Carnivore olfactory bulb size: allometry, phylogeny and ecology

Olfactory bulb size was measured in 146 species of Carnivora in order to examine whether recently observed functional patterns for overall brain size were similar for component parts of the brain. Comparative measures were analysed in relation to various allometric characters (body, brain and skull size), phylogeny, behaviour and ecology. Olfactory bulbs are significantly and positively correlated with all allometric variables, but indices of skull size correlate slightly more closely than other variables. This probably relates to functional aspects of skull size, facial proportions, and anterior elements of the brain. Phylogenetic associations were examined by two comparative methods: the method of independent contrasts and phylogenetic autoregression. Both revealed similar phylogenetic correlation at generic and familial levels. Using calculated values from either method, relative olfactory bulb size only correlates with zonation among seven behavioural and ecological variables; aquatic otters have smaller bulb sizes than carnivores of other zonal types. This agrees with discussion about the diminution of olfactory communication in aquatic environments. Also, olfactory bulb size correlates with home range size, which is consistent with a recent model on the use of olfaction for foraging in designated home ranges. Generally, comparative differences in olfactory bulb size in carnivores do not associate with functional variables found in other comparative studies. Nevertheless, future analyses of specific brain components in mammals may be more useful than overall brain size for testing evolutionary hypotheses of mammalian brain size.     

Tunicate bulb size variation in monocots explained by temperature and phenology

Plant bulbs are modified shoot systems comprised of short internodes with apical bud(s) surrounded by layers of leaf bases. Bulb diameters can vary greatly, with overall bulb size playing a role in flower formation and resource allocation. Despite the importance of bulb size to the overall fitness of an individual, evolutionary and ecological aspects of this trait have been almost completely neglected. Examining over 2,500 herbarium vouchers for 115 selected species, we analyzed monocot tunicate bulb size within a phylogenetic context in order to investigate its evolutionary significance. We recorded two bulb diameter optima and observed that as bulb size increases taxa inhabit warmer areas with less temperature seasonality. Furthermore, we found that hysteranthous taxa, a habit where leaves emerge separately from flowers, exhibit overall larger bulbs potentially due to reliance upon belowground stored resources to flower rather than on current environmental inputs. This work highlights the importance of including the belowground portion of plants into ecological and evolutionary studies in order to gain a more complete understanding of the evolution of plant forms and functions.     

Bulbing in Onions: Photoperiod and Temperature Requirements and Prediction of Bulb Size and Maturity

Bulb size and maturity are key characteristics of an onion cropand the onset of bulbing is an important determinant of these.In this paper we describe an experiment in which bulb and neckdiameter and leaf number were measured in onion crops (cultivarsPukekohe Longkeeper and Early Longkeeper) with different sowingdates planted at two different locations in New Zealand. A sensitiveindicator of earliest time of bulbing was developed using theratio of bulb and neck diameters and the statistical techniqueof cusums. Bulb diameter at bulbing was related to thermal timeaccumulated prior to bulbing. Bulbing only occurred when dualthresholds of a minimum thermal time of 600 degree days anda photoperiod of 13.75 h were reached. Mathematical relationshipswere developed between leaf number, sowing date, bulbing dateand bulb growth and maturity. Final bulb size could be predictedfrom bulb size at bulbing and number of leaves produced afterbulbing. Bulb maturity date could be predicted by number ofleaves after bulbing. Allium cepa L.; onion; temperature; photoperiod; bulb-neck ratio; leaf number; bulbing     

Ultrastructure and distribution of identified neurosecretory terminals in the sinus gland of the terrestrial isopod Oniscus asellus

An ultrastructural study of the sinus gland of the terrestrial isopod, Oniscus asellus, reveals that this structure consists of two regions: the bulb, which is attached by a narrow stalk to the optic lobe, and the lateral extension, which extends from the bulb along the optic tract to the compound eye. The bulb has a distal region containing only neurosecretory terminals, and a proximal region containing terminals, glial cells, and axons that give rise to the distally located terminals. In total, the sinus gland contains five types of terminals which can be distinguished by their location and the appearance of their neurosecretory granules. Three terminal types are located in the bulb and two in the lateral extension. The size of the terminals in the bulb varies among the three types, but the number of terminals is approximately the same for each type. Conversely, the two terminal types in the lateral extension are similar in size, but differ in number. Axons of two terminal types in the bulb can be traced to the central region of the protocerebrum; axons of one terminal type in the bulb and of terminals in the lateral extension can be traced to the optic lobe.     

