Thermogenesis in Syngonium (Araceae)

2007 ◽  
Vol 85 (2) ◽  
pp. 184-190 ◽  
Author(s):  
Mathieu Chouteau ◽  
Denis Barabé ◽  
Marc Gibernau
Keyword(s):  
Heat Production ◽  
Stigma Receptivity ◽  
The Third ◽  
Female Phase ◽  
Male Phase

Floral cycles and spadix temperatures were recorded for two species of Syngonium: Syngonium schottianum Wendl. ex Schott (section Cordatum) and Syngonium angustatum Schott (section Syngonium). Both species exhibited a 3-day flowering cycle, beginning with stigma receptivity and opening of the spathe the first day, the female phase continues over the second day, and the male phase continues over the third day. These species displayed two distinct patterns of heat production during flowering. In S. schottianum, the spadix warmed up twice during the beginning of the second and third nights, but in S. angustatum, the spadix warmed up twice the second day, once the second night, and once the third day. These different thermogenic cycles are discussed in regard to other genera that are phylogenetically close or sharing similar flowering and thermogenic cycles.

Reproductive Function in the Mimosoid Legume Acacia retinodes: Ultrastructural and Cytochemical Characteristics of Stigma Receptivity

1989 ◽  
Vol 37 (2) ◽  
pp. 103 ◽  
Author(s):  
RB Knox ◽  
J Kenrick ◽  
S Jobson ◽  
C Dumas
Keyword(s):  
Fatty Acids ◽  
Reproductive Function ◽  
Stigma Receptivity ◽  
Flower Opening ◽  
Flavonoid Aglycones ◽  
Browning Reaction ◽  
Female Phase ◽  
Male Phase ◽  
The Moment ◽  
Stigma Exudate

The stigma of Acacia retinodes is receptive from the moment the flower opens (female phase). Receptivity, assessed in terms of pod set, is highest at flower opening, and lowest the following day (male phase). Stigma receptivity is associated with the acquisition of a heterogeneous stigma exudate, the components of which are secreted sequentially during differentiation. Cytochemical probes have tentatively identified the principal components as unsaturated and saturated lipids, free fatty acids, flavonoid aglycones, carbohydrates, proteins and phenolic compounds. The onset of male phase in unpollinated stigmas is associated with a breakdown of the plasma membrane and organelle membranes of stigma cells, and subsequently a browning reaction.

Pollination of Amorphophallus johnsonii (Araceae) by carrion beetles (Phaeochrous amplus) in a Ghanaian rain forest

1996 ◽  
Vol 12 (3) ◽  
pp. 409-418 ◽  
Author(s):  
Daniel D. N. Beath
Keyword(s):  
Rain Forest ◽  
Rainy Season ◽  
Male Inflorescence ◽  
Large Numbers ◽  
Female Phase ◽  
Male Phase ◽  
Carrion Beetles ◽  
Main Rainy Season

ABSTRACTAmorphophallus johnsonii (N. E. Brown) flowers during April in the main rainy season in Ghana. Anthesis starts at dusk with fluid oozing from the upper spadix accompanied by a strong aminoid odour. Just after dark large numbers of carrion beetles (Phaeochrous amplus) and occasional dung fly species (Hemigymnochaeta unicolor and Paryphodes tigrinus) visit the inflorescences. The beetles become trapped in the lower spathe overnight and remain in the spadix until the following evening. Between 1630 and 1645 h the following day, the anthers produce long threads of sticky pollen. The trapped beetles escape just after dark by crawling up the spadix, past the dehisced anthers and fly away from the spadix tip. Marked beetles were seen to transfer pollen from male phase to female phase inflorescences. Successful fertilisation was only effected if pollen was transferred on the same night from a male inflorescence 30 m or less away. Pollen is psilate and typical of beetle pollinated Araceae. Berries ripen approximately 70 d after fertilization and ripen basisetally in the infructescence.

scholarly journals Male flowers of Aconitum compensate for toxic pollen with increased floral signals and rewards for pollinators

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
A.-L. Jacquemart ◽  
C. Buyens ◽  
M.-F. Hérent ◽  
J. Quetin-Leclercq ◽  
G. Lognay ◽  
...  
Keyword(s):  
Larval Food ◽  
Chemical Defences ◽  
Toxic Nectar ◽  
Pollen Transfer Efficiency ◽  
Aconitum Napellus ◽  
Female Phase ◽  
Male Phase ◽  
Male Flowers ◽  
Nectar Rewards ◽  
Toxic Pollen

