Initiation of Flowering in Protea compacta × Protea neriifolia Hybrid ‘Carnival’ Coincides with Expression of the FLOWERING LOCUS T Homologue

The Protea hybrid ‘Carnival’ (Protea compacta × Protea neriifolia) is responsive to seasonal change, arresting growth during the winter and producing flowers in the late summer after initiating flowering during the elongation of the spring flush. The large commercially attractive flower heads, consisting of over 200 florets, develop over a period of months. To begin to better understand the molecular factors that influence the transition to flowering in Protea, a homologue of the FLOWERING LOCUS T (FT) gene, ProFT, was isolated from ‘Carnival’, and its expression was analysed. ProFT showed increased expression in ‘Carnival’ leaves during October (13 h light/11 h dark; average daily temperature of 17 °C) at the time that floral organs were being pre-formed in the meristem. ProFT expression was fivefold higher in florally determined buds compared to that in leaves, and low levels were present in the vegetative meristems analysed. These results suggest that ProFT may act as a seasonally regulated floral inducer in ‘Carnival’, but based on spatial expression, data is also likely to play a role in inflorescence development and growth architecture.     

How important is the relationship between Protea humiflora (Proteaceae) and its non-flying mammal pollinators?

The interaction between Protea humiflora and its non-flying mammal pollinators was investigated with the aim of quantifying the relationship for both the plants and mammals involved. We manipulated flower density by inflorescence removal and determined the effect upon mammal captures, and excluded mammals to determine their effect upon seed set. Of three mammal species captured frequently, the smallest, Acomys subspinosus (18dž SD g, Rodentia: Muridae), demonstrated the strongest relationship with P. humiflora. Breeding coincided with flowering, and pollen constituted 33.5ᆯ.5% by volume (max 80%, n=19) of winter scats. Acomys captures on control grids were twice those on inflorescence-removal grids during flowering. Aethomys namaquensis (51ᆢ g, Rodentia: Muridae) included flower products in its diet (pollen comprising 3.2dž.9% of winter scats, n=73), but captures were not affected by inflorescence removal. Aethomys is a seasonal breeder and juveniles entered the population 2 months after flowering. Elephantulus edwardii, although an insectivore (48lj g, Macroscelidea: Macroscelididae), carried more pollen grains on its nose than the rodents, acquired while foraging in inflorescences for insects. Pollen comprised 3.1LJ.4% (n=23) of winter scats. From the plant perspective, seed set was significantly reduced in caged inflorescences and in those >20 cm above the ground, presumably due to limited accessibility by terrestrial animals. We conclude that small mammals are responsible for around half (56%) of the effective seed set in P. humiflora.     

Are Protea populations seed limited? Implications for wildflower harvesting in Cape fynbos

Abstract Little is known about the extent to which plant population growth is limited by seed production. We studied two non-sprouting Protea species, both entirely dependent on seeds for recruitment after fire, to determine how flower harvesting would affect the size of the next generation after burning. Five harvesting treatments (0, 25, 50, 75 and 100% inflorescence removal) were applied, each replicated four times in 10 × 10m plots. Seedbanks were censused before a late-summer burn for each species and each replicate. The mean proportion of seeds surviving the burn until germination the following spring was 0.46 for Protea repens and 0.57 for Protea neriifolia. Of the seedlings that emerged, 90% and 55%, respectively, survived the first summer drought. Flower production in the 9 year old stand was strongly related to population density. Optimal plant densities for maximum flower production were estimated as 150 for P. repens and 70 for P. neriifolia. These target densities were greatly exceeded by seedling populations surviving the first summer drought in unharvested stands. If future density-independent mortality is negligible, the excess represents that part of the seedbank that could have been harvested before the burn without influencing future flower production. We developed a simple static model for setting flower harvesting levels in these seed-saturated populations. The predicted harvesting levels (50% of inflorescences in P. repens and 85% in P. neriifolia) were validated against the experimental harvests. We discuss the sensitivity of harvesting levels to variation in fecundity/density relationships, seed survival through a burn and seedling survival until flowering, and the implications for flower harvesting.     

Did the evolution of the phytoplankton fuel the diversification of the marine biosphere?