Cribriform plate of ethmoid, olfactory bulb and olfactory acuity in forty species of bats

Relationships between the cribriform plate of the ethmoid, the olfactory bulb, and olfactory acuity were explored using material from 13 of the 17 bat families. All megachiropteran cribriform plates were entirely perforated. In contrast, microchiropteran plates showed distinct perforated portions dorsally and nonperforated portions ventrally. The plates of frugivorous species had more foramina than those of insectivorous ones. Bats with mixed dietary habits were intermediate. Our data suggest that the Chilonycterinae were originally frugivorous, and have only secondarily reverted to an insectivorous diet. Trend analyses show that wherever dietary preference appears to favor a more acute sense of smell, bulb diameter tends to be larger. In general, frugivorous bats tend to have bulbs exceeding 2 mm in diameter; insectivorous bats tend to have bulb diameters of 2 mm or less. The number of foramina in the plates and total cribriform plate area tends to increase as a function of bulb area, but the plate area the foramina occupied increases as a function of bulb volume. The ratio of the size of the bulb to the size of the cerebral hemisphere does not predict olfactory acuity in bats.     

Bulb Development in Onion (Allium cepa L.) III. Effects of the Size of Adjacent Plants, Shading by Neutral and Leaf Filters, Irrigation and Nitrogen Regime and the Relationship between the Red: Far-red Spectral Ratio in the Canopy and Leaf Area Index

Field experiments were done to investigate why onion crops witha high leaf area index (LAI) initiate bulb scales and maturesooner than those with a low LAI. When small plants were growneither mixed with large plants or in pure stands, those in themixed stands initiated bulb scales earlier than those in purestands. The timing of bulb development therefore depended onthe size of neighbouring plants and the LAI of the stand andwas not simply determined by the size or age of individual plants.Shading plots with neutral filters which caused no spectralchanges slightly accelerated bulb development compared to unshadedplots but shading by a canopy of climbing pea and bean leaveshad a larger effect. Lack of irrigation advanced bulb maturitybut in the highly irrigated treatments plots of high plant densitystill initiated bulb scales and matured before those of lowdensity. Quantitative relationships between the change in R : FR andeither LAI or total radiation interception were determined foronion leaf canopies. It is suggested that the decrease in thered to far-red spectral ratio (R : FR) as LAI increases maybe the cause of the earlier bulb scale initiation and maturitythat occurs as LAI increases. Onion, Allium cepa (L.), spacing, competition, leaf area index, red: far red, irrigation, nitrogen, shading, bulbing     

The effects of nitrogen, phosphorus, potassium and magnesium on the growth of tulips during the second season of treatment and on the chemical composition of the bulbs

In factorial nutrition treatments, for a second season, with three rates of nitrogen, phosphorus and potassium, and some additional treatments with magnesium, on two bulb sizes of Golden Harvest and Elmus tulip, the effect of nitrogen was again found to be dominant. Nitrogen deficiency decreased bulb yields, leaf area, stem length (with one exception) and flower size; it also retarded flowering: the majority of small nitrogen-deficient bulbs produced only single leaves. Deficiencies of phosphorus, potassium and magnesium had more marked effects than in the first season of treatment and generally reduced bulb yields and leaf area; in some instances stem length and flower size were also reduced. High phosphorus advanced the flowering of Elmus bulbs. The relationships between nutrition and mineral composition of the bulbs showed consistent trends determined by rates and duration of treatments, planting size and variety.     

The Initiation and Growth of Narcissus Bulbs

Plants of two Narcissus cultivars were dissected periodicallyover a year to study initiation, growth, and dry-weight changesof flowers and daughter bulb units in relation to the positionof the daughter bulbs in the branching system. A Narcissus bulbis a branching system comprising terminal and lateral bulb units;the former bear both terminal and lateral bulb units, but lateralscontain only terminal ones. This basic pattern may be modifiedby the failure of lateral bulb units or the development of supernumeraryones. Differences in bulb unit size, in scale and leaf number,and in flowering, related to position in the branching system,are probably due to the initiation of lateral bulb units somemonths after terminal ones. This affects the growth and behaviourof the laterals and daughter bulb units borne by these lateralsin the next generation. Bulb units live about four years; after the loss of their leafblades and flowers, the scales and leaf bases act as storageorgans whose weight increases or decreases according to thecarbohydrate status of the plant. Growth of bulb units showsan externally controlled alternation of rapid and slow growth.This is likely to be an effect of day length on bulbing.     