Abstract Many plants require animal pollinators for successful reproduction; these plants provide pollinator resources in pollen and nectar (rewards) and attract pollinators by specific cues (signals). In a seeming contradiction, some plants produce toxins such as alkaloids in their pollen and nectar, protecting their resources from ineffective pollinators. We investigated signals and rewards in the toxic, protandrous bee-pollinated plant Aconitum napellus, hypothesizing that male-phase flower reproductive success is pollinator-limited, which should favour higher levels of signals (odours) and rewards (nectar and pollen) compared with female-phase flowers. Furthermore, we expected insect visitors to forage only for nectar, due to the toxicity of pollen. We demonstrated that male-phase flowers emitted more volatile molecules and produced higher volumes of nectar than female-phase flowers. Alkaloids in pollen functioned as chemical defences, and were more diverse and more concentrated compared to the alkaloids in nectar. Visitors actively collected little pollen for larval food but consumed more of the less-toxic nectar. Toxic pollen remaining on the bee bodies promoted pollen transfer efficiency, facilitating pollination.

scholarly journals Sex-related differences in local and whole-body heat loss responses: Physical or physiological?

2014 ◽  
Vol 39 (7) ◽  
pp. 843-843
Author(s):  
Daniel Gagnon
Keyword(s):  
Sex Differences ◽  
Heat Loss ◽  
Heat Production ◽  
Experimental Studies ◽  
Metabolic Heat Production ◽  
Whole Body ◽  
Fixed Rate ◽  
The Third ◽  
Metabolic Heat ◽  
Body Heat

The current thesis examined whether sex differences in local and whole-body heat loss are evident after accounting for confounding differences in physical characteristics and rate of metabolic heat production. Three experimental studies were performed: the first examined whole-body heat loss in males and females matched for body mass and surface area during exercise at a fixed rate of metabolic heat production; the second examined local and whole-body heat loss responses between sexes during exercise at increasing requirements for heat loss; the third examined sex-differences in local sweating and cutaneous vasodilation to given doses of pharmacological agonists, as well as during passive heating. The first study demonstrated that females exhibit a lower whole-body sudomotor thermosensitivity (553 ± 77 vs. 795 ± 85 W·°C−1, p = 0.05) during exercise performed at a fixed rate of metabolic heat production. The second study showed that whole-body sudomotor thermosensitivity is similar between sexes at a requirement for heat loss of 250 W·m−2 (496 ± 139 vs. 483 ± 185 W·m−2·°C−1, p = 0.91) and 300 W·m−2 (283 ± 70 vs. 211 ± 66 W·m−2·°C−1, p = 0.17), only becoming greater in males at a requirement for heat loss of 350 W·m−2 (197 ± 61 vs. 82 ± 27 W·m−2·°C−1, p = 0.007). In the third study, a lower sweat rate to the highest concentration of acetylcholine (0.27 ± 0.08 vs. 0.48 ± 0.13 mg·min−1·cm−2, p = 0.02) and methacholine (0.41 ± 0.09 vs. 0.57 ± 0.11 mg·min−1·cm−2, p = 0.04) employed was evidenced in females, with no differences in cholinergic sensitivity. Taken together, the results of the current thesis show that sex itself can modulate sudomotor activity, specifically the thermosensitivity of the response, during both exercise and passive heat stress. Furthermore, the results of the third study point towards a peripheral modulation of the sweat gland as a mechanism responsible for the lower sudomotor thermosensitivity in females.

scholarly journals Linking pollinator efficiency to patterns of pollen limitation: small bees exploit the plant–pollinator mutualism

2018 ◽  
Vol 285 (1880) ◽  
pp. 20180635 ◽  
Author(s):  
Matthew H. Koski ◽  
Jennifer L. Ison ◽  
Ashley Padilla ◽  
Angela Q. Pham ◽  
Laura F. Galloway
Keyword(s):  
Pollen Limitation ◽  
Pollen Deposition ◽  
Pollinator Efficiency ◽  
Flower Visitation ◽  
Female Phase ◽  
Male Phase ◽  
Single Flower ◽  
Floral Visitation ◽  
Low Efficiency ◽  
Plant Pollinator

Seemingly mutualistic relationships can be exploited, in some cases reducing fitness of the exploited species. In plants, the insufficient receipt of pollen limits reproduction. While infrequent pollination commonly underlies pollen limitation (PL), frequent interactions with low-efficiency, exploitative pollinators may also cause PL. In the widespread protandrous herb Campanula americana , visitation by three pollinators explained 63% of the variation in PL among populations spanning the range. Bumblebees and the medium-sized Megachile campanulae enhanced reproductive success, but small solitary bees exacerbated PL. To dissect mechanisms behind these relationships, we scored sex-specific floral visitation, and the contributions of each pollinator to plant fitness using single flower visits. Small bees and M. campanulae overvisited male-phase flowers, but bumblebees frequently visited female-phase flowers. Fewer bumblebee visits were required to saturate seed set compared to other bees. Scaling pollinator efficiency metrics to populations, small bees deplete large amounts of pollen due to highly male-biased flower visitation and infrequent pollen deposition. Thus, small bees reduce plant reproduction by limiting pollen available for transfer by efficient pollinators, and appear to exploit the plant–pollinator mutualism, acting as functional parasites to C. americana . It is therefore unlikely that small bees will compensate for reproductive failure in C. americana when bumblebees are scarce.

