Reproduction in mice: Protein kinase mimics the sperm effect on preimplantation embryo development

The creation of an environment in mouse fallopian tubes that is sufficient to sustain preimplantation embryo development is known to require the participation of spermatozoa in excess of those involved in the process of fertilization. We have now found that highly purified cAMP-dependent protein kinase can substitute for spermatozoa in the facilitation of the first cleavage of mouse embryos. Both spermatozoa and purified protein kinase induce increases in fallopian phosphoproteins. It is suggested that nonfertilizing spermatozoa could exert their effects on preimplantation embryo development through the provision of protein kinase.     

Mechanism of Copper Resistance in a Copper Mine Isolate Pseudomonas putida Strain S4

The mechanism of copper resistance in a multiple-metal-resistant natural isolate Pseudomonas putida strain S4 is based on inducible efflux. Active extrusion of copper ions occurs from the cytoplasm during the exponential phase of growth. Involvement of ATPase in the efflux of copper ions has been demonstrated by employing specific inhibitors. The effluxed copper is not thrown out of the cell, but remains in a bound form (to a protein) in the periplasm. Thus, a balance between the intracellular level, to fulfill the metabolic requirements, and the periplasmic sequestration, to evade toxicity, is maintained by this isolate. Received: 11 February 2002 / Accepted: 7 March 2002     

Evaluation of potential trap plant species for the wheat bug Nysius huttoni (Hemiptera: Lygaeidae) in forage brassicas

1. The wheat bug Nysius huttoni is a major pest of brassica seedlings. Management of this insect currently relies on seed treatment with neonicotinoids and spraying with chlorpyrifos and pyrethroid insecticides. These practices can generate severe external costs, including human health, the environment and biodiversity. Trap cropping is one alternative option to protect brassica seedlings from N. huttoni.
2. Trap crop species evaluated in field cage experiments were: alyssum (Lobularia maritima L. Desvauxcv. Benthamii White), wheat (Triticum aestivum L. cv. Morph), coriander (Coriandrum sativum L. cv. Santo) and clover (Trifolium repens L. cv. Nomad). These were compared with kale (Brassica oleracea L. cv. Kestrel). In open‐field experiments, alyssum (L maritima), wheat (T. aestivum) and a mixture of alyssum (L. maritima) and wheat (T. aestivum) were used. All of these were compared to kale (B. oleracea).
3. Alyssum and wheat were the most favoured potential trap plants for N. huttoni. Results indicated that two treatments: alyssum (used as a single trap crop) or ‘alyssum plus wheat’ (a multiple trap crop), may be useful in brassica fields to protect the seedlings from N. huttoni damage.
4. Such a trap cropping protocol potentially reduces pesticide use in forage brassicas and can also deliver multiple ecosystem services such as biological control of insect pests.

     

A new method of measurement of permeability of lipid membranes

A new method, based on potential measurements to obtain permeabilities and mobilities of ionic species passing through membranes, under the influence of concentration gradients is proposed. This method is applied to three different lipid membranes in aqueous KCl solutions. The values of permeabilities and mobilities obtained by this simple method is in good agreement with those reported in literature     

Mechanism to combat cobalt toxicity in cobalt resistant mutants of <Emphasis Type="Italic">Aspergillus nidulans</Emphasis>

Characteristics of fungal species tolerant to high levels of metals in natural environment can be amplified by isolation and selection of resistant mutants. Step-by-step culturing led to identification of highly stable Co-resistant (Co^R) mutants of A. nidulans. Based on two distinct morphological features, Co-resistant mutants were categorized as Co^RI and Co^RII. The two mutants varied in their growth behavior and colony morphology that were reflected in supplemented as well as unsupplemented growth media over the generations. As compared to the Co^RI, Co^RII mutant exhibited sparse mycelia and conidiation but secreted higher amount of melanin. Co^R mutants could tolerate up to 2.5mM Co in the medium, however, required a threshold concentration of 0.25mM Co for optimal growth and germination. Absence of Co in the medium caused a stressful situation for the Co^R mutants and led to the secretion of a white extracellular precipitate found to be a glycoprotein. In response to interactions with Co-ions, Co^R mutants produced oxalic acid and bioprecipitated Co as Co-oxalate providing scope for metal reclamation as well as oxalic acid extraction. The mutants could help to recover the insoluble Co-oxalate salt from aqueous solutions by entrapping it in their growing mycelial meshwork.