Assumptions in tests for meiotic drive

Recent claims for the existence of meiotic drive in the ABO blood groups require the assumption of equal fertility (if there is no other selection operating) for the various mating types. There is evidence that does not support this assumption, and there are no convincing a priori grounds for making it.     

Shedding of the upper parts of grapevine shoots

Shedding of the upper parts of unlignified grapevine (Vitis vinifera L.) canes is frequent during autumn. Stress conditions during the growing-season lead to similar shedding of shoot tips. The separation process occurs above a node in the boundary area between the distal part of the diaphragm and the pith.Ethephon (2-chloroethyl-phosphonic acid) sprays, at 750 or 1500 mg l^?1, induced separation of the shoot tips of ‘Perlette’ and ‘Queen of the Vineyards’. Ethylene (C₂H₄) 200 vpm and ethephon at 10, 100 and 1000 mg l^?1 enhanced separation in shoot explants, whereas 2,4,5-TP (2,4,5-trichlorophenoxy-propionic acid) at concentrations above 1 mg l^?1 arrested it.This phenomenon may be regarded as a shoot abscission process which may represent adaptation of self-pruning of the grapevine.     

SURFACE CHEMISTRY OF THE HYDRANDEPTS AND ITS RELATION TO NITRATE ADSORPTION AS AFFECTED BY PROFILE DEPTH AND DEHYDRATION1

The pH₀ and ZPC of two Hydiandepts were determined by potentiomettic titiation in NaCl and by ion adsorption measurements from NH₄NO₃, respectively. The decrease of pH, pH₀, and ZPC due to drying was explained by the hydrolysis reaction. Partial drying, high organic matter content, and low Al₂ O₃ concentration in the surface soil were responsible for its low pH, pH₀ and ZPC. The high pH₀ of subsoils was attributed to the presence of amorphous aluminosilicates and mixed polymeric gels of Fe(III) and A1 with high water content. The significant decrease of nitrate adsorption due to dehydration is discussed in relation to the change in pH, pH₀, ZPC, and surface area on drying.     

Matrix metalloproteinases-2 and -9 activities in bovine follicular fluid of different-sized follicles: relationship to intra-follicular inhibin and steroid concentrations

Matrix metalloproteinases (MMPs) play very important roles in extracellular matrix (ECM) remodeling during ovarian follicular development, ovulation and atresia. The aim of the present study was to determine the content of gelatinases in follicular fluid in various sized bovine follicles. Bovine ovaries were collected from local slaughterhouse and follicular fluid from follicles of 2 to over 25 mm in diameter was collected. Gelatinase activity within the follicular fluid was analyzed by gelatin zymography. The concentration of inhibin in the follicular fluid was also measured by immunoblot analysis. The proMMP-2 and alpha-subunit (alphaN) inhibin was detected in all follicles regardless of their size. The abundance of proMMP-2 varied with follicular size, while alphaN inhibin increased significantly (P<0.01) in follicles of 10-14 and 15-20 mm in size. There was a positive and negative correlation between estradiol (E(2)) and progesterone (P(4)) concentrations with abundance of proMMP-2, respectively. Follicles of diameter over 25 mm had greater proMMP-9 activity than other follicles. These same follicles had significantly (P<0.01) lower inhibin levels than follicles of 10-14 and 15-20 mm in size. In conclusion, these results suggest a significant role of these proteases in growth and development of bovine follicle, particularly proMMP-2 and active MMP-2 activities in the follicular fluid could serve as markers of follicular health while abundance of proMMP-9 may possibly denote a follicular cyst.