occurred about 12 million years ago, around the time of the murine radiation. Parsimony analysis revealed that Lx elements were ancestral to both the modern rat and mouse L1 families. However, we found that few if any of the evolutionary intermediates between the Lx and the modern L1 families were extensively amplified. Because the modern L1 families have evolved under selective pressure, the evolutionary intermediates must have been capable of replication. Therefore, replicationcompetent L1 elements can reside in genomes without undergoing extensive amplification. We discuss the bearing of our findings on the evolution of L1 DNA elements and the mammalian genome.     

A family of serine protease genes expressed in adult buffalo fly (Haematobia irritans exigua)

Gene fragments encoding serine proteases expressed in adult buffalo fly (Haematobia irritans exigua) were amplified from cDNA using generic oligonucleotide PCR primers, based on conserved residues surrounding the active-site His and Ser amino acids found in all serine proteases. The PCR product consisted of a broad band extending from about 450 by to 520 bp, which suggested that the PCR product actually consisted of numerous DNA fragments of slightly variable sizes. Seventeen independent clones of these fragments, each with an insert of approximately 480 bp, were digested with HaeIII. Comparison of restriction fragment patterns indicated that 13 of these clones harboured different PCR products. This was confirmed by DNA sequence analysis of 9 clones. Each of the sequenced clones contained an open reading frame which included structurally conserved regions characteristic of the serine protease superfamily. This study reveals the expression of a large and highly variable repertoire of serine proteases in adult buffalo fly. Importantly, these data also demonstrate the utility of such an approach in obtaining DNA probes for use in further investigations of gene family organization and expression, as well as providing recombinant antigens in the form of fusion proteins which may be used as candidates for vaccine production.     

Genetic studies of water buffalo blood markers. I. Red cell acid phosphatase,albumin, catalase,red cell α-esterase-3, group-specific component,and protease inhibitor

We have developed the methodologies for typing and family studies to establish the modes of inheritance of water buffalo red cell acid phosphatase (Acp), protease inhibitor (Pi), and group-specific component (Gc) on isoelectric focusing and albumin (Alb), red cell -esterase-3 (Est-3), and catalase (Cat) on polyacrylamide gel electrophoresis. Family studies showed that Pi, Gc, Alb, and Cat are coded by autosomal genes with two codominant alleles, while Est-3 is autosomal with two codominant alleles and a recessive null allele and Acp exhibits three codominant alleles.This project was funded by the Australian Centre for International Agricultural Research through Grant PN 8364 and the Malaysian programme for Intensification of Research in Priority Areas through Grant IRPA 1-07-05-057.     

Changing household financial strategies: Canadian couples today

In Canada, there has been a marked increase in the relative frequency of dual earner families, and especially of dual career families, compared to breadwinner/homemaker families. Effects of this change on the handling of incomes inside the household are examined here. In this paper, quantitative survey data and qualitative data on strategies of financial management are described and analyzed for co-resident couples in Winnipeg. Findings are presented on control over income, financial possession, and access to household money. These findings are interpreted as evidence of a shift in the form of companionate marriage toward greater equality of economic agency. It is suggested that the most common household financial strategy among Canadian couples today is that of flexible shares.     

The role of fire in terrestrial vertebrate richness patterns

Productivity is strongly associated with terrestrial species richness patterns, although the mechanisms underpinning such patterns have long been debated. Despite considerable consumption of primary productivity by fire, its influence on global diversity has received relatively little study. Here we examine the sensitivity of terrestrial vertebrate biodiversity (amphibians, birds and mammals) to fire, while accounting for other drivers. We analyse global data on terrestrial vertebrate richness, net primary productivity, fire occurrence (fraction of productivity consumed) and additional influences unrelated to productivity (i.e., historical phylogenetic and area effects) on species richness. For birds, fire is associated with higher diversity, rivalling the effects of productivity on richness, and for mammals, fire's positive association with diversity is even stronger than productivity; for amphibians, in contrast, there are few clear associations. Our findings suggest an underappreciated role for fire in the generation of animal species richness and the conservation of global biodiversity.     

Vegetation change in acidic dry grasslands in Moravia (Czech Republic) over three decades: Slow decrease in habitat quality after grazing cessation

Aims

Shallow soils on acidic bedrock in dry areas of Central Europe support dry grasslands and heathlands that were formerly used as extensive pastures. These habitats are of high conservation value, but their abandonment in the 20th century triggered slow natural succession that poses a threat to specialized plant species. We asked how this vegetation and its plant diversity have changed over the past three decades and whether protected areas have positively affected habitat quality.

Location

Southwestern and central Moravia, Czech Republic.

Methods

In 2018–2019, we resurveyed 94 vegetation plots first sampled in 1986–1991 at 47 acidic dry grassland and heathland sites. We compared the number of all vascular plant species, Red List species and alien species per plot using parametric and non-parametric tests, life-form spectra using the chi-square test, species composition using detrended correspondence analysis, and indicator values using a permutation test. We also compared these changes between sites within and outside protected areas.

Results

Vegetation changes over the past three decades have been relatively small. However, we detected a decrease in total species richness, the number of Red List species and the number of characteristic species of dry grasslands. Neophytes were infrequent, while archaeophytes increased slightly. The competitive tall grass Arrhenatherum elatius, annual species and young woody plants increased in abundance or newly established at many sites. Indicator values did not change except for a slight increase in nutrient values. These negative trends occurred both within and outside protected areas but were more pronounced outside.

Conclusions

Formerly grazed acidic dry grasslands and heathlands in Moravia are slowly losing habitat specialists, including threatened plant species, and are increasingly dominated by Arrhenatherum elatius. Conservation management, especially cutting in protected areas, slows down the negative trends of decline in plant diversity and habitat quality but is insufficient to halt these processes completely.