We discuss the possible links between the fossil record of marine biodiversity, nutrient availability and primary productivity. The parallelism of the fossil records of marine phytoplankton and faunal biodiversity implicates the quantity (primary productivity) and quality (stoichiometry) of phytoplankton as being critical to the diversification of the marine biosphere through the Phanerozoic. The relatively subdued marine biodiversity of the Palaeozoic corresponds to a time of relatively low macronutrient availability and poor food quality of the phytoplankton as opposed to the diversification of the Modern Fauna through the Mesozoic–Cenozoic. Increasing nutrient runoff to the oceans through the Phanerozoic resulted from orogeny, the emplacement of Large Igneous Provinces (LIPs), the evolution of deep-rooting forests and the appearance of more easily decomposable terrestrial organic matter that enhanced weathering. Positive feedback by bioturbation of an expanding benthos played a critical role in evolving biogeochemical cycles by linking the oxidation of dead organic matter and the recycling of nutrients back to the water column where they could be re-utilized. We assess our conclusions against a recently published biogeochemical model for geological time-scales. Major peaks of marine diversity often occur near rising or peak fluxes of silica, phosphorus and dissolved reactive oceanic phosphorus; either major or minor ⁸⁷Sr/⁸⁶Sr peaks; and frequently in the vicinity of major (Circum-Atlantic Magmatic Province) and minor volcanic events, some of which are associated with Oceanic Anoxic Events. These processes appear to be scale-dependent in that they lie on a continuum between biodiversification on macroevolutionary scales of geological time and mass extinction.     

Is the Octomacridae the sister family of the Diplozodae?

Diplozoidae and Octomacridae are usually considered as sister families. Essentially this is because they are the only polyopisthocotyleans parasitising primary freshwater teleosts. Because of the lack of phylogenetically informative morphological characters to explore the pattern of colonisation of the primary continental freshwater teleosts and in order to understand the appearance of the "natural parabiosis" of Diplozoidae, a molecular phylogeny was inferred by comparing newly obtained partial 28S and 18S rDNA gene sequences of Eudiplozoon nipponicum and Diplozoon homoion with other already available sequences. The phylogenetic analysis seems to show that Diplozoidae and Octomacridae are not sister groups. Thus, the colonisation of primary freshwater teleosts by these two families could be independent.     

Imperfect Batesian mimicry—the effects of the frequency and the distastefulness of the model

Batesian mimicry is the resemblance between unpalatable models and palatable mimics. The widely accepted idea is that the frequency and the unprofitability of the model are crucial for the introduction of a Batesian mimic into the prey population. However, experimental evidence is limited and furthermore, previous studies have considered mainly perfect mimicry (automimicry). We investigated imperfect Batesian mimicry by varying the frequency of an aposematic model at two levels of distastefulness. The predator encountered prey in a random order, one prey item at a time. The prey were thus presented realistically in a sequential way. Great tits (Parus major) were used as predators. This experiment, with a novel signal, supports the idea that Batesian mimics gain most when the models outnumber them. The mortalities of the mimics as well as the models were significantly dependent on the frequency of the model. Both prey types survived better the fewer mimics there were confusing the predator. There were also indications that the degree of distastefulness of the model had an effect on the survival of the Batesian mimic: the models survived significantly better the more distasteful they were. The experiment supports the most classical predictions in the theories of the origin and maintenance of Batesian mimicry.     

Phytochemicals: the good, the bad and the ugly?

Phytochemicals are constitutive metabolites that enable plants to overcome temporary or continuous threats integral to their environment, while also controlling essential functions of growth and reproduction. All of these roles are generally advantageous to the producing organisms but the inherent biological activity of such constituents often causes dramatic adverse consequences in other organisms that may be exposed to them. Nevertheless, such effects may be the essential indicator of desirable properties, such as therapeutic potential, especially when the mechanism of bioactivity can be delineated. Careful observation of cause and effect, followed by a coordinated approach to identify the responsible entities, has proved extremely fruitful in discovering roles for phytochemical constituents. The process is illustrated by selected examples of plants poisonous to animals and include the steroidal alkaloid toxin of Veratrum californicum (Western false hellebore), piperidine alkaloids of Lupinus species (lupines), and polyhydroxy indolizidine, pyrrolizidine and nortropane alkaloids of Astragalus and Oxytropis species (locoweeds), Castanospermum australe (Moreton Bay chestnut) and Ipomoea species (morning glories).     

