Growth and development of winter tick, Dermacentor albipictus, on moose, Alces alces

Moose, Alces alces, were infested with 21,000 or 42,000 larval Dermacentor albipictus at the end of September. Larvae grew rapidly and molted to the nymphal stage 10-22 days after infestation. The nymphal stage lasted approximately 3 mo until mid-January and was characterized by a diapause. The diapause is likely an adaptation to survival in cold climates. Nymphs started engorging in January and adults were seen with increasing abundance from mid-January to March and April. The minimum parasitic period was 175 days. Growth of larvae and nymphs was similar on moose given different numbers of larvae and was generally similar between a moose infested in November and moose infested earlier. Dimensions and stages of development throughout the parasitic phase are given. Game enforcement officers are encouraged to use these data for determination of season of death of moose.     

High level of divergence of male-reproductive-tract proteins, between Drosophila melanogaster and its sibling species, D. simulans

We compared male-reproductive-tract polypeptides of Drosophila melanogaster and D. simulans by using two-dimensional gel electrophoresis. Approximately 64% of male-reproductive-tract polypeptides were identical between two randomly chosen isofemale lines from these two species, compared with 83% identity for third-instar imaginal wing-disc polypeptides. Qualitatively similar differences were found between reproductive tracts and imaginal discs when D. sechellia was compared with D. melanogaster and with D. simulans. When genic polymorphism was taken into account, approximately 10% of male- reproductive-tract polypeptides were apparently fixed for different alleles between D. melanogaster and D. simulans; this proportion is the same as that found for soluble enzymes by one-dimensional gel electrophoresis. Strikingly, approximately 20% of male-reproductive- tract polypeptides of either D. melanogaster or D. simulans had no detectable homologue in the other species. We propose that proteins of the Drosophila male reproductive tract may have diverged more extensively between species than have other types of proteins and that much of this divergence may involve large changes in levels of polypeptide expression.      

Kinetic and spectroscopic studies of haemoglobin and myoglobin from Urechis caupo. Distal residue effects.

Seven components of the tetrameric haemoglobin (Hbu) from Urechis caupo were separated by preparative isoelectric focusing and characterized by their absorption spectra and pI values. The helix content and Soret delta epsilon values are reported for several of the components. Temperature-jump O2-binding kinetics of the major components of Hbu show biphasic behaviour, with the majority species having kon = 1.57 x 10(9) mol-1.s-1 and koff = 3.32 x 10(4) s-1. The Fourier-transform i.r. spectrum of pooled Hbu(II)-CO displays a stretching frequency of 1942 cm-1. E.s.r. of Hbu(II)-NO demonstrates evidence of proximal strain similar to that encountered in T-state human haemoglobin. CO-driven reduction of U. caupo methaemoglobin, Hbu(III) and U. caupo metmyoglobin [Mbu(III)] shows much higher rates relative to haemoglobins and myoglobins known to possess a distal histidine residue. Nitrosyl auto-reduction kinetics of Hbu(III)-NO and Mbu(III)-NO are examined. The equilibrium binding constants of several ligands are reported for both Hbu and Mbu, and together with the above kinetic data suggest differences in haem pocket environments between Hbu and Mbu. Reaction of Hbu with 2-chloromercuri-4,6-dinitrophenol demonstrates the presence of one reactive thiol group per globin chain. lambda max. values and the respective molar absorption coefficients for selected ligand-bound states are reported for the major component of Hbu and for Mbu. The majority haem orientation in U. caupo haemoglobin is identical with that of human haemoglobin.     

Microelectrode studies of the active Na transport pathway of frog skin

When the outer surface of short-circuited frog skin was penetrated with microelectrodes, stable negative potentials that averaged near -100 mV were recorded consistently, confirming the results of Nagel (W. Nagel. 1975. Abstracts of the 5th International Biophysics Congress, Copenhagen. P-147.). The appearance of these stable potentials, V(O), concurrent with the observations that (a) a high resistance outer barrier R(O) accounting for approximately 75 percent or more of the transcellular resistance of control skins had been penetrated and that (b) 10(-5) M amiloride and reduced [Na] outside caused the values of V(O) to increase towards means value near -130 mV while the values of percent R(O) increased to more than 90 percent. It was of relationships were the same as the values of E(1) observed in studies of the current-voltage relationships were the same as the values of E’(1) defined as the values of voltage at the inner barrier when the V(O) of the outer barrier was reduced to zero by voltage clamping of the skins. Accordingly, these data are interpreted to mean that the values of E(1), approximately 130 mV, represent the E(Na) of the sodium pump at the inner barrier. 2,4-DNP was observed to decrease the values of transepithelial voltage less than E(1) the V(O) was negative. These data can be interpreted with a simple electrical equivalent circuit of the active sodium transport pathway of the frog skin that includes the idea that the outer membrane behaves as an electrical rectifier for ion transport.