Environmental rearing conditions produce forebrain differences in wild Chinook salmon Oncorhynchus tshawytscha

Recent studies suggest that hatchery-reared fish can have smaller brain-to-body size ratios than wild fish. It is unclear, however, whether these differences are due to artificial selection or instead reflect differences in rearing environment during development. Here we explore how rearing conditions influence the development of two forebrain structures, the olfactory bulb and the telencephalon, in juvenile Chinook salmon (Oncorhynchus tshawytscha) spawned from wild-caught adults. First, we compared the sizes of the olfactory bulb and telencephalon between salmon reared in a wild stream vs. a conventional hatchery. We next compared the sizes of forebrain structures between fish reared in an enriched NATURES hatchery and fish reared in a conventional hatchery. All fish were size-matched and from the same genetic cohort. We found that olfactory bulb and telencephalon volumes relative to body size were significantly larger in wild fish compared to hatchery-reared fish. However, we found no differences between fish reared in enriched and conventional hatchery treatments. Our results suggest that significant differences in the volume of the olfactory bulb and telencephalon between hatchery and wild-reared fish can occur within a single generation.     

A new species of Pomphorhynchus (Acanthocephala: Palaeacanthocephala) in freshwater fishes from central Chile

This study describes a new species of Pomphorhynchus collected from Percilia gillissi Girard, 1855 from the Za?artu canal, between the sister basins of the Itata and Laja rivers, in central Chile. Pomphorhynchus moyanoi n. sp. is characterized by an asymmetrical, well-differentiated subspherical bulb and 12-14 longitudinal rows of 13-14 hooks; the third and the fourth hook in each row are stout. Among South American species, P. moyanoi n. sp. shows some similarities to the Chilean species P. yamagutii Schmidt & Hugghins, 1973, but it differs in having a longer neck, larger bulb, and different proboscis armature arrangement. Pomphorhynchus moyanoi n. sp. differs from P. patagonicus Ortubay, Ubeda, Semenas & Kennedy 1991, in the bulb shape (protuberances), number of rows, fourth hook size and basal hook size. Pomphorhynchus moyanoi n. sp. also differs from P. sphaericus in the arrangement of hooks (number of rows and hooks per row), length and width of the proboscis, neck width, and symmetry of the bulb.     

Relationships between Bulb Size, Apex Size and Flowering in Bulbous Iris cv. Ideal

Large, retarded bulbs of the Iris cv. Ideal flower readily after exposure to appropriate preplanting conditions, whereas smaller bulbs flower with decreased frequency. Flower initiation occurs when apices from large, retarded bulbs are cultured on either Murashige-Skoog medium supplemented with gibberellic acid, or on the same medium without gibberellic acid on which scales from large bulbs have been incubated. Since floral initiation seldom occurs in explants from small bulbs, it is likely that reduced flowering of small bulbs relates in part to characteristics of the apical meristem. Apical dome diameter is one characteristic of retarded (and freshly dug) bulbs that is positively correlated with bulb size. However, whereas prolonged storage at retarding temperature increases the frequency of flowering of smaller bulbs, there is not a concomitant increase in apical dome diameter. Moreover, the ratio of apical dome diameter to bulb size in freshly dug bulbs does not increase measurably with later digging date indicating that apical dome size is not correlated with bulb maturity.     

Study on the Annual Periodicity of Growth and Development of Friellaria Palldiclora Schrenk

According to the observations under the climate at 1700 meters above sea level of mountainous district, the annual periodity of growth and development of fritillary (Fritillaria pallidifora Schrenk.) is briefly described as folldowing: The young shoot sprouts out of the bulb and emerges from the soil in April every year, and forms flowers and fruits in succession. During this period the nutrients of underground bulbs exhaust themselves and a new buld is thereby regenerated. In the middle of June, the aerial part dried up. The regeneration bud in the underground bulb differentiats itself under the condition of 8–22 ℃ in surmruer and an axillary bud is simultaneously initiated. The bulb thus formed dormants in the winter. The growing period of fritillary is only 80–90 days above the ground and 270–280 days beneath the ground. Hence, the whole developmental process of a regeneration bud of fritillary has to pass through three successive growing seasons under the normal conditions in which the growth confined to the inside of bulb lengthens to 600 days approximately. With comparison of the other bulbous plants the characteristics of the development of fritillary may be defined as follows: 1. The regeneration bulb can be formed under the condition of short-day light on even under complete darkness. In contrast with fritillary, the formation of new bulb of onion and other bulbous plants occurs under the longdag light. 2. It is certainly known that a critical size of rhizome or bulb is required for flower formation of Iris and tulip. A similar phenomena has been observed for fritillary in the present experiment. The critical size of bulb for flower initiation of fritillary is taken by us as 1.8–2.7 girfresh weight and 1.2–2.2 cm in diameter. This has nothing to do with the age of the bulb. 3. Different optimum tempertures are neccessary for various developmental stages of fritillary respeetivtly. The normal development periodicity of fritillary may be modified by the onset of dormancy under the condition of low temperatures. Using this method, a secondary shoot will grow up in one growing season. This is in confirmation of the report on the experiment of an other fritillary.     

The effect of bulb size on the storage-life of onions

In 2 years, 1972 and 1973, onion bulbs were harvested on various dates, graded into a range of sizes and stored at ambient temperatures. Periodic assessments showed that the number of bulbs that both rotted and sprouted increased with increasing bulb size. Although rotting can be controlled with benomyl seed dressing the increased tendency of large bulbs to sprout could have commercial implications. The date of commencement of sprouting was not affected by bulb size, but the percentage increase of sprouting was faster in the larger bulbs. Delayed harvesting also led to increased sprouting in store.     

Contribution of explant carbohydrate reserves and sucrose in the medium to bulb growth of lily regenerated on scale segments in vitro

Bulb size is an important factor determining phase change in Lilium : phase change only occurs in bulblets over a certain threshold weight. After phase change has occurred, bulblets sprout with a stem with many leaves. Juvenile bulblets sprout with only a few leaves. The factors contributing to bulb size were studied during in vitro regeneration of bulblets on scale segments. The larger the explants, the larger the regenerated bulblets. Explant size influenced bulb growth during the complete culture period. Bulb growth was stimulated by a high sucrose concentration. The contribution of the medium and the explant reserves to bulb growth were studied in large and small explants using labelled sucrose. Sucrose was mainly taken up through the cut surfaces. In freshly cut explants, the rate of uptake was correlated with the size of the contact area, but at later stages, when regenerating organs were present, the difference in uptake rate of small and large explants almost disappeared. Small explants had a larger sink activity than large ones. Explants with regenerating organs took up more sucrose than freshly cut explants. Sucrose uptake and bulb growth were rather constant in the later phases and doubled when the sucrose concentration was doubled. Partitioning of label from the sucrose over the various organs, was also rather constant in time: approximately 25% was accumulated in the bulblets, 35–45% in the explant and 30–35% was converted to CO₂. About half of the label in the explant was recovered at the proximal side where regeneration takes place. Sucrose, once incorporated in the storage pools in the explant, either remained in the explant or was converted to CO₂. Redistribution to the growing bulblets hardly occurred. The percentage of bulb growth that could be attributed to uptake of medium components was constant over the regeneration period: 45–50% for large and 65–75% for small explants.     

Effect of Bulb Size on the Growth of Tulips

A study of the growth in the field of tulip plants from bulbsof four different sizes showed marked differences of leaf areaand shoot dry weight, those produced by larger bulbs being thegreater. Relative growth rates of the smaller plants were higherthan those of the large ones; this was due to different proportionsof total plant weight being non-growing mother bulb, as therelative growth rates of the shoots were not affected by bulbsize. The relative growth rates of daughter bulbs were alsounaffected by the mother bulb size, being very similar to previouslydetermined values in other sites and seasons. The final bulbyield was proportional to daughter bulb weight early in theseason. It is suggested that daughter bulb weight, shoot weight,and leaf area are directly related to the size of the motherbulb, and controlled by the factors determining mother bulbsize during its development.     

Some aspects of daughter bulb growth and development and apical dominance in bulbous Iris

Apical dominance appears to have minimal direct involvementin daughter bulb formation in the bulbous Iris cultivar Ideal.Daughter bulb number and growth relate to the size and reproductivestate of the mother bulb and are not markedly influenced bymeristem destruction. In contrast, destruction or removal ofthe apical meristem promotes lateral bud sprouting in intactbulbs, and lateral bud elongation in Iris meristem explants.These results show that, in contrast to certain other bulbousplants, apical dominance does not direcdy limit daughter bulbnumber in bulbous Iris, but does prevent lateral bud sprouting. (Received September 6, 1978; )     

Comparative study of the anatomy and laminar organization in the olfactory bulb of three orders of freshwater teleosts

The anatomy and lamination of the olfactory bulb in Cyprinus carpio, Tinca tinca, Barbus bocagei (Fam. Cyprinidae, Or. Cypriniformes); Salmo gairdneri (Fam. Salmonidae, Or. Salmoniformes); and Gambusia affinis (Fam. Poeciliidae, Or. Cyprinodontiformes), all of them freshwater teleosts, are studied. These species show significative differences on the location, size, morphology, and lamination of their olfactory bulbs. The presence of a new stratum in the olfactory bulb of Salmo gairdneri and a completely different laminar organization in the olfactory bulb of Gambusia affinis are described for the first time. The anatomical and histological peculiarities of this structure in the orders studied could be the basis for different experimental approaches.     

Carbon dioxide enrichment does not reduce leaf longevity or alter accumulation of carbon reserves in the woodland spring ephemeral Erythronium americanum

Background and Aims

Woodland spring ephemerals exhibit a relatively short epigeous growth period prior to canopy closure. However, it has been suggested that leaf senescence is induced by a reduction in the carbohydrate sink demand, rather than by changes in light availability. To ascertain whether a potentially higher net carbon (C) assimilation rate could shorten leaf lifespan due to an accelerated rate of storage, Erythronium americanum plants were grown under ambient (400 ppm) and elevated (1100 ppm) CO₂ concentrations.

Methods

During this growth-chamber experiment, plant biomass, bulb starch concentration and cell size, leaf phenology, gas exchange rates and nutrient concentrations were monitored.

Key Results

Plants grown at 1100 ppm CO₂ had greater net C assimilation rates than those grown at 400 ppm CO₂. However, plant size, final bulb mass, bulb filling rate and timing of leaf senescence did not differ.

Conclusions

Erythronium americanum fixed more C under elevated than under ambient CO₂ conditions, but produced plants of similar size. The similar bulb growth rates under both CO₂ concentrations suggest that the bulb filling rate is dependant on bulb cell elongation rate, rather than on C availability. Elevated CO₂ stimulated leaf and bulb respiratory rates; this might reduce feed-back inhibition of photosynthesis and avoid inducing premature leaf senescence.Key words: Source–sink relations, assimilation rates, growth rates, CO₂ enrichment, respiration, spring ephemeral, leaf senescence, bulbous plant, carbohydrate storage, Erythronium americanum     

The Initiation and Growth of Tulip Bulbs

Tulip mother bulbs contain daughter bulbs, and second-generationdaughter bulbs are initiated within these daughter bulbs, fromFebruary to July. Initiation takes place progressively, thefirst-initiated bulbs being in the axils of the outermost scales.The innermost second-generation daughter bulbs are finally initiatedat the same time as the flower within the daughter bulb. Thelatest-formed bulbs grow much more rapidly than the others,and soon become larger than the first-formed ones. Later inthe season, growth of daughter bulbs falls into three phases,corresponding roughly with autumn, winter, and spring; growthis rapid in autumn and spring, and slower in winter. The ratesof daughter bulb growth in the autumn are affected by the amountof suppression by the mother bulb apex, but later these differencesdisappear. The durations of the phases of growth also vary withthe position of the daughter bulb. The outer daughter bulbsgrow for a longer time during the autumn phase than the innerones, so that differences in size due to variation in growthrate are partly nullified. In early spring, all daughter bulbsresume rapid growth simultaneously. Final bulb weight is thenapproached asymptotically, with the innermost bulbs having thehighest weights.