Effect of cortisone on the developmental pattern of the neutral and the acid β-galactosidases of the small intestine of the rat

1. The developmental pattern and effect of cortisone on acid beta-galactosidase and neutral beta-galactosidase were studied in postnatal rats by a recently proposed method for their independent determination. 2. After birth the acid beta-galactosidase activity increases in the ileum, whereas it decreases slightly in the jejunum. On day 16 after birth the activity in the ileum decreases and in 20-day-old rats activity in both parts of the intestine decreases to adult values. In suckling animals the activity in the ileum exceeds the jejunal activity severalfold and in adult animals the activity in the jejunum is slightly higher than that in the ileum. 3. Neutral beta-galactosidase activity is high after birth and decreases in both jejunum and ileum after day 20 after birth. In 12-20-day-old rats activity in both parts is essentially the same, but in adult animals jejunal activity exceeds ileal activity four-to five-fold. 4. Cortisone (0.5, 2.0 or 5.0mg/100g body wt. daily for 4 days) does not influence the activity of either enzyme in 60-day-old rats. Acid beta-galactosidase activity is decreased after cortisone treatment in 8-, 12-, 16-and 18-day-old rats, with sensitivity to cortisone increasing with the approach of weaning. No effect of cortisone on acid beta-galactosidase is seen in 8-day-old rats. Neutral beta-galactosidase activity is increased in the ileum of 8-, 12-, 16- and 18-day old rats, but only in the jejunum of 8-and 12-day-old rats.     

Is Mislocalization during Saccades Related to the Position of the Saccade Target within the Image or to the Gaze Position at the End of the Saccade?

A stimulus that is flashed around the time of a saccade tends to be mislocalized in the direction of the saccade target. Our question is whether the mislocalization is related to the position of the saccade target within the image or to the gaze position at the end of the saccade. We separated the two with a visual illusion that influences the perceived distance to the target of the saccade and thus saccade endpoint without affecting the perceived position of the saccade target within the image. We asked participants to make horizontal saccades from the left to the right end of the shaft of a Müller-Lyer figure. Around the time of the saccade, we flashed a bar at one of five possible positions and asked participants to indicate its location by touching the screen. As expected, participants made shorter saccades along the fins-in (<–>) configuration than along the fins-out (>–<) configuration of the figure. The illusion also influenced the mislocalization pattern during saccades, with flashes presented with the fins-out configuration being perceived beyond flashes presented with the fins-in configuration. The difference between the patterns of mislocalization for bars flashed during the saccade for the two configurations corresponded quantitatively with a prediction based on compression towards the saccade endpoint considering the magnitude of the effect of the illusion on saccade amplitude. We conclude that mislocalization is related to the eye position at the end of the saccade, rather than to the position of the saccade target within the image.     

Does the weight of the brain depend on the body height?]

Brains of 1664 subjects (895 males and 769 females) aged from 20 to 89 years have been studied. The whole material being investigated was divided, within sex groups, into body-height classes and age classes. The class interval within the age classes was 10 years, that in height classes 5 cm. Mean arithmetics, standard deviations, standard error as well as coefficients of variation and correlation for respective classes have been calculated. It has been ascertained that the brain weight depends on the body height. In tall subjects no brains of extremely low absolute weight are encountered and, adversely, high brain weight is seldom met in short individuals. The body height also exerts certain influence upon the relative weight of the brain. More favourable proportion between the brain weight and the body length has been revealed in short subjects. Tall individuals are characterized by a low relative weight of the brain. It should be supposed that the spinal cord weight is higher in the latter subjects. The differences between the mean absolute weight of women's brains and that in men of the same age class are conditioned by the difference in the body length. A constant magnitude of difference in the mean brain weight in subjects of the same body height claims 100 g. The paper provides 2 enclosed tables representing obtained results for arithmetic mean of the absolute brain weight both in the age classes and body height classes. The differences between the mean weights of brains in women as well as in men are not significant. The coefficient of correlation between the brain weight and the body height is for men r male1 = 0.2008 for women r female1 = 0.2630, wherease the coefficient of regression for the brain weight is r male2 = 3.67 and r female2 = 3.906 respectively.     

Does DNA alone determine the development of the organism? (the information aspect of the problem)

Two closely related controversial problems are discussed: whether the developmental processes can be reduced to the synthesis of polypeptides encoded in DNA, and whether the information in DNA is equivalent to that in the adult organism. Critically considered are the ideas that DNA is only responsible for the protein synthesis, whereas morphogenesis proceeds independently and according to epigenetic regularities of its own. It is stated that development is the realization of genetic information in which more elementary (molecular) processes unambiguously determine a more complex cellular level which in its turn determines morphogenesis of tissues and organs. Various mechanisms of the appearance of new information in the course of development are considered. The statement is made that new information concerns only some individual characters of the organism, whereas most of information that determines the process of development and the structure of the adult organism is created in the course of evolution, is stored in DNA and inherited.