Geographical variation in mandible morphologies specialised for collembolan predation depend on prey size in the ant Strumigenys lewisi

1. Ants in the genus Strumigenys are predator ants that feed on tiny soil arthropods. The mandibles are modified into high‐speed traps to capture swift collembolan prey. The peculiar mandible morphologies of these ants have evolved depending on characteristics of the prey. Specifically, the evolution of mandible size and shape may be directly driven by prey size. 2. In the present study, the intraspecific variation of the morphological traits of Strumigenys lewisi populations were observed in central Japan. The relationships between the morphological variations and the prey body size were analysed. 3. In workers and queens, three morphological traits, head width, mandible length, and mandible width were significantly different among the multiple sites. Specifically, the mandible length was shorter in southwestern Japan than in other sampling locations. The ancova model revealed that the allometry of the mandible length to the head width was different among the sites. 4. As predicted, the mandible length was positively correlated with the average body size of collembolans in the Entomobryidae family. Furthermore, multiple regression analysis showed that the variation of the mandible length was affected by environmental factors represented as location information. However, the effect of collembolan body size was more effective at predicting mandible length. The study suggests that the geographical variation of mandible morphologies in S. lewisi has been selected by predator–prey interactions with collembolans.     

Effects of Organic Solvents on the Coupling Between ATP Hydrolysis and Sliding of Microtubules in Axonemes from Chlamydomonas Flagella

ABSTRACT. The effects of organic solvents on the ATPase activity and the sliding disintegration of axonemes from Chlamydomonas were investigated. The axonemal ATPase was markedly activated by methanol accompanying with marked inhibition of the sliding disintegration of axonemes. On the contrary, glycerol inhibited the ATPase activity without serious inhibition of the sliding disintegration. As far as the axonemes are not irreversibly denatured by extremely high concentration of solvents, the effects of solvents both on the ATPase and the ability of sliding are reversible. Therefore, the inhibition of sliding accompanied by the activation of ATPase is probably due to an inability to couple the hydrolysis of ATP to sliding between dynein and microtubule in the presence of methanol. The axonemal ATPase was less sensitive to vanadate inhibition after exposure to methanol. This indicates that methanol makes the dyneinADP.Pi complex unstable and increases product release. On the other hand, glycerol and ethylene glycol seem to stabilize the force generation responsible for the sliding through stabilizing the dynein.ADP.Pi complex.     

Metabolism of Round Spermatids: A Possible Regulation of Hexose Transport

Round spermatids (steps 1–8) were isolated from rat testes and glucose transport into the cells was examined. The exposure of spermatids to glucose resulted in an extremely low level of ATP. In contrast, the level of ATP remained constant in the presence of pyruvate. Transport of a glucose analogue, 2-deoxy-D-[³H]glucose ([³H]dGlc) into spermatids was correlated with intracellular levels of ATP and was much greater in cells with higher rather than lower levels of ATP. [³H]dGlc transport into spermatids with low levels of ATP was partially reversed when the cells were incubated with pyruvate. Inhibition of [³H]dGlc transport was exerted on Vmax and not on Km. Moreover, glucose acted as a competitive inhibitor of [³H]dGlc uptake (Km increased; Vmax unaltered). These results suggest that glucose transport into spermatids is active in vitro and probably regulated by the intracellular level of ATP.     

Reactivity of a Monoclonal Antibody Raised against Human Leukemic Cells to Embryonic and Adult Tissues of the Mouse and Teratocarcinomas

C-9-1, a monoclonal IgM antibody raised against human null cell acute lymphocytic leukemia cells reacted with restricted regions of embryonic and adult tissues of the mouse. The antigen positive sites in the embryos included embryonic ectoderm, visceral endoderm, trophoblastic cells invading the maternal decidua of 5∼7-day embryos, primordial germ cells of 10∼12-day embryos, epithelium of nasal chamber, the bronchus, Mullerian duct, epididymis and bladder of 12∼17-day embryos. In the adult mice, C-9-1 antigen was detected in renal tubules, a part of stomach, bladder, endometrium and epididymal sperm. Embryonal carcinoma cells, but not endodermal cells of teratocarcinoma expressed the antigen. Thus, C-9-1 antigen showed distribution similar to SSEA-1. However, C-9-1 antigen was not detected in preimplantation embryos, nor in oviduct, both of which are positive for SSEA-1.     

Alicyclic acid metabolism in plants 3. Fate of 14C-shikimate and 14C-quinate in mung bean plants

Young mung bean plants (Phaseolus mungo) were exposed to ¹⁴C-shikimateor ¹⁴C-quinate in the light. After 8 or 23.5 hr of incubationat 25°C, radioactivities in free and bound amino acids,organic acids, soluble and insoluble carbohydrates, ether-solublefraction and lignin were determined. Shikimic and quinic acidswere separated by the combined use of paper-chromatography andcolumn chromatography. Specific activity of formed quinate orshikimate was only slightly lower than that of fed shikimateor quinate. Specific activities of phenylalanine, tyrosine andbound tryptophan were high as compared with those of non-aromaticamino acids. Discussion is focused upon the interconversionbetween shikimate and quinate, and their roles in the biosynthesisof aromatic amino acids. (Received November 15, 1968; )     

Structure of Major Surface Determinants and DNA Diagnosis of Pneumocystis carinii

Pneumocystis carinii is a pathogen which, causes fatal pneumonia in patients with the acquired immune deficiency syndrome (AIDS). To facilitate the basic study of P. carinii , we have analyzed its major surface proteins by both immunochemical and biochemical methods. The major protein components of both cysts and trophozoites are a group of proteins called "P115" with apparent masses of 105–120 kd. It includes 6 isoelcclric variants. A monoclonal antibody raised against cysts recognizes all 6 variants and reacts with epitopes located in the cell wall indicating that P115 is an immunorcactive surface component. The isoelectric variants contain identical or closely related protein components and they are mannose-rich glycoproteins. The isoelectric variation may be due primarily to differences in glycosylation. The majority of sera from humans with diagnosed pneumocystosis that were tested reacted strongly with the P115 proteins. To develop probes for DNA diagnosis and to facilitate molecular studies, a genomic DNA library of P. carinii has been constructed. Some of these clones were used for DNA hybridization analysis of rat and human lungs.     

Synergistic Inhibition of Fructose 1,6-Bisphosphatase by Fructose 2,6-Bisphosphate and Adenosine Monophosphate in Round Spermatids of Rats

The effects of adenosine monophosphate (AMP) and fructose 2, 6-bisphosphate (fruc-2, 6-P₂) on the key-enzyme of gluconeogenesis, fructose 1, 6-bisphosphatase (fruc-P₂ase; D-fructose 1, 6-bisphosphate 1-phosphohydrolase, EC 3.1.3.11) in spermatid extract from rat testes were studied. The fruc-P₂ase activity in the spermatids of rats was suppressed by AMP and fruc-2, 6-P₂. The inhibition of fruc-2, 6-P₂ was much stronger at low than at high substrate concentrations, and enhanced synergistically with AMP. The substrate saturation curve was changed by fruc-2, 6-P₂ hyperbolic to sigmoidal. Furthermore, the concentration of AMP that decreased the activity to 50% was much lower in the presence than in the absence of fruc-2, 6-P₂. These results indicate the possibility that gluconeogenesis in spermatids of rats is controlled by AMP and fruc-2, 6-P₂.     

Multiple Forms of Acid Phosphatase in Cotyledons of Vigna mungo Seedlings

Acid phosphatase from cotyledons of dark-grown Vigna mungo seedlingswas separated into four forms (la, Ib, Ha and lib) by ion-exchangercolumn chromatographies. Each form of the acid phosphatase wascharacterized for its pH dependency, substrate specificity,thermal stability, activation energy, approximate molecularweight, and the effect of metal ions and other substances onits activity. Each form of the enzyme exhibited high activitytowards ATP and ADP relative to their activity towards p-nitrophenylphosphate,but showed very low activity towards phytate, a major organicphosphate reserve in cotyledons. Among the four forms, lib wasmost distinguishable by its low molecular weight and the thermalenhancement of activity.     

2. Alicyclic acid metabolism in plants Enzymes related to the shikimate pathway in developing mung bean seedlings

A study was made of chages in the activities of enzymes relatedto the biosynthesis of aromatic compounds in etiolated mungbean seedlings during their growth. Shikimate: NADP oxidoreductaseactivity in the root-shoot axes increased rapidly to attainits highest activity the 4th day after sowing, and remainedat that level over the experimental period of 7 days. 5-Dehydroquinatehydro-lyase activity continuously increased for at least 7 days.In the cotyledons, a gradual decrease in the activities of theseenzymes occurred. Phenylalanine ammonia-lyase activity in root-shootaxes gradually increased showing a maximum on the 6th day. Thehighest specific activity, on a protein basis, of this enzymewas seen in the initial stage of growth. In the cotyledons,a rise in total activity appeared on the 2nd day. Tyrosine ammonia-lyaseactivity was very low as compared with phenylalanine ammonia-lyase.The enzyme activities of light-germinated seedlings were comparedto those of dark-germinated seedlings on the 7th day. Lighthad practically no significant effect on the appearance of shikimate:NADP oxidoreductase and 5-dehydroquinate hydro-lyase activities.On the other hand, a marked effect from the light on the riseof phenylalanine ammonia-lyase and tyrosine ammonia-lyase activitieswas found, especially in the epicotyl-plumules. The results are discussed with respect to the metabolism ofalicyclic acids such as shikimic acid in the developing mungbean seedlings. ¹This work was partly supported by a grant-in-aid from the Ministryof Education.