Differential Rates of Uptake of Glucose, Fructose and Sucrose by Pea Stem Protoplasts

Protoplasts from growing regions of etiolated pea stems takeup glucose more rapidly than fructose when supplied for briefperiods at low concentrations. The uptake of the two hexosesis differentially inhibited by galactoac and by reagents thatcurtail ATP synthesis, and uptake of one hexose is not preventedby the other, even at a 100-fold excess. Sucrose uptake is muchslower than that of either hexose and is correlated with theappearance of invertase activity in the medium. Label from [¹⁴C-glc]-sucroseis taken up more rapidly than from [¹⁴C-fru]-sucrose. It isconcluded that these cells take up supplied sucrose only afterhydrolysis to hexoses, which are then absorbed by differentcarrier-mediated processes. Key words: Glucose, fructose, invertase, pea, protoplast, sucrose     

Regulators of Cell Division in Plant Tissues XIV. The Cytokinin Activities and Metabolism of 6-Acylaminopurines

Certain 6-acylaminopurines have been shown to exhibit activity in several cytokinin bioassays. The active compunds included 6-N,2′-O-dibutyryladenosine 3’:5′-cyclic monophosphate, but adenosine 3′:5′-cyclic monophosphate was inactive. The metabolites formed from [2,8-³H] 6-benzoylaminopurine by radish seedlings and excised radish cotyledons were investigated. When compared with zeatin, this amide showed considerable stability in vivo. Conversion to 6-benzylaminopurine and its riboside was not detected but slight degradation to adenine was indicated. The principal metabolite was an unidentified compund.     

Growth Response to Hormones by a New Rat Ovary Cell Line

SEVERAL endocrine cell lines established in recent years show a functional response to hormones in vitro¹ but, except for one mammary cell line², none of them exhibits the normal hormone requirement for growth in vivo. We have now isolated a rat ovarian cell line whose growth in vitro is markedly stimulated by bovine luteinizing hormone (LH-NIH-B7), a pituitary gonadotrophin and by dexamethasone, a synthetic glucocorticoid. This cell line provides the first permanent in vitro system for studying the growth stimulation of gonadal cells by hormones.     

Some Blood Sporozoans from East African Reptiles*

SYNOPSIS. Six hundred and forty-one lizards belonging to 28 species, and 29 snakes belonging to 12 species from East Africa were examined for blood sporozoans. Eight species of lizards and 4 of snakes were positive. Tissue phases were seen in some infections; no proven arthropod vectors were found. Parasites are described from previously unreported hosts; new host records, and new stages in the life histories of previously named parasites are reported. The sporozoans belong to the genera Plasmodium, Haemoproteus, Haemogregarina or Hepatozoon, and probably Pirhemocyton. Reasons are given for the inadvisability of establishing new species of some of these on the basis of blood stages alone.     

Muscle Plasticity During Sprouting and Reinnervation

SYNOPSIS. When peripheral nerves are cut, the axotomized nervesand denervated muscles undergo atrophic changes which are reversedonly when functional connections are remade in the periphery.The restored interaction completely reverses the effects ofaxotomy and denervation and leads to rematching of the sizeof the motoneuron, muscle unit force, speed and histochemicalproperties, according to the size principle. Differences inunit force and fatigue characteristics between motor unit typesare not fully restored in reinnervated muscles but do not obscuresize relationships between the motoneurons and their muscleunits. Although intact motoneurons will supply increased numbers ofmuscle fibers after partial nerve injuries, regenerating axonsappear to be limited in their ability to enlarge their muscleunits. Increased motor unit force in reinnervated slow motorunits is accounted for primarily by an increase in fiber diameter;fast motor units do not increase their mean force output. As a result of the rematching of muscle unit properties withthe size of the motoneurons that reinnervate them, motor unitproperties are appropriate for fine control of movement aftercomplete or partial nerve injuries. However, regenerating axonsdo not reinnervate their original muscle fibers and unless thefibers are injured close to the muscles, they often fail toreinnervate their original muscles. The mismatching of motorpools with inappropriate target muscles is probably the mainfactor responsible for poor recovery of motor function aftercomplete nerve injuries.     

Media and Nation Building: How the Iban Became Malaysian

Media and Nation Building: How the Iban Became Malaysian . John Postill. New York: Berghahn, 2006. 231 pp.     

Oviposition Behaviour and Reproductive Performance of Trichogramma australicum Girault (Hymenoptera: Trichogrammatidae) Reared in Artificial Diet

Biotypes of Trichogramma australicum were reared on artificial diet "A", Helicoverpa armigera (Hübner) (natural host) eggs and Sitotroga cerealella (Olivier) (factitious host) eggs. We evaluated the quality of these biotypes by comparing their oviposition behaviour and reproductive performance on H. armigera eggs. Female T. australicum reared in vitro accepted H. armigera eggs for oviposition and displayed similar behavioural components of oviposition to females reared on natural hosts. However, handling time during oviposition in H. armigera eggs by females from in vitro rearing was significantly longer than handling time of females reared on the natural host because the females needed a significantly longer time for host feeding. In vitro reared females produced significantly more progeny and parasitised more H. armigera eggs than the females reared on S. cerealella. Improvements to the artificial diet for T. australicum may reduce handling time of the in vitro reared females and increase the female population. These improvements may include changes in nutrient content and size of the artificial eggs.     

Stable-isotope and amino acid profiles of the New Zealand giant Pliocene oyster Crussostreu ingens

Mitchell, L., Curry, G.B. & Fallick, A.E. 1995 11 30: Stable-isotope and amino acid profiles of the New Zealand giant Pliocene oyster Crassostrea ingens .
Oxygen and carbon stable-isotope profiles and intracrystalline amino acid profiles (free and total) were determined for the New Zealand giant Pliocene oyster Crassostrea ingens by sampling annual growth increments along a sagittal section. These profiles reflect both ontogenetic and environmental change over the life-time of the oyster (approximately 20 years). There is a gradual increase in δ¹⁸O from the umbo towards the shell margin and a subsequent levelling-off about halfway along the shell. This pattern probably reflects a decrease in the growth rate of the oyster rather than a temperature effect. The δ¹³C profile initially increases sharply at the umbo and then gradually decreases towards the shell margin. This may be due to kinetic or metabolic effects associated with the development of a fast-growing juvenile into a slower-growing, sexually mature adult, or it may be due to the influence of ¹³C-depleted carbon derived from the oxidation of organic matter in the surrounding sediment. The amino acid profile reveals a gradual decrease in abundance from the umbo to the shell margin, indicative of a progressive increase in the relative amounts of inorganic carbonate to protein over the life of the oyster, that may also be a consequence of decreasing growth rate. Glycine and alanine are the two most common amino acids in both the free and total amino acid profiles: free (i.e. naturally hydrolysed) amino acids account for about three quarters of the total amino acids present. □ Biogeochemistiy, stable isotopes, amino acids, environment, ontogeny .     

Biological investigations on Comperia merceti (Compere), an encyrtid parasite of the cockroach Supella longipalpa (Serville)*

An account is given of the behaviour, host specificity and potential as a biological control agent of Comperia merceti, a hymenopterous parasite of cockroach oothecae.