The phylogenetic basis of sexual size dimorphism in orb-weaving spiders (Araneae,Orbiculariae)

Extreme sexual body size dimorphism (SSD), in which males are only a small fraction of the size of the females, occurs only in a few, mostly marine, taxonomic groups. Spiders are the only terrestrial group in which small males are relatively common, particularly among orb-weavers (especially in the families Tetragnathidae and Araneidae) and crab spiders (Thomisidae). We used a taxonomic sample of 80 genera to study the phylogenetic patterns (origins and reversals) of SSD in orb-weaving spiders (Orbiculariae). We collected and compiled male and female size data (adult body length) for 536 species. Size data were treated as a continuous character, and ancestral sizes, for males and females separately, were reconstructed by using Wagner parsimony on a cladogram for the 80 genera used in this study. Of these 80 genera, 24 were female-biased dimorphic (twice or more the body length of the male); the remaining 56 genera were monomorphic. Under parsimony only four independent origins of dimorphism are required: in the theridiid genus Tidarren, in the distal nephilines, in the "argiopoid clade," and in the araneid genus Kaira. Dimorphism has reversed to monomorphism at least seven times, all of them within the large "argiopoid clade." The four independent origins of dimorphism represent two separate instances of an increase in female size coupled with a decrease of male size (involving only two genera), and two separate instances of an increase in female size with male size either remaining the same or increasing, but not as much as females (involving 30 genera). In orb-weaving spiders, far more taxa are sexually dimorphic as a result of female size increase (22 genera) than as a result of male size decrease (two genera). SSD in orb-weaving spiders encompasses several independent evolutionary histories that together suggest a variety of evolutionary pathways. This multiplicity strongly refutes all efforts thus far to find a general explanation for either the origin or maintenance (or both) of SSD, because the different pathways very likely will require distinctly different, possibly unique, explanations. Each pattern must be understood historically before its origin and maintenance can be explained in ecological and evolutionary terms. The most frequently cited example of male dwarfism in spiders, the golden orb-weaving spider genus Nephila (Tetragnathidae), is in fact a case of female giantism, not male dwarfism.     

Accumulation of amino acids in muscle of perfused rat heart. Effect of insulin in the presence of puromycin

1. Rat heart was perfused with a mixture of amino acids and other ninhydrin-positive substances in the same concentrations as they are found in plasma, and with or without sufficient puromycin to suppress protein synthesis all but completely. 2. In the presence of puromycin, but not in its absence, insulin increased the concentrations of most of the individual amino acids in the intracellular water of heart. 3. The results accord with the conclusion that insulin increases the entry of most, if not all, amino acids into muscle.     

Effect of trifluoperazine, compound 48/80, TMB-8 and verapamil on ionophore A23187 induced calcium transients in human red cells

A transient increase of cellular calcium was induced by addition of the divalent cation ionophore A23187 to human red cells in the absence or presence of drugs. The peak height of the calcium transient was increased about five times at pH 6.9 and up to eighteen times at pH 7.4 by trifluoperazine (0.30 mM), and two to three times at pH 6.9 by compound 48/80 (0.89 mg/ml), 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8, 2.13 mM) and verapamil (1.81 mM). The time-dependent changes of cellular calcium were analysed by the aid of a pump-leak model based partly on the calcium dependent parameters obtained from calcium ATPase experiments, partly on the A23187 induced calcium fluxes determined in experiments with ATP depleted cells. The transient increase of cellular calcium induced within few minutes after the addition of ionophore A23187 could be explained satisfactorily by the model both in the absence and presence of the four drugs, whereas the final level of cellular calcium in the drug experiments was more difficult to predict from the pump-leak model. Comparison of experimental and model calcium transients suggested that trifluoperazine and TMB-8 affected both pump and leak, whereas compound 48/80, probably due to low membrane-permeability, mainly affected the leak and verapamil affected the pump only.     

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Reversible shift between two states of Ca2+-ATPase in human erythrocytes mediated by Ca2+ and a membrane-bound activator.

The (Ca2+ + Mg2+)-dependent ATPase (ATP phosphohydrolase, EC 3.6.1.3) from human erythrocytes occurred in two different states, A-state and B-state, depending on the membrane preparation. The A-state showed low maximum activity (V) and the Ca2+ activation was characterized by a Hill coefficient, nH, of about 1 and a Michaelis constant, KCa, about 30 micron. The B-state showed high V, a nH above 1, which indicates positive cooperativity of Ca2+ activation, and KCa of about 1 micron. With varying ATP concentrations, both the A-state and B-state showed negative cooperativity and slightly different values of Km. The B-state was shifted to A-state when the membranes were exposed to low Ca2+ concentration. The shift reached 50% at approx. 0.5 micron Ca2+. At the low Ca2+ concentrations an activator was released from the membranes. The A-state was shifted to the B-state when the membranes were exposed to Ca2+ in the presence of the activator. The shift reached 50% at about 30 micron Ca2+. The recovery of high V was time dependent and lasted several minutes. Increasing concentrations of Ca2+ and activator accelerated the recovery. It is suggested that the A-state and the B-state correspond to enzyme free of activator and enzyme associated with activator, respectively. Furthermore, the two states may respresent a resting and an active state, respectively, of the calcium pump.