The use of fecundity, lobe biometry and the RAPD-PCR technique in order to compare strains of Tetranychus sp.

In Belgium, recently two new red carmine forms of Tetranychus sp. have appeared on tomato crops in glasshouses and in maize crops. These forms maintain their red colour even during summer and on other host plants such as French bean. Our aim was to establish their status and to compare them with strains of Tetranychus urticae and Tetranychus cinnabarinus. A strain of Tetranychus kanzawai, a distant relative of the same genus, was used as a control. The five strains tested were characterized by their own demographic parameters, probably because of a longseparated evolution on different host plants. The white eye strain of T. urticae was differentiated from the four other strains by scanning electron microscopy studies of the dorsal integument folds. An investigation using the random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) showed T. cinnabarinus as a distinct group. However, the mixing of the individuals of the four other strains raises the question of the role of hybridization and host plant selection in the evolution of the Tetranychus complex. Exp Appl Acarol 22: 649–666 © 1998 Kluwer Academic Publishers     

Circadian Activity Rhythm of the House Fly Continues after Optic Tract Severance and Lobectomy

Under constant conditions, locomotor activity in about 50% of 63 adult Musca domestica continued to be rhythmic after bilateral severance of optic tracts or bilateral lobectomy. Apparently, the optic lobes of Musca do not contain the oscillator for rhythmic control of locomotor activity as has been proposed for other insects. In 20% of the individuals, several circadian components of activity rhythms were found after operation indicating a role of the optic lobes in the coupling of oscillators. The remaining 30% of the flies with severed optic tracts appeared to be arrhythmic. Most of these flies had vacuolized tissue in the central brain. However, disruption of rhythmicity did not correlate with a common pattern of degeneration. Therefore no conclusions can be drawn as to the localization of the circadian control of locomotor activity in the brain. Flies showing an arrhythmic activity pattern could still be synchronized by LD cycles. Activity did not occur solely during the light period as is the case in controls; but was phase delayed by about 6 hr towards the dark period. Since all flies with severed optic tracts could be synchronized by LD cycles, Musca domestica must possess extraocular photoreceptors.     

The functional morphology of mating in the Silurian eurypterid, Baltoeurypterus tetragonophthalmus (Fischer, 1839)

The functional morphology of the genital appendages, horn organs and modified prosomal limb III of the Silurian eurypterid, Baltoeurypterus tetragonophthalmus (Fischer, 1839) (Chelieerata: Eurypterida) is investigated. The longer type A genital appendage, interpreted as a female structure, is associated with a pair of horn organs, regarded as spermathecae. The shorter type B appendage, interpreted as male, is associated with scimitar lobes on prosomal limb III, regarded as clasping structures. A mechanism is proposed by which the type A appendage was lowered through flexure of the genital operculum acting along sutures in the cuticle. A model of mating is suggested, involving the male depositing an unstalked spermatophorc on the substrate and the female retrieving it for storage in the spermathecae. This model is more arachnid-like than mating in Limutus (an extant aquatic chclicerate), and suggests that sperm transfer using spcrmatophores and storage of sperm in spermathecae, allowed the timing of egg production in curyptcrids to be controlled.     

Effect of salt loading and salt deprivation on the vasopressin and oxytocin content of the median eminence and the neural lobe in adrenalectomized rats

Summary In adrenalectomized rats the influence of salt loading or salt deprivation on the vasopressin and oxytocin content of the median eminence (ME) and the neural lobe (NL) was studied by means of various methods: (1) morphometric and microphotometric analysis of aldehyde fuchsin-stained sections of ME and NL; (2) immunohistochemical demonstration of neurophysin, oxytocin, and vasopressin in the ME and in the NL; (3) radioimmunological measurement of oxytocin and vasopressin in the ME and in the NL. Adrenalectomy in salt-substituted rats raised the vasopressin content of the outer layer of the ME (OLME) but had no influence on the amount of vasopressin in the inner layer of the ME and in the NL. Osmotic stimulation of adrenalectomized rats by hypertonic saline markedly diminished vasopressin and oxytocin in the inner layer of the ME and in the NL but did not, or only slightly reduced vasopressin in the OLME. Withdrawal of salt supplementation in adrenalectomized rats resulted in a decrease of plasma sodium and plasma volume. It did not change the vasopressin or oxytocin content of the inner layer of the ME and of the NL, but it was correlated with a decrease of vasopressin in the OLME. The present findings may suggest that vasopressin in the OLME is involved in salt and/or volume regulation by influencing the hypophysial-adrenal axis.The study was supported by the Deutsche Forschungsgemeinschaft (Bo 392/6-5¹ and SFB 90, Cardiovasculäres System, A5²). The morphometric measurements with the TAS plus were carried out at the Max-Planck-Institut für Psychiatrie, Munich, FRG. We are particularly indebted to Prof. G. W. Kreutzberg and Prof. P. Schubert for their help     

Study on some genetic traits of Tibetans at Chandragiri, District Ganjam, Orissa

The incidence of ABH secretion, dry cerumen, ear-lobe attachment, hand clasping, arm-folding, and digital hair, occipital hair whorl and relative length of first and second toes is reported for Tibetan refugees. In those traits for which comparative data are available, they resemble Mongoloid rather than Caucasoid populations.     

Serotonin-immunoreactive neurons in the antennal lobes and suboesophageal ganglion of the honeybee

Summary We have used immunohistochemical methods to investigate the morphology of identified, presumptive serotonergic neurons in the antennal lobes and suboesophageal ganglion of the worker honeybee. A large interneuron (deutocerebral giant, DCG) is described that interconnects the deutocerebral antennal and dorsal lobes with the suboesophageal ganglion and descends into the ventral nerve chord. This neuron is accompanied by a second serotonin-immunoreactive interneuron with projections into the protocerebrum. Two pairs of bilateral immunoreactive serial homologues were identified in each of the three suboesophageal neuromeres and were also found in the thoracic ganglia. With the exception of the frontal commissure, no immunoreactive processes could be found in the peripheral nerves of the brain and the suboesophageal ganglion. The morphological studies on the serial homologues were extended by intracellular injections of Lucifer Yellow combined with immunofluorescence.     

IQ67 DOMAIN protein 21 is critical for indentation formation in pavement cell morphogenesis

In plants, cortical microtubules anchor to the plasma membrane in arrays and play important roles in cell shape. However, the molecular mechanism of microtubule binding proteins, which connect the plasma membrane and cortical microtubules in cell morphology remains largely unknown. Here, we report that a plasma membrane and microtubule duallocalized IQ67 domain protein, IQD21, is critical for cotyledon pavement cell(PC) morphogenesis in Arabidopsis. iqd21 mutation caused increased indentation wi...