scholarly journals Intraspecific Seasonal Variation of Flowering Synchronization in a Heterodichogamous Tree

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1509
Author(s):  
Noemi Tel-Zur ◽  
Tamar Keasar
Keyword(s):  
Genetic Diversity ◽  
Seasonal Variation ◽  
Phase Duration ◽  
Male And Female ◽  
Flowering Synchrony ◽  
Flowering Season ◽  
Hand Pollination ◽  
Female Phase ◽  
Male Phase ◽  
Phase Differences

Heterodichogamous reproduction in plants involves two flowering morphs, reciprocal in their timing of male and female sexual functions. The degree of synchrony in floral sex phase, within and between individuals of each morph, determines the flowers’ potential fertilization partners. Complete within-morph synchrony enables across-morph mating alone, whereas unsynchronized floral sex phases may allow fertilization within a plant individual (geitonogamy) or within a morph. We documented the disruption of flowering synchrony in the heterodichogamous Ziziphus spina-christi towards the end of its seven-month flowering season. This desert tree has self-incompatible, protandrous, short-lived (2-day) flowers that open before dawn (‘Early’ morph) or around noon (‘Late’ morph). We counted flowers in the male and female phase on flowering branches that were sampled monthly during the 2016–2018 flowering seasons. In 2018, we also tagged flowers and followed their sex-phase distributions over two days at the start, middle, and end of the season. The switch to the female phase was delayed at the end-season (November-December), and 74% of the flowers did not develop beyond their male phase. Differences in male-phase duration resulted in asynchrony among flowers within each tree and among trees of both flowering morphs. Consequently, fertilization between trees of the same morph becomes potentially possible during the end-season. In controlled hand-pollination assays, some within-morph fertilizations set fruit. The end-season breakdown of synchronous flowering generates variability within morphs and populations. We suggest that this variability may potentially enable new mating combinations in a population and enhance its genetic diversity.

Effect of confinement in a respiration chamber and changes in temperature and plane of nutrition on heat production of 25 kg pigs

1980 ◽  
Vol 95 (1) ◽  
pp. 123-133 ◽  
Author(s):  
R. Gray ◽  
K. J. McCracken
Keyword(s):  
Carbon Dioxide ◽  
Energy Intake ◽  
Heat Production ◽  
Environmental Temperature ◽  
Normal Range ◽  
Respiration Chamber ◽  
The Third ◽  
Lower Critical Temperature ◽  
The Mean ◽  
Range Of Variation

SummaryA closed-circuit respiration chamber was used to study (a) the effect of confinement in a chamber on the heat production of pigs already accustomed to restraint in a metabolism cage; (b) changes in daily heat production of pigs following a reduction in the energy intake; and (c) the effect of increasing or decreasing the environmental temperature.An automatically recharged version of the oxygen burette used by Waring & Brown (1965) is described. During tests of the chamber and burette system the mean recoveries of carbon dioxide and oxygen were, respectively, 0·994 and 0·995.It is concluded that measurements of heat production on the first day of confinement were within the normal range of variation and provided valid estimates of energy expenditure.The minimum value for the respiratory quotient (RQ) occurred on the third day following a reduction in energy intake, and it is concluded that the direct effect of previously ingested nutrients was eliminated by the third day. However, there appeared to be a further decline in heat production until 6–7 days following the reduction in energy intake.The heat production of singly caged pigs fed almost to appetite was similar at 22 and 29 °C. Heat production increased at 15 °C, indicating that this was below the lower critical temperature of fed 25 kg pigs. The response of heat production to the low temperature continued for at least 18 days. Variations in heat production between animals and litters were as high as 15% in three experiments.

scholarly journals Induction of Diploid Eggs With Colchicine During Embryo Sac Development in Populus

2010 ◽  
Vol 59 (1-6) ◽  
pp. 40-48 ◽  
Author(s):  
J. Wang ◽  
X. Y. Kang ◽  
D. L. Li ◽  
H. W. Chen ◽  
P. D. Zhang
Keyword(s):  
Generative Cell ◽  
Embryo Sac ◽  
Mitotic Division ◽  
Chromosome Counting ◽  
Paraffin Sections ◽  
Stigma Receptivity ◽  
The Third ◽  
Embryo Sac Development ◽  
2N Eggs ◽  
Colchicine Solution

Abstract Diploid (2n) eggs were induced by treating developing embryo sacs of Populus with colchicine solution, in order to produce triploid plants. The optimal pollinated time of female catkins was confirmed as timing point for each treatment. When female catkins of P. pseudo-simonii x P. nigra ‘Zheyin3#’ had become 5.62 ± 0.13 cm long 84 h after they emerged from their bract scales and all stigmas were exposed, pistils all over the entire catkin had optimal stigma receptivity. Observation of paraffin sections showed that embryo sac development of ‘Zheyin3#’, which initiated 12 h before pollination and finished 132 h after pollination, was a successive and asynchronous process. Generative cell division of pollen of the male parent P. x beijingensis took place 3-16 h after pollination. Catkins of 18-96 h after pollination of ‘Zheyin3#’ were treated with colchicine solution. In the progeny, twenty three triploids were detected by chromosome counting and the highest rate of triploids was 66.7% in one treatment. The rate of triploid yield was positively correlated with the frequency of four-nucleate embryo sacs (r = 0.6721, p = 0.0981) and was not significantly correlated with the percentages of uni-, twoand eight-nucleate embryo sac (r = -0.1667, p = 0.7210, r = -0.3069, p = 0.5031 and r = 0.0189, p = 0.9679, respectively), suggesting that the third mitotic division of embryo sac may be the effective stage to induce 2n eggs. Through this approach, completely homozygous 2n eggs can be produced. Its significance for plant breeding is discussed.

scholarly journals Nectar secretion and pollen production in protandrous flowers of Campanula patula L. (Campanulaceae)

2018 ◽  
Vol 71 (1) ◽  
Author(s):  
Bożena Denisow ◽  
Monika Strzałkowska-Abramek ◽  
Małgorzata Wrzesień
Keyword(s):  
Sugar Accumulation ◽  
Reproductive Costs ◽  
Pollen Production ◽  
Nectar Secretion ◽  
Mass Content ◽  
Plastic Response ◽  
Male And Female ◽  
Functional Relationships ◽  
Female Phase ◽  
Male Phase

Nectar secretion was noted both in the male and female floral phases of the protandrous flowers of <em>Campanula patula</em> (Campanulaceae). Female-biased sugar accumulation was evidenced and plasticity in the duration of sexual phases observed. Flowers in the male phase produced twofold less nectar with lower sugar concentrations compared to female-phase flowers. The sugar mass content averaged 0.6 mg ±0.45 <em>SD</em> per flower in the male phase and 1.4 ±0.5 <em>SD</em> per flower in the female phase. The pollen mass averaged 0.16 mg ±0.10 <em>SD</em> per flower. An understanding of the evolution of functional relationships between floral sexes requires consideration of the compensation of the reproductive costs, including the plastic response to interdependent factors, i.e., photosynthesis and growth, the effect of pollinators, pollen robbers, and external environmental forces.

Within and among flower sex-phase distribution in Alstroemeria aurea (Alstroemeriaceae)

1995 ◽  
Vol 73 (12) ◽  
pp. 1986-1994 ◽  
Author(s):  
Marcelo A. Aizen ◽  
Alicia Basilio
Keyword(s):  
Inbreeding Depression ◽  
Seed Set ◽  
Phase Distribution ◽  
Selfing Rate ◽  
Pollen Transfer ◽  
Alstroemeria Aurea ◽  
Female Phase ◽  
Male Phase ◽  
Male To Female ◽  
Simultaneous Change

Although dichogamy is a prevailing feature of the angiosperms, the simultaneous change from male to female phases among hermaphrodite flowers within a plant (i.e., synchronous protandry) has been reported for only a few families (e.g., Araliaceae, Umbelliferae). Here we present an example of synchronous protandry at the ramet level in the Alstroemeriaceae. Dichogamy was analyzed in clonal Alstroemeria aurea at the flower, ramet, and at the whole flowering patch level. Alstroemeria aurea is self-compatible but totally dependent on biotic agents for pollen transfer. There was evidence of strong inbreeding depression expressed during seed development. Comparisons of seed set in open-pollinated flowers with those obtained after hand selfing and outcrossing resulted in a selfing rate of 0.3. At the flower level protandry was complete. The male phase lasted about 4 days and the female phase lasted about 3 days. Between the female and male phase, there was an approximately 1-day long "neuter" phase. Flowering ramets produce a terminal inflorescence bearing one or more whorls of flowers. Within a ramet, flowers of the same order opened within a period of 1–2 days, and male and female phases of different flowers did not overlap. When inflorescences held two whorls of flowers, the ramet went through two alternating non-overlapping male–female cycles. Using spatial autocorrelation techniques, we found little evidence for pairs of neighboring ramets expressing the same sexual phase beyond random expectations at any scale ranging between 0.25 to 15 m. By ensuring pollen interchange between flowering ramets, synchronized protandry at the ramet level could be an important feature in reducing selfing in A. aurea. Key words: Alstroemeria aurea, dichogamy, synchronous protandry, inbreeding depression.

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