Microstructure of the adhesive pad in the millipede Orthomorphella pekuensis (Polydesmida: Paradoxosomatidae)

Secondary sexual structures in millipedes have evolved to improve the efficiency with which spermatophores are transferred from males to females. Here, we demonstrate the microstructural characteristics of the sexual dimorphism in the leg adhesive pads of the millipede Orthomorphella pekuensis, using field emission scanning electron microscopy. The adult male of this millipede has developed typical adhesive pads on the legs as a secondary sexual character: these help the male hold on to the female during mating. The adhesive pads are located on the ventral surface of the tarsus in the form of numerous filamentous bristles with horizontal striation. There are approximately 300 bristles, each with an average length of approximately 60 µm, on each tarsus. Each bristle has a round socket on the surface of the tarsus and an acuminate tip. The striation appears only on the distal half of each bristle, typically.     

Dihydrofolate Reductase from Eimeria tenella: Rationalization of Chemotherapeutic Efficacy of Pyrimethamine

SYNOPSIS. Dihydrofolate reductase activity of 0.2 nmole of dihydrofolate reduced/min/mg protein was detected in crude extracts of unsporulated oocysts of Eimeria tenella. The enzyme was purified by a combination of affinity and ion-exchange chromatography. Its molecular weight was estimated as 240,000 daltons. An anticoccidial drug pyrimethamine is a potent inhibitor of the activity of E. tenella dihydrofolate reductase ( K _t = 3 nM), but it is less effective an inhibitor of dihydrofolate reductase from chicken liver. This difference may explain the in vivo therapeutic action of pyrimethamine against Coccidia.     

The family classification of the Anoplura

Fifteen families of Anoplura are recognized and defined, one with two sub-families, and a key is provided for their identification. The included genera are listed for each family, together with the relevant type-species as well as the mammalian hosts. Phylogenetic relationships between the families are discussed, and an extensive historical review and analysis of the available taxonomic characters is presented.     

A stress‐inducible sulphotransferase sulphonates salicylic acid and confers pathogen resistance in Arabidopsis

Sulphonation of small molecules by cytosolic sulphotransferases in mammals is an important process in which endogenous molecules are modified for inactivation/activation of their biological effects. Plants possess large numbers of sulphotransferase genes, but their biological functions are largely unknown. Here, we present a functional analysis of the Arabidopsis sulphotransferase AtSOT12 (At2g03760). AtSOT12 gene expression is strongly induced by salt, and osmotic stress and hormone treatments. The T‐DNA knock‐out mutant sot12 exhibited hypersensitivity to NaCl and ABA in seed germination, and to salicylic acid (SA) in seedling growth. In vitro enzyme activity assay revealed that AtSOT12 sulphonates SA, and endogenous SA levels suggested that sulphonation of SA positively regulates SA production. Upon challenging with the pathogen Pseudomonas syringae, sot12 mutant and AtSOT12 over‐expressing lines accumulate less and more SA, respectively, when compared with wild type. Consistent with the changes in SA levels, the sot12 mutant was more susceptible, while AtSOT12 over‐expressing plants are more resistant to pathogen infection. Moreover, pathogen‐induced PR gene expression in systemic leaves was significantly enhanced in AtSOT12 over‐expressing plants. The role of sulphonation of SA in SA production, mobile signalling and acquired systemic resistance is discussed.     

Low temperature and mechanical stresses differently gate aquaporins of root cortical cells of chilling-sensitive cucumber and -resistant figleaf gourd

The inhibition of the hydraulic conductivity of individual cortical cells (Lp) of young roots of cucumber and figleaf gourd by low root temperature (8 °C, LRT) was measured using a cell pressure probe. When LRT was imposed, the Lp of the two species responded differently. Water permeability of cortical cells of chilling-sensitive cucumber decreased by a factor of 10, but there was only a small effect in the chilling-resistant figleaf gourd. Mechanical stresses (pulses of cell turgor pressure) resulted in a similar inhibition for both species by a factor of 6.5. When applied at LRT, abscisic acid (ABA) partially or even completely reversed the effects of chilling and mechanical stresses of both species. At the control temperature of 22 °C, 50 µm of the aquaporin (AQP) inhibitor HgCl₂ acted on root cells of both species, although the effect on root cells of figleaf gourd was small. There was no effect of HgCl₂, when AQPs were already closed either by LRT or by mechanical stress. The effect of mechanical stress (pressure pulses) was substantially bigger than that of HgCl₂. When AQPs were closed by big pulses in the presence of 50 µm HgCl₂, they could be partially re-opened in the presence of the inhibitor by applying small pulses, suggesting that there are at least two different types of channels present, which respond differently to mechanical stress or to the heavy metal. The presence of 1 µm ABA in the root medium prevented the effects of LRT and mechanical stress, namely an increase in the half-times of water exchange (T^w_1/2 ∝ 1/Lp). In the absence of stresses at short T^w_1/2, there was no effect of ABA. It is concluded that the responsiveness of AQPs of the two species differs in the presence of LRT but not under conditions of mechanical stress. In both cases, however, ABA has an ameliorative effect. The results suggest that the presence of ABA reduces the activation energy of changes of the conformation of AQPs, when switching between open and closed states. Mechanisms of the gating of AQP activity by LRT and mechanical stresses and the possible role of the stress hormone ABA are discussed.     

Surface Coat Movements in Unfertilized Amphibian Eggs

Several features of the surface coat movements displayed by unfertilized, uncleaved amphibian eggs were examined. Those movements were examined in a variety of species, and investigated in detail in Rana eggs. Continuous exposure to a salt solution is a prerequisite for surface coat movements. Various inhibitors were tested for their capacity to inhibit those movements. The possibility was examined that the primary embryonic organizer might be localized in the area which resembles the dorsal lip of normal gastrulae.