Maintenance and mass rearing of phytoseiid predators of the cassava green mite

The cassava green mite Mononychellus tanajoa (Bondar), accidentally introduced from South America into Africa, has spread across the cassava belt and is causing severe yield losses to cassava. Biological control was recognized as the most promising and sustainable strategy against this pest. Among the different stages of a biological control program, mass rearing of beneficials is often a major bottleneck. The different rearing systems used by the International Institute of Tropical Agriculture are described. A mother culture system maintains pure and high quality colonies and provides inoculum to start mass production. Twenty biotypes are maintained separately and no contamination has been found in the cultures. Oligophagous species are reared in the insectary on artificial substrate, using alternative prey as a food source. For phytoseiid species specific to M. tanajoa, an on plant system is used in a greenhouse. Advantages and disadvantages of the two different systems are discussed as well as general requirements and constraints in rearing phytoseiids.     

In vitro fenoprofenyl–coenzyme a thioester formation: Interspecies variations

In vitro coenzyme A thioester formation from (?)-(R)-fenoprofen (FPF) and palmitic acid has been studied using liver microsomes from rat, guinea pig, sheep, and dog. In every species with both palmitic acid or (?)-(R)-fenoprofen, the Lineweaver–Burk plot was linear in the substrate concentration range used and as a consequence agrees with the involvement of only one isoenzyme (or different isoenzymes of similar K_m values). The V_max values for the thioesterification of (?)-(R)-fenoprofen present large species variations from 2.1 ± 1.0 with sheep liver microsomes to 60.6 ± 11 nmol/min/mg with dog liver microsomes. These values statistically significantly correlate (r = 0.94) to the V_max values observed when palmitic acid was used as a substrate. Furthermore palmitic acid inhibited (?)-(R)-fenoprofen–CoA formation in the same extent in all animal species. The stereoselectivity of the thioesterification was also species dependent. © 1995 Wiley-Liss, Inc.     

Molecular definition of an allelic series of mutations disrupting the myostatin function and causing double-muscling in cattle

We have determined the entire myostatin coding sequence for 32 double-muscled cattle sampled from ten European cattle breeds. Seven DNA sequence polymorphisms were identified, of which five would be predicted to disrupt the function of the protein, one is a conservative amino acid substitution, and one a silent DNA sequence variant. Four additional DNA sequence polymorphisms were identified in myostatin intronic sequences. In all but two breeds, all double-muscled animals were either homozygous or compound heterozygotes for one of the five loss-of-function mutations. The absence of obvious loss-of-function mutations in the coding sequence of the two remaining breeds points either towards additional mutations in unexplored segments of the gene, or towards locus heterogeneity of double-muscling. Received: 20 September 1997 / Accepted: 11 October 1997     

Intermediate Filament Disassembly in Cultured Dorsal Root Ganglion Neurons Is Associated with Amino-Terminal Head Domain Phosphorylation of Specific Subunits

Abstract: We previously reported that activation of protein kinase A in cultured rat dorsal root ganglion neurons, treated concomitantly with low concentrations of okadaic acid that selectively inhibit protein phosphatase-2A, enhanced the Triton X-100 solubility of neurofilament triplet proteins. We now show that peripherin and α-internexin follow the same fragmentation profile as the neurofilament subunits, consistent with the notion that all five cytoplasmic intermediate filament proteins in these neurons form an integrated filamentous network whose assembly can be modulated by protein kinase A. Similar to the situation previously observed for the light neurofilament subunit, there was a strong correlation between phosphorylation of the amino-terminal head domain of peripherin and filament fragmentation. In contrast, insignificant levels of ³²P were incorporated into α-internexin under conditions promoting disassembly, indicating that phosphorylation of this protein is not involved directly in filament fragmentation. The situation for the mid-sized neurofilament subunit (NFM) was not as clear-cut. Phosphopeptide mapping of NFM revealed many head and tail domain phosphorylation sites. However, changes in NFM head domain phosphorylation under conditions promoting filament disassembly were not as pronounced as for peripherin.     

A liver-type mutation in a case of pronounced erythrocyte phosphofructokinase deficiency without clinical expression

A marked erythrocyte phosphofructokinase deficiency was detected in a healthy man. His enzymatic activity was only 25% that of normal controls. His father and his son had erythrocytic phosphofructokinase activities of 50-55% that of normal controls. The chromatographic separation of erythrocytic phosphofructokinase isozymes, as well as immunological studies revealed a decrease in L-type phosphofructokinase activity. The lowered erythrocytic L-type phosphofructokinase activity was not accompanied by a decreased level of L-type phosphofructokinase in proteins. The L/M subunit ratio was similar to that of normal subjects. The defect resulted from the synthesis of stable L-type mutant subunit with high electrophoretic mobility. White blood cells, which synthesize mostly the same isozyme as L-type phosphofructokinase also showed a decreased activity and a high electrophoretic mobility. In spite of this important deficiency, and of significant metabolic alterations (a slight decrease in ATP; 2,3-diphosphoglycerate; triose phosphate), hemolysis did not appear in the propositus.     

Inhibitory effects of cysteamine on neuroendocrine function

The action of cysteamine on anterior pituitary hormone secretion was studied in vivo using conscious, freely moving male rats and in vitro using anterior pituitary cells in monolayer culture. Administration of 500 micrograms cysteamine into the lateral cerebral ventricles of normal rats caused the complete inhibition of pulsatile GH secretion for a minimum of 6 h. This treatment also significantly decreased plasma concentrations of LH for at least 6 h in orchiectomized rat, TSH in short-term (0.5 month) thyroidectomized rats, and PRL in long-term (6 months) thyroidectomized rats. The in vivo stimulation of GH, LH, TSH and PRL with their respective releasing hormones 60 min after administration of cysteamine was not different from the response observed in rats pretreated with saline except for PRL where cysteamine pretreatment significantly inhibited the expected PRL increase. In vitro, 1 mM cysteamine decreased basal and TRH stimulated PRL release while not affecting basal or stimulated GH, LH, TSH and ACTH secretion. These data demonstrate the dramatic and wide-ranging effects of cysteamine on anterior pituitary hormone secretion. This action appears to be mediated through hypothalamic pathways for GH, LH and TSH and through a pituitary pathway for PRL.     

Population bottlenecks: influence on mitochondrial DNA diversity and its effect in coregonine stock discrimination

This study was designed to test the hypothesis that anadromous populations of North American whitefish, Coregonus clupeaformis (Mitchill), believed to have suffered more intense population bottlenecks during past glaciation events, should reveal less mitochondrial DNA (mtDNA) variability and population-genetic structuring than anadromous populations of European whitefish, C. lavaretus (L.). C. clupeaformis exhibited extremely low levels of diversity and population structuring, in terms of number and frequency of clonal lines as well as sequence divergence estimates, as compared with populations of C. lavaretus. These results support the hypothesis that the severity of population bottlenecks related to Pleistocene glaciation events may be largely responsible for the level of mtDNA variability observed. This in turn influences the sampling strategy required to maximize the usefulness of mtDNA analysis in stock discrimination.