Contributions to the life-history of Rhodochorton floridulum (Dillw.) Näg

The morphology of the tetrasporophyte of Rhodochorton floridulum (Dillwyn) Näg. has been examined in an attempt to discover the nature of the factors responsible for the sand-binding powers of the species. It has been found that there are several types of specialised laterals which interweave with the erect filaments to produce a complex, three-dimensional network in the free spaces of which sand particles are bound.     

The role of two plant-derived volatiles in the foraging movement of 1st instar Helicoverpa armigera (Hübner): time to stop and smell the flowers

Positive phototaxis and negative geotaxis are behaviours that 1st instar Helicoverpa armigera use to direct their foraging movement upward towards nutritious new plant growth and reproductive structures. Odours emitted by fruits or seeds can attract larvae directly via chemotaxis. In this study we clarify the effect of leaf and flower odours on foraging 1st instar H. armigera. Using a Y-tube olfactometer we tested for chemotaxis towards two plant volatiles and found larvae were not attracted. Bioassays for phototaxis towards UV, blue, green and white light showed that a green leaf volatile ((Z)-3-hexenyl acetate) and a flower volatile (phenylacetaldehyde) reduced larval phototaxis towards blue light. Feeding on a host plant reduced phototaxis towards blue and green light. We concluded that the upward movement of 1st instars on plants is largely due to phototaxis towards the blue wavelengths of skylight. Plant attributes such as volatile chemicals affect the expression of phototaxis and therefore, indirectly influence larval movement to locate food resources. Handling Editor: Anna-Karin Borg-Karlson     

Numerical and behavioural responses of migrant passerines to experimental manipulation of resident tits (Parus spp.): heterospecific attraction in northern breeding bird communites?

Summary We studied experimentally interspecific competition among foliage-gleaning passerine birds by manipulating the density of resident tits. In 1988 tit density was experimentally increased on three small islands in a central Finnish lake, and decreased on three other islands by tit removal. In order to avoid the effects of between-island differences in habitat quality, the role of the islands was reversed when the experiment was repeated in the following year. Censuses and observations on foraging and feeding behaviour were conducted to assess the numerical and behavioural responses of migrant conguilders (mainly chaffinches and willow warblers) with respect to the manipulated abundance of the tits. We also measured whether variation in food consumption of tits affected the frequency with which the migrants found food by calculating average intervals between successful prey captures, time lags to prey-capture and giving-up times. Our results indicate that interspecific competition is of minor importance in structuring breeding bird assemblages and species feeding ecologies on the study islands. No consistent difference in foraging or feeding niches of chaffinches and willow warblers was found between low and high tit density conditions. Niche overlap analysis showed no avoidance by chaffinches and willow warblers of the microhabitats which tits used. Tit abundance had no significant effect on feeding success or behaviour. Experimentally increased abundance of resident birds was associated with increased abundance of breeding migrants, however. This pattern was found not only in the foliage gleaning guild but also with all passerine birds, indicating that food was not an important contributor to this pattern. We elaborate a hypothesis suggesting heterospecific attraction in northern breeding bird assemblages. Habitat generalist migrants may use the presence of residents as an indicator of safe and/or productive breeding sites in northern unpredictable circumstances.     

Somatic embryogenesis and plant recovery from mature tissues of olive cultivars (Olea europaea L.) “canino” and “moraiolo”

Summary A cyclic system of somatic embryogenesis from mature tissues of olive (Olea europaea L.) and subsequent plant recovery were developed. The primary embryos originated from morphogenetic masses derived from petioles of shoots regenerated from tissues of two micropropagated cultivars: Canino and Moraiolo. The rejuvenation acquired by the shoots by regeneration, directly from petiole tissues or indirectly from petiole callus, seems to be essential for the subsequent somatic embryogenesis induction. Cyclic embryogenesis, both from normal embryos or teratoma, was obtained on modified olive medium (OMe) plus 0.5 M; 6dimethylaminopurine, 0.44 M 6-benzylaminopurine, 0.25 M 3-indolebutyric acid and 0.42 mM cefotaxime. The production of normal embryos was higher, faster and often more clustered on a filter paper liquid medium or on a media solidified with phytagel than with agar. The capacity to produce continuous cycles of successive embryos has been maintained for over two years only in the dark, since the light inhibited embryo induction. The embryogenetic capacity was qualitatively and quantitatively enhanced by adding 0.42 mM cefotaxime. Mature embryos germinated easily by increasing the amount of liquid medium with shake culture. Although the majority of embryos appeared vitrified when transplanted to Jiffy-7 pots, they subsequently grew normally and were similar to those derived from nonvitrified embryos. The plantlets obtained from somatic embryos appeared to be morphologically similar to those produced from axillary buds.Abbreviations IBA 3-indolebutyric acid - BAP 6benzylaminopurine - TDZ thidiazuron - 2iP 6dimethylaminopurine - NAA 1-naphthaleneacetic acid - MS Murashige and Skoog (1962) - BN Bourgin and Nitsch (1967) - OM olive medium (Rugini 1984) - OMs modified olive medium - (OM) for shoot organogenesis - OMe modified olive medium - (OM) for somatic embryogenesis     

Behavioral and electrophysiological responses of the parasitic wasp Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae) to Ceratitis capitata-induced fruit volatiles

Psyttalia concolor (Szépligeti) is a koinobiont larval-pupal endoparasitoid of many Tephritidae of great economic importance, such as the medfly, Ceratitis capitata (Wiedemann). In several species of parasitoids it has been demonstrated that the mated females are strongly attracted by specific volatiles from insect-damaged plants. Yet the role of olfactory cues deriving from C. capitata-infested fruits on the female’s decision during the P. concolor host location was poorly investigated. In the present study, the responses of P. concolor females to either healthy or C. capitata-infested fruits was studied through behavioral assays. Volatiles emitted by healthy and infested fruits were SPME-sampled and analyzed by gas chromatography–mass spectrometry (GC–MS). The attractiveness of the identified volatiles was assessed and their electrophysiological activity was analyzed through gas-chromatography coupled with electroantennography (GC-EAD). P. concolor preferred infested peaches and apples over healthy ones, either when visual and olfactory or only olfactory cues were given. Nine compounds were found as exclusive of infested peaches, with respect to healthy ones, and seven of them evoked electrophysiological responses. In apples only quantitative changes in volatile emissions were observed after the medfly infestation. The emissions of 1-butyl butylate, 1-hexyl acetate and 1-butyl esanoate increased in infested apples, whereas 1-hexyl (E)-2-methyl butenoate decreased significantly. Among apple volatiles, 1-butyl butylate, 2-methyl-1-butyl acetate, 1-hexyl acetate, 2-methyl-1-butyl 2-methylbutanoate, 1-butyl hexanoate and 1-hexyl (E)-2-methyl butenoate elicited responses in female antennae. Synthetic blends reproducing the odors emitted by infested peaches and apples elicited strong attraction towards P. concolor females. For both fruits, the blend attractiveness was mainly due to some specific electrophysiological active chemicals: ethyl octanoate, decanal and 4-decanolide for peach, and 1-butyl butylate and 1-butyl hexanoate for apple. The responses induced by the identified fruit volatiles to P. concolor females allow us to suppose that they play a role as short-range attractants during host location.     

Contractile responses of longitudinal and circular smooth muscle of the canine stomach to prostaglandins E and F2α

Muscle strips were excised from the circular and longitudinal layers of the fundus, corpus and antrum, and from the inner portion of the pyloric ring. In general prostaglandin(PG)F₂α as well as PGE₁ and PGE₂ stimulated the longitudinal muscle. However, there were remarkable regional differences. The sensitivity to PGs was greatest in the fundus and corpus (threshold near 10⁻¹⁰ mol/1) and only weak in antrum (threshold 5·10⁻⁸ to 10⁻⁷ mol/1). In longitudinal antrum strips acetylcholine induced a combined phasic-tonic response, whereas PGs produced purely phasic responses. The effects of PGF_2α and PGE on the circular layer were complex. PGF_2α produced excitatory responses in circular fundus and corpus similar to those in the longitudinal layer of the same regions. PGE produced dual responses in circular fundus (excitation at low concentration and strong inhibition at concentration of 10⁻⁷ mol/1). In circular corpus PGE induced pure inhibition (threshold near 10⁻⁹ mol/1). In circular antrum and inner pylorus both PGE and PGF_2α produced inhibition of the phasic activity (threshold 10⁻⁸ to 10⁻⁷ for antrum and 10⁻⁹ mol/1 for inner pylorus). These effects of PGs appeared in the presence of adrenergic and cholinergic blocking agents as well as of tetrodotoxin and were therefore, direct effects on smooth muscle. Indomethacin (10⁻⁷–10⁻⁶ mol/1) suppressed spontaneous tone of the fundus and corpus and increased phasic activity of inner pylorus. This indicates that endogenous PG synthesis may be involved in the control of spontaneous activity in gastric muscle.     

Effects of the planting density on water relations and production of ‘Chemlali’ olive trees (Olea europaea L.)

Water relations are a key factor limiting olive production. In this study, effects of plating density on physiological aspects and productivity of ‘Chemlali’ olive trees were analyzed under rain-fed conditions in four planting densities (156, 100, 69 and 51 trees ha⁻¹), in an experimental olive orchard located in the center of Tunisia. Seasonal changes in leaf relative water content (RWC), leaf water potential, stomatal conductance (g _s), CO₂ assimilation rate and tree production were studied. Accompanying the changes in leaf water status, all the monitored trees reduced leaf stomatal conductance (g _s) and photosynthetic rate (A) throughout the summer drought, mirroring the increase in soil moisture deficit and vapor pressure deficit. However, the decrease in gas exchange was much more pronounced in high planting densities than in low ones. Our results confirm that the increase of tree-to-tree water competition with planting density was significant in the dry climate of Tunisia. Thus, planting density is critical when planting new olive orchards in arid regions.     

Systematic bias and the phylogeny of Coleoptera—A response to Cai et al. (2022) following the responses to Cai et al. (2020)

Systematic bias is one of the major phylogenetic issues arising over the last two decades. Using methods designed to reduce compositional and rate heterogeneity, hence systematic bias, Cai and co-workers (2022) (= CEA22) reanalyzed the DNA sequence dataset for Coleoptera of Zhang et al. (2018) (= ZEA). CEA22 suggest that their phylogenetic results and major evolutionary hypotheses about the Coleoptera should be favoured over other recently published studies. Here, we discuss the methodology of CEA22 with particular attention to how their perfunctory reanalysis of ZEA obfuscates rather than illuminates beetle phylogeny. Similar to published rebuttals of an earlier study of theirs, we specifically find that many of their claims are misleading, unsupported, or false. Critically, CEA22 fail to establish the stated premise for their reanalysis. They fail to demonstrate how composition or rate heterogeneity supposedly impacted the phylogeny estimate of ZEA, let alone the results of other recent studies. Moreover, despite their claim of comprehensive sampling of Coleoptera, their dataset is neither the most diverse with respect to species and higher taxa included, nor anywhere near the largest in terms of sequence data and sampled loci. Although CEA22 does contribute additional fossils for calibration, those seeking the best available estimate for Coleoptera phylogeny and evolution based on molecular data are advised to look elsewhere.     

“Do not lose the winning games” to the 100th anniversary of M.E. Lobashev

Mikhail E. Lobashev (1907–1971), Head of the Department of Genetics and Breeding with the Leningrad (now, St. Petersburg) State University from 1957 to 1971, had traveled a long way from a homeless to an Honored Scientist of the Russian Federation. Lobashev was among the discoverers of chemical mutagenesis in Drosophila; he pioneered in connecting the mutation process and the repair of genetic material and developed the concept of signal inheritance. Through the entire Great Patriotic War, he served with the field forces, and defended his doctoral dissertation on the physiological hypothesis of mutation process in 1946 on the return to the University. In 1948, Mikhail Efimovich was discharged from the University, where he was the Dean of the Biological Faculty, as a Morganist. On his return to the University in 1957, Lobashev devoted all his energies to the restoration of genetic education in this country, wrote the first domestic genetic textbook in the post-Lysenko period, organized the research at the Department of Genetics and Breeding, and created the scientific school, whose representatives are still successfully working in the field of genetics.     

Morphological and antioxidant responses of Nopalea cochenillifera cv. Maya (edible Opuntia sp. “Kasugai Saboten”) to chilling acclimatization

To clarify the wintering ability of the cactus Nopalea cochenillifera cv. Maya (edible Opuntia sp., common name “Kasugai Saboten”), we investigated the effects of temperature and antioxidant capacity on chilling acclimatization. We analyzed the anatomy of cladode chlorenchyma tissue of plants exposed to light under chilling. We found that chilling acclimatization can be achieved by exposure to approximately 15 °C for 2 weeks and suggest that it is affected by whether or not antioxidant capacity can recover. The overwintering cacti had the thinnest cuticle but firm cuticular wax, which is important in the acquisition of low temperature tolerance under strong light. In cacti with severe chilling injury, round swollen nuclei with clumping chloroplasts were localized in the upper part (axial side) of the cell, as though pushed up by large vacuoles in the lower part. In overwintering cacti, chloroplasts were arranged on the lateral side of the cell as in control plants, but they formed pockets: invaginations with a thin layer of chloroplast stroma that surrounded mitochondria and peroxisomes. Specific cellular structural changes depended on the degree of chilling stress and provide useful insights linking chloroplast behavior and structural changes to the environmental stress response.

     

Correction to: Morphological and antioxidant responses of Nopalea cochenillifera cv. Maya (edible Opuntia sp. “Kasugai Saboten”) to chilling acclimatization

Journal of Plant Research -     

Photosynthetic capacity and temperature responses of photosynthesis of rubber trees (Hevea brasiliensis Müll. Arg.) acclimate to changes in ambient temperatures

The aim of this study was to assess the temperature response of photosynthesis in rubber trees (Hevea brasiliensis Müll. Arg.) to provide data for process-based growth modeling, and to test whether photosynthetic capacity and temperature response of photosynthesis acclimates to changes in ambient temperature. Net CO₂ assimilation rate (A) was measured in rubber saplings grown in a nursery or in growth chambers at 18 and 28°C. The temperature response of A was measured from 9 to 45°C and the data were fitted to an empirical model. Photosynthetic capacity (maximal carboxylation rate, V _cmax, and maximal light driven electron flux, J _max) of plants acclimated to 18 and 28°C were estimated by fitting a biochemical photosynthesis model to the CO₂ response curves (A–C _i curves) at six temperatures: 15, 22, 28, 32, 36 and 40°C. The optimal temperature for A (T _opt) was much lower in plants grown at 18°C compared to 28°C and nursery. Net CO₂ assimilation rate at optimal temperature (A _opt), V _cmax and J _max at a reference temperature of 25°C (V _cmax25 and J _max25) as well as activation energy of V _cmax and J _max (E _aV and E _aJ) decreased in individuals acclimated to 18°C. The optimal temperature for V _cmax and J _max could not be clearly defined from our response curves, as they always were above 36°C and not far from 40°C. The ratio J _max25/V _cmax25 was larger in plants acclimated to 18°C. Less nitrogen was present and photosynthetic nitrogen use efficiency (V _cmax25/N _a) was smaller in leaves acclimated to 18°C. These results indicate that rubber saplings acclimated their photosynthetic characteristics in response to growth temperature, and that higher temperatures resulted in an enhanced photosynthetic capacity in the leaves, as well as larger activation energy for photosynthesis.     

Genetic diversity and population structure of the Italian fungi belonging to the taxa Pleurotus eryngii (DC.:Fr.) Quèl and P. ferulae (DC.:Fr.) Quèl

A study using allozymes and PCR fingerprinting was conducted to estimate the genetic diversity of Italian populations of two economically important cultivated fungal taxa, Pleurotus eryngii and P. ferulae. Very little is known about the genetic diversity distribution pattern of these taxa. Heterozygote deficiency was observed at few loci; in fact the inbreeding coefficients were not high, which demonstrates that mechanisms restrain the inbreeding act at the local level. Estimates of genetic differentiation indicated a pattern of greater variation within, rather than between, populations. These results were supported by AMOVA analysis, which attributed a low proportion of the total genetic variation to large geographical scale divergence, and indicated that most of the genetic diversity was because of differences within populations. This distribution pattern of genetic variation of P. eryngii and P. ferulae populations seems to be the result of high gene flow, by efficient basidiospore dispersal, and outcrossing mechanisms, which restrain inbreeding within populations.     

Two Genes (ClS1 and ClF-box) Involved the Self-Incompatibility of ”Xiangshui” Lemon (Citrus limon (L.) Burm. f.)

Plant Molecular Biology Reporter - Gametophytic self-incompatibility (GSI) is an important factor affecting fruit development and is one of the important mechanisms of seedlessness in citrus....     

Differences in the floral anthocyanin content of violet–blue flowers of Vinca minor L. and V. major L. (Apocynaceae)

Two novel delphinidin 3-(tri or di)-glycoside-7-glycosides were isolated from the violet–blue flowers of Vinca minor L. and V. major L. (Family: Apocynaceae), and determined to be delphinidin 3-O-[2-O-(β-xylopyranosyl)-6-O-(α-rhamnopyranosyl)-β-galactopyranoside]-7-O-(α-rhamnopyranoside) [= delpphinidin 3-(2^G-xylosylrobinobioside)-7-rhamnoside] as major floral anthocyanin of V. minor and delphinidin 3-O-[6-O-(α-rhamnopyranosyl)-β-galactopyranoside]-7-O-(α-rhamnopyranoside) [= delpphinidin 3-robinobioside-7-rhamnoside] as major floral anthocyanin of V. major by chemical and spectroscopic methods. In addition, chlorogenic acid and kaempferol 3-O-[6-O-(α-rhamnopyranosyl)-β-galactopyranoside]-7-O-(α-rhamnopyranoside) [= kaempferol 3-robinobioside-7-rhamnoside (robinin)] were identified in these flowers. In this paper, the relation between the structure of floral anthocyanins and classification of Vinca species was discussed.     

About the Book by S.A. Kuz'min and E.N. Gudimova, “Introduction of the Kamchatka Red King Crab into the Barents Sea: Specifics of Biology,Fishing Prospects” (Apatity: Kola Science Center RAS, 2002, 236 pp.)

Russian Journal of Marine Biology -