Histone modification and signalling cascade of the dormancy‐associated MADS‐box gene,PpMADS13‐1, in Japanese pear (Pyrus pyrifolia) during endodormancy

Dormancy‐associated MADS‐box (DAM) genes play an important role in endodormancy phase transition. We investigated histone modification in the DAM homolog (PpMADS13‐1) from Japanese pear, via chromatin immunoprecipitation–quantitative PCR, to understand the mechanism behind the reduced expression of the PpMADS13‐1 gene towards endodormancy release. Our results indicated that the reduction in the active histone mark by trimethylation of the histone H3 tail at lysine 4 contributed to the reduction of PpMADS13‐1 expression towards endodormancy release. In contrast, the inactive histone mark by trimethylation of the histone H3 tail at lysine 27 in PpMADS13‐1 locus was quite low, and these levels were more similar to a negative control [normal mouse immunoglobulin G (IgG)] than to a positive control (AGAMOUS) in endodormancy phase transition. The loss of histone variant H2A.Z also coincided with the down‐regulation of PpMADS13‐1. Subsequently, we investigated the PpMADS13‐1 signalling cascade and found that PpCBF2, a pear C‐repeated binding factor, regulated PpMADS13‐1 expression via interaction of PpCBF2 with the 5′‐upstream region of PpMADS13‐1 by transient reporter assay. Furthermore, transient reporter assay confirmed no interaction between the PpMADS13‐1 protein and the pear FLOWERING LOCUS T genes. Taken together, our results enhance understanding of the molecular mechanisms underlying endodormancy phase transition in Japanese pear.     

The Occurrence and Ape-to-Ape Transmission of the Entodiniomorphid Ciliate Troglodytella abrassarti in Captive Gorillas

ABSTRACT. Entodiniomorphid ciliates are often present in the colons of wild apes. In captive apes the infection tends to gradually disappear, with the exception of Troglodytella abrassarti . We used fecal examinations to screen the gorillas ( Gorilla gorilla gorilla ) in European (Czech Republic, UK) and Australian Zoos to explore the ape-to-ape transmission pattern of T. abrassarti . Gorillas from two out of three European Zoos were positive for T. abrassarti , while gorillas from the Australian Zoo were negative. We documented a horizontal transmission of T. abrassarti to a non-infected adult gorilla introduced into a Troglodytella -positive group in the Prague Zoo and traced the origin of the ciliate infection to the Paignton Zoo (UK) using serial fecal examinations. During this study, two infant gorillas born in the Prague Zoo (CZ) first became positive for T. abrassarti at the age of 9 mo. Ciliate morphology and the sequencing of the small subunit rRNA gene and the internal transcribed spacer rDNA spacer region revealed that T. abrassarti affects both captive gorillas and chimpanzees. We conclude that zoo transport plays a major role in the distribution of T. abrassarti among captive gorillas.     

Glycine decarboxylase and serine formation in spinach leaf mitochondrial preparation with reference to photorespiration

Glycine decarboxylation and serine synthesis were investigatedto account for photorespiratory CO₂ evolution in higher plants.Glycine decarboxylase in leaf mitochondria was found to splitglycine into CO₂, NH₃ and a C₁ unit. Free glyoxylic acid wasnot involved in this process as an intermediate. Serine synthesiswas closely related to decarboxylation of glycine. We inferredthat serine is formed from two molecules of glycine by the combinedaction of glcine decarboxylase and serine hydroxymethyltransferase.Glycine decarboxylation and serine synthesis were stimulatedby NAD, PALP and THFA, and were inhibited by detergents, lipase,sonication, mechanical treatment, thyroxine and thiol compounds,suggesting the importance of structural intactness of the mitochondrialmembrane system. Glycine decarboxylase was present in intacttissues in quantities consistent with glycolate production duringphotosynthesis. We concluded that glycine decarboxylase in mitochondriais principally responsible for CO₂ evolution in photorespiration.A control mechanism of photorespiration is discussed based onthe stimulation of glycine decarboxylase by NAD and on inhibitionby NADH. ¹ A part of this work was presented at the Annual Meeting (April,1969) of the Japanese Society of Plant Physiologists, Kanazawa,and at the annual Meeting (April, 1970) of the Japanese AgricultualChemical Society, Fukuoka. (Received August 3, 1970; )     

Isotricha jalaludinii N. Sp. Found from the Rumen of Lesser Mouse Deer, Tragulus javanicus, in Malaysia

Isotricha jalaludinii n. sp. found in the rumen of lesser mouse deer, Tragulus javanicus, in Malaysia was described and illustrated. This new species is characterized by the location and direction of the vestibulum, shape of the macronucleus, and absence of a dent at the vestibular opening. The presence of single peculiar isotrichid species in the rumen of mouse deer, which is recognized as one of the most primitive ruminants, suggests that the isotrichid ciliates similar to I. jalaludinii and Isotricha intestinalis were established at a fairly early period during the evolution of ruminants.     

Host‐searching responses to herbivory‐associated chemical information and patch use depend on mating status of female solitary parasitoid wasps

1. In a tritrophic interaction system consisting of plants, herbivores, and their parasitoids, chemicals released from plants after herbivory are known to play important roles for many female parasitoids to find their hosts efficiently. On the plant side, chemical information associated with herbivory can act as an indirect defence by attracting the natural enemies of the host herbivores. 2. However, mated and virgin females of haplodiploid parasitoids might not necessarily respond to such chemical cues in the same way. Since virgin females can produce only sons, they might refrain from searching for hosts to invest eggs until copulation, in order to produce both sexes. 3. Here, we investigated differential host‐searching behaviours shown by mated and virgin females in the solitary parasitoid wasp, Cotesia vestalis, in response to herbivory‐associated chemical information from cruciferous plants infested by their host larvae, Plutella xylostella. 4. Mated females showed a significantly higher flight preference for host‐infested plants over intact plants, while no preference was observed with virgin females. Mated females also showed more intensive antennal searching and ovipositor probing behaviours to leaf squares with wounds caused by hosts than did virgin females. Furthermore, mated females stayed longer in host patches with higher parasitism rates than virgin females. 5. These results indicate that mating status of C. vestalis females clearly influences their host‐searching behaviour in response to herbivory‐associated chemical information and patch exploitation. Female parasitoids seem to forage for hosts depending on their own physiological condition in a tritrophic system.     

Effects of nitrogen nutrition on the relationships between the levels of rbcS and rbcL mRNAs and the amount of ribulose 1·5-bisphosphate carboxylase/oxygenase synthesized in the eighth leaves of rice from emergence through senescence

Soon after the emergence of the eighth leaf blades, rice plants were grown with two (1 and 4 mm ) levels of nitrogen (N) supply, and the relationships between the levels of rbcS and rbcL mRNAs, the amount of ribulose 1·5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) synthesized and the N influx were examined in the eighth leaf blades from emergence through senescence. The levels of both rbcS and rbcL mRNAs, the amount of Rubisco synthesized and the N influx were greater for the 4 mm N treatment than for the 1 mm N treatment throughout the experiment. The amount of Rubisco synthesized was well correlated with the levels of both mRNAs during leaf expansion, but not after the completion of leaf expansion in both N treatments. The ratio of the amount of Rubisco synthesized to the levels of both mRNAs dramatically declined after full expansion. On the other hand, the amount of Rubisco synthesized was well correlated with the N influx in both N treatments. These results indicate that the N influx, namely, N availability, rather than the levels of rbcS and rbcL mRNAs, is more closely related to the amount of Rubisco synthesized in the leaf blade of rice throughout the lifespan of a leaf.     

A Specific Response to Toxic Cadmium Levels in Red Kidney Bean Embryos

Cadmium salts are highly toxic to excised embryos of Phaseolus vulgaris cv. Red Kidney, inhibiting growth at concentrations in excess of 3 mg/L Inhibition is accompanied by specific toxic responses, namely inhibition of greening and induction of acute curvature in the embryonic axis. Comparisons among some 24 elements at 10 mg/l for cadmium-like effects showed silver to affect curvature, but not greening, while cobalt and nickel were the converse.     

Ciliate Protozoa in the Rumen of Kenyan Zebu Cattle,Bos taurus indicus,with the Description of Four New Species1

ABSTRACT. The composition of the fauna of rumen ciliates in zebu cattle in Kenya was surveyed and 13 genera containing 51 species with 19 formae were identified. Four new species were recognized, then described as Diplodinium africanum n. sp., Diplodinium nanum n. sp., Eudiplodinium kenyensis n. sp., and Ostracodinium iwawoi n. sp. In addition, Buetschlia triciliata and Ostracodinium stokyi were found for the second and third times and described as Hsiungia triciliata n. comb. and Enoploplastron stokyi n. stat., with two formae, respectively. The species composition was similar to that of Indian zebu but several species were considered to originate from African native ruminants. In the percentage composition of genera, the numbers of Entodinium, which normally predominate in rumens in other areas, were very low.     

Scanning Electron Microscopy of the Adoral Ciliary Zone of Entodinium Stein (Ciliophora,Entodiniomorphida)1

The adoral ciliary zone of the rumen ciliates, Entodinium spp., was observed topographically in the SEM. The upper side of the anterior end of the body was indented by the vestibulum, which had cilia arranged on its right wall and ribs along the left wall. The adoral ciliary zone could be divided into at least two arrangements. The outer ciliary zone had many membranelle-like structures, which consisted of cilia arranged radially from the body axis. Each membranelle-like structure consisted of two rows of about eight cilia each lining up in a single file. It was, however, different from a typical membranelle, because its cilia were connected with the vestibular cilia and were arranged not spirally but on a plane. These cilia extended toward the outside because of the projecting cytoplasm from which they originated. In contrast, the cilia of the inner ciliary zone were aggregated to form relatively unsystematic bundles. Since the vestibular opening was slanted on the upper side of the body, the ciliary bundles were thick on the lower side and sparse on the upper side of the body. Neither outer nor inner ciliary zones completely surrounded the vestibular opening. The ciliature started from the left side of the vestibular opening, encircled the lower side of the body, and entered the vestibulum from its right side. The functions of these two types of ciliary arrangements are